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Hi Eugene. I am a big fan of your channel. However, in this video I saw a problem. At 02:00 you said the ship speed is same as light speed but the light ball is going faster than the ship in the animation which is contradictory with what you said. According to Shara’s point of view the light ball should not be moving faster than the ship in the animation. Please correct it or at least clarify if I am wrong. Thanks.
@@SazzadHissain It is not possible for an object with mass to travel at exactly the speed of light, but it is possible to get arbitrarily close to the speed of light. This is what I meant and this is why I show the light going slightly faster than the spaceship. Thanks.
@Eugene thanks for the clarification. It would be no confusing to audience if there would have been terms used like “almost same” instead of “equal”. Anyway, not a big deal. In your animations I found you extremely cautious about being scientifically consistent. I really appreciate your work. I would like to get videos about “shape of the universe” in future. ❤❤❤
In case, you have not already seen them, I uploaded several other videos within the past several days. As always, for each video that you like, you can help more people find it in their TH-cam search engine by clicking the like button, and writing a comment. Thanks.
Eugene Khutoryansky Hi Eugene. These videos are great! The oft repeating themes/points really help integrate these non-intuitive consequences of relativity. I wonder if you'll be able to explain causality in regards of how traveling faster than light can result in your past contacting you making this scenario a impossibility with our Einsteinium knowledge of the universe. Thank you!
The Sandre Guy Yes, the narration is done by a friend of mine who is a professional voice actor. She also created the song for the "Journey of the Fireflies" video on my channel.
What if Sarah starts walking away from Adam, and towards a real male who actually has the time and patience to care for her needs? Would Adam still be a douche and stay on that ship, playing with that STUPID ball, while this other dude steals his woman?
He wouldn’t know because time has essentially stopped and Sarah aged, married someone else, and died all in the time Adam blinked. He’s come back to Earth eventually and see Sarah is dead and it’d be too late to fix himself
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So...Adam's ship reaches the speed of light...How is it going to slow down? Adam is basically frozen in time, and so is the autopilot. He's gotta stay just below light speed for any of the ship's functions to actually work -- and work slowly, so RIP collision avoidance. Then, he get's where he's going, and realises that billions of years have passed back on earth, and he will never know how Game of Thrones ended. Still...it's better than what happened when he took the train. And a LOT better than what you go through at the airport.
@@lucasqwert1 Yeah, so actually who cares what Sarah sees, Adam is going to walk at normal speed from his pov so shouldn't he actually pass the speed of light? I know it isnt possible but this part wasnt explained
@@lucasqwert1 Adam sees that the whole universe is coming at him at light speed, so what happens for him when he steps forward, that would mean that everything is coming at him faster
just a thought: Cherenkov radiation. if electrons can travel faster than light in that medium; than all we have to do is find some particle than travels faster than light in a certain medium - like a warp bubble.
Andre Pascoa The speed of light (or rather, the speed of causality) is constant no matter the medium. Its just that the photons get absorbed and re-emitted constantly which effectively slows down light in a medium.
According to Albert Einstein’s Theory of Relativity, nothing can travel "through" space faster than the speed of light. But, the expansion of space itself causes the distance between faraway objects to increase faster than even light can travel.
Hello Eugene, I have a question not relevant to the point of this video, but rather just to the last seconds of it, where you show how bending space looks like due to gravity. I've been wanting to ask this question for a long time: in such animations we see space around i.e. a planet as a "soft ground" and planets as objects with mass that "dive into" that ground a little... but doesn't that occur in ALL directions? In space there's no up and down... what if I approach to the Sun/Earth or whatever from the bottom side in the animation? The reprezentation of space bent by black holes is also puzzling me.... what if I came to the black hole from the side of the infinitely warped space and not from the "top" of the black hole? I really have troubles imagining how such reprezentation of space bending looks like when acounting that space should bend in all directions? Maybe make a video about it :D :D P.S.: I really enjoyed yet another great video of yours :)
Antestor Ant The "indentation" shown in that space-time animation is not an indentation into one of our three know spacial dimensions. Rather, it is trying to show how space in a two dimensional Universe could warp in such a way that straight lines would look curved to the two dimensional beings that live there. The indentation, though, is not in the direction of one of the two spacial dimensions they are familiar with. In the same way, in the case of our three dimensional universe, the indentation would not be in the direction of one of our known three spacial dimensions.
Antestor Ant I believe the graphic is simply a representation of planets orbiting on the SAME 2D plane being distorted by gravity. We can understand it because we are visualizing it from the 3rd dimension. We would have to be able to visualize the 4th dimension to be able to comprehend a graphic without that misleading "quicksand" shape at the bottom. One does not simply approach a black hole "from the side." I too have troubles imagining. Eugene, please deliver us beyond our 3D comprehensive barrier.
Eugene Khutoryansky Thanks for the answer, I understand now (not meaning that I can visualize it though :D) Truly mind blowing, and unimaginable at least for me, what is the direction it warps and what dimension are we talking about here...It is really fascinating :)
Thank you for this video! I still have a question about it and i would be very happy if you could answer it. Isn`t it true that lightspeed is the same maximum speed in every (!) reference frame? Now what happens if Adam turns on a flashlight inside the ship? How would adam see it? I believe that adam does not experience any time slowing, right? Is the slowing of time which sarah sees only an optical effect for her and not for him?
In Adam’s perspective, he is stationary and it is the rest of the universe moving backwards, which will look contracted for him. Time will feel and flow normally for Adam. If he turned on a flashlight, he would see the photons from it traveling at the speed of light.
May I point out that if the ship is going at the speed of light, it doesn't matter if the time inside the ship is zero, Adam would be going (with the ship) at the speed of light. I suppose on thing to say is that this example is not feasible since the ship could not reach the speed of light according to the theory of relativity.
What always confused me, is the (possibly) only thing I remember from Physics classes. IF I remember, it is the Lorentz transformations that play a bigger part in calculations as you accelerate towards C. Externally observed mass heads toward infinity, externally observed time passage slows toward zero, and externally observed length in the direction of travel heads toward zero. My (long, drawn-out) point is: I always thought the equations said nothing that has mass can be OBSERVED to be going as fast, or faster than C. NOT that nothing can go as fast, or faster than C. Opinions? Please feel free to tell me my mistake(s)!
Another fundamental question is, how can a ship reach the speed of light when speed is a relative concept; it has to be measured against another object. It will have the speed according to this other object and yet have another speed if compared to another object. So ok, let's pick a star that relatively stable distance from the ship at start of acceleration. How can one measure practicaly his ship's speed according to a distant star? With the Doppler effect? I don't think that's possible. What happens to Doppler effect when your ship reaches relativistic speed. Then there's always measuring the amount of energy you add to your ship that gets converted to movement and add the amount needed to get to 'c'. But then the equations already tells you you need infinite energy. My conclusion; I smell something fishy. And I personaly believe that infinity is a math concept and is impossible in the physical univers. So, to me, a lot of theory and not enough exerimentations yet. As to your question, I read that Einstein never said a non zero mass object can have a FTL speed. It's just that a non zero mass object cannot accelerate to C.
Since I couldn't find anywhere else to post a suggestion I will add one here. I really like your videos and enjoy the wonderful learning I receive from them. I would really enjoy seeing a video about Nuclear energy, fission and fusion and some fundamental nuclear physics laws. Thanks for the videos! Keep it up!
At 2:05 if the ship is moving as fast as light, why is the photon outrunning the ship?? I get thet from sara’s perspective, adam isn’t moving due to time being stopped, and therefore light outruns adam. But it shouldn’t outrun the ship right?
But what about length contraction, when i studied this my teacher used Lorentz contraction to explane this phenomenon. Does the slowing down of time work with Lorentz or are they just happening on the same time?
Stefnir Húni Kristjánsson Lorentz contraction and the phenomena shown in this video up above always occur together. Although I didn't mention it in this video, I discussed Lorentz contraction in my main video on Relativity.
Eugene Khutoryansky Thank you for the answer and the quick reply :). btw love your videos its nice to see physics in such a visual manor instead of text and equations.
innerlocus Yes, no matter how far the photon traveled through empty space, from the photon's perspective, it traveled a distance of zero meters in zero seconds.
Eugene Khutoryansky But you can't say that. There simply aren't any reference frames in which a photon could be said to be at rest in. Timelike reference frames do not exist.
ashish nigam I just replied to your comment on the Twin Paradox video. Yes, there is no way to prove who is moving, and that is one of the fundamental principles in the Theory of Relativity. Each observer is equally correct in believing that they are standing still, and that it is the rest of the Universe that is moving around them. We can't detect absolute motion. We can only detect the motion of one object relative to another object.
Since I wrote on your quantum theory video, that I love your simulated cat, youtube started perpetually showing me cat food advertising. This is so spooky :D:D:D
Well sr was not violated for Sarah or Adam, but it was violated for us at 2:01 when the photon passed a space ship moving at speed of light hahaha! Great video I love your content
Actually, anything with mass (such as a spaceship) can never reach the speed of light, but it can arbitrarily close to the speed of light, and this is what I meant to say. Thanks.
@@EugeneKhutoryansky I know it does sound weird to me as well but the example stated "if the ship travels at the speed of light" (if you go click at 2:01 you will see it actually written and spoken) haha it's a funny mistake indeed, but ofc I'm by no means implying that you did not know this! Just thought it was a little funny moment lol
@@charlesbaoumar In this case actually Adam was supposed to move at the speed (tending to the speed) of light, and the spaceship - slightly slower than Adam's!
@@rdengin you're right! It's because she said "equal" even though it should be "approaching". My apologies for the misunderstanding Mrs Eugene my understanding was still premature but grew thanks to you formidable work! The best physics content on the internet by far!!!!!!!!!!!!!
Imagine you have 2 ships in 2 points of space. In some of your videos you showed how the universe is expanding and infinite. Thus one can know for sure that at some distance those 2 ships are 'moving' apart from each other greater than the speed of light. If you were on 1 ship and you could 'see' the other, would the relativistic effects still apply? Time and length would have negative values? Big fan of your work.
DisjoinedTech94 What I said in the other videos is that it is possible that the Universe is infinite. We don't know for sure whether it is or isn't. As for the expansion of the Universe, what is happening is that it is space itself that is expanding. One analogy is dots painted on a balloon that is being inflated. The dots are not moving on the surface of the balloon, but the distance between them is increasing. As for the question of what we would see if we looked at a galaxy who's distance from us is increasing faster than the speed of light, we would never see it, due to the fact that the light from it would never reach us.
At 2:07 you make the assumption that the ship is going exactly the speed of light, and yet the visualization you provide shows light actually still going faster than the ship. Not sure if that is a mistake, or an accurate depiction, but it seemed contradictory
To understand the last sentence means that travelling at 99,9 % of the "speed of light", you will see light moving at 299 792 km/h, therefore you will interpert your position as being stationnery. Unsychronised clocks with the earth would be the only way to know you're moving at that great speed. Am I missing out something ?
"The speed of light is 299,792,458 meters per second, but if you divide a second into 300,000,000 parts, time seems to pass between each interval faster than light can catch up."
If the speed of the spaceship reaches the speed of light in vacuum then from Sarah's perspective the length of the spaceship will be zero according to the length contraction formula right? Then how is Sarah supposed to see Adam?
So you are saying that when object is moving close to speed of light, time reduce to almost frozen in that object at the eye of observer. Then how can observer seeing that object moving so fast from point A to point B? And if we can see the "clock" on the photon itself, which is moving at speed of light, will we see that it freezes time on itself? So how long do we see it take for the flying object to take to travel A to B?
This thing drive me crazy. how can two events different at the different places.The light coming from the spaceship which make sarah to view adam's activities ,tell her exactly what is happening in the spaceship at same rate. what is going on there? ?
Hello, I have a doubt. What if we look at it another way. Sub atomic particles in particle accelerators travel at more than 99.99% the speed of light. what if we add that to the speed at which earth orbits the sun? Great video again, thanks.
Nev Bruh From Adam's perspective it's only going 10 meters per second. Remember, from his perspective he is standing still and it's the universe that is moving. From Sarah's perspective the ball is barely moving since she see's Adam's time to be nearly frozen.
Nev Bruh That's exactly what is explained in this video. From Adam's point of view (or anything inside the ship) his spaceship is not moving, so the rolling ball would be rolling at a normal speed from anyone's perspective inside the ship. Anyone else outside the ship would see it rolling extremely slow.
Amer Amodi It's relative. The Sun is moving in relation to Earth from the perspective of those on Earth. From the perspective of the Sun, the particles and those on Earth, time is slowed down so that it the speed of the particles appear less than the 99.99% that we would see on Earth.
Nev Bruh It would be somewhere between the speed of the spaceship and the speed of light. Much closer to the speed of the spaceship. Look up relative velocity for the equation. You will find that even everyday objects are moving ever so very slightly slower from someone else's perspective than from yours.
Guys I have a question. Suppose Adam and Sarah are both sitting in spaceships, and they both start to move very close to the speed of light, in opposite directions. Now to us, the third viewer, both of them individually are moving close to the speed of light (Let's call this speed c`). But let's say there is nothing else in the universe other than sarah and adam and their spaceships. Now, Adam is right to believe that his spaceship is standing still, but when he sees Sarah's spaceship, he sees her spaceship go 2c`, which is much higher than the speed of light, hence, violating Einstien's theory of relativity. Any thoughts?
+saksham chauhan That's an interesting question. I'm figuring that in this scenario, for both, Adam and Sarah, the length of the universe would contract to nearly zero - and since speed is measured as travelled distance in time, they would actually measure a speed close to zero. In the extreme scenario, if you replace them by light particles, from the perspective of the light particles, they would stay at the same place and wouldn't be moving at all (since the whole universe would be of size zero and the definition of space actually ceases to exist) And now my mind is twisted - I should probably go to bed ;-)
+saksham chauhan But its the same for sarah. If there is nothing else but her, adam and their spaceships both. They are both moving at speed c` from one another not 2c` From a third observer they see both ships travel at the same speed (almost 0). So Adam's ship speed = c` = Sarah's ship speed. From Adams point of view, his ship has been standing still for this whole duration and therefore sarahs ship hasnt moved at double speeds. she has been moving at exactly c` like she always have.
+saksham chauhan it makes me think that nothing with mass can go 1/2 of c wrt anything else with mass in the vicinity for that reason. meanwhile the distant galaxies are alleged to go faster than light from our perspective though we can't actually see them so they practically aren't breaking the rule because no one really can catch them. "what you don't know can't hurt you." "you'll have to catch me first."
ThomasHaberkorn I was wondering if anyone would comment on that. Yes, if Adam's spaceship was truly moving at the speed of light relative to Sarah, then from Sarah's perspective, the "light ball" would be standing still relative to the spaceship. However, it is not actually possible to go at the speed of light. It is only possible to approach arbitrarily close to the speed of light. Therefore, Sarah will always see the light going at least slightly faster than Adam's spaceship.
interesting, so you cant go faster because the faster you go the slower the time passes for you hence you'd be seeing the ball go faster than it "actually" is because for you X seconds would have passed but from the outside it would have been like X.1/10000 of a second? That means that there could be different parts of the universe "going" at different speeds of time relative to each other no? just one question. what if we stand still and send one object at the speed of light to the right and another also at that speed to the left? we would see each of them going slow and at 0.9999C but what would they see when they see each other? would it be like when you are on a train and another passes by in the opposite direction looking as if going twice as fast? (2C / its time passing twice as fast as the one standing still's)
Laharl Krichevskoy Yes, time in different part of the Universe can be moving at different speeds. In reply to your other question, if you throw a ball at almost the speed of light towards a space ship that is headed toward you at almost the speed of light, the person in the space ship will still see the ball as moving slower than the speed of light. This is due to the fact that from his perspective, he is the one who is standing still, and it is you who are moving towards him at almost the speed of light. Therefore, he will think that it is time for you which is moving slowly, and that you are therefore moving your arms very slowly when you throw the ball towards him, similarly to how Adam was seen by Sarah as throwing the ball very slowly.
I have a question when spaceships goes at exact speed of light Sarah will see Adam is not moving but according to Adam perspective he can't move his leg . he stops thinking as he is travelling with speed of light does this is true
I understand that when Adam looks outside that time is slowed and the universe looks contracted. Just as he begins walking at 1kph forward (relative to the ship) while the ship moves at 1kph less than light speed (relative to the outside), does he then see the universe contract from non-zero to zero length? And if he walks at 2kph, what does he see ouside then? Does the universe stretch in the opposite direction? Do outside clocks appear to go in reverse?
Shahin Goddousi Well, he walking 1 kilometer per hour faster relative to the ship will, in Sara's point of view, just add 2 × 10⁻⁹ meters per seconds to his velocity. Thing is, he'll _never_ reach light speed.
Simple Question: I've grasped the concept of Adam's clock moving slower from sarah's perspective but you say every action like throwing the ball or walking inside the spaceship by adam looks slower from sarah's perspective. why is it so actually?
Prakash Paudel Because from Sarah's perspective, it is time itself which is slowing down inside the spaceship. This means that from her perspective, every physical process, including all of Adam's actions, will slow down inside the spaceship as well.
What about Adam's perspective of the outside world? When he looks out the window as he walks inside the ship which is traveling near light speed, what does he see?
Shahin Goddousi From Adam's point of view, it is the rest of the Universe that is moving, and he therefore sees everyone else's clocks as going slower. Also, due to Lorentz contraction, he views the rest of the Universe as having contracted in length. This is covered in detail in my main video on Einstein's Theory of Relativity.
Why do we consider Sarah's perspective in the first place? If we do not consider Sarah's perspective, and assume Adam is walking in his spaceship, or even better fires a bullet from inside his spaceship which is travelling at a speed very close to that of speed of light, theoretically isn't the bullet travelling at a speed faster than the speed of light?
2:00 When spaceship moves at the speed of light Sarah won't see Adam always moving slower, than the speed of light. She will see him moving at the speed of light.
Objects with mass can never travel at exactly the speed of light, but they can get arbitrarily close to the speed of light, and that is what I was referring to.
Completely rhetorical question born out of curiosity.... If Adam is moving near the speed of light, how does Sarah have enough 'time' to determine whether or not Adam even 'exists' within the spaceship, let alone being able to perceive the presence of the spaceship...
So, if there's a spaceship going at the speed of light, and I switch on a bulb at the tail end of the spaceship, the light will never reach the front end?
It will. And it will pass it at the speed of light. Thats the thing with relativity, from your point of reference you will never be able to outrun light. But an outside observer like Sarah would see what you described.
But these "problems" with violating light speed are really a problem with the amount of time it takes the light from Adam's image to reach Sarah. Just because Adam "appears" to be walking slow or standing still does not mean that he actually IS!!! Right?? I know I don't understand like some of you, which is Exactly why I am trying to learn this!! when he throws the ball....the spaceship "appears" to be standing still but it actually is Not...right?? So wouldn't that mean he Could have beaten light speed but it just wouldn't Appear that way to observers due to the additional time it takes for the light of the image to reach Sara or whoever. I mean, if he walks forward he is not Actually gonna be walking super slow or standing still....it just Appears that way. Or No??
"it actually is Not" = in his reference frame, he's not perceiving himself as moving slowly, yes. That's "relativity" : each one its own reference. And also yes, there is the light, carrying the information about Adam walking, that will have some time to travel until Sarah's eye. Even with a classical mechanic thinking, the slowdown image is evident : during the couple seconds of adam throwing a ball, he'll have travelled roughly earth-moon distance. Sarah is not moving, at mid distance of earth and moon. She suddendly receive a lot of "blue adam" (due to blue shifting of light) coming. Then, being next to him she'll have a normal colored adam, but as static image (like a camera's picture). Then when he move away, she see a red adam (redshift). During the blue shift, adam will appear to quickly start to launch a ball, and in the redshift he'll appears to very slowly finish to launch the ball. The vulgarization of physics is tricky because the light does not move instantaneously from adam and sarah to the youtube screen ! I'm not sure, but maybe we can't perceive FTL even if it was happening through electromagnetism.
That's what Sarah would see and record as happening. The same way, if a star 50 light years from earth exploded, when we saw it we would record that the star exploded today. But on "Observer" on another "planet" 25 light years from the star, would have record that the star exploded 25 years ago.
The classic question most seem to ask: Is the light from a moving vehicle's headlight traveling faster than the speed of light relative to the road surface?
No, since you cant sum up the velocities like that when such velocities are relativistic (ie. light is involved). The driver of the car will observe that the light leaving his headlights is traveling at the speed of light. An outside observer outside the car will see the same thing. This is because the light is not a bullet. A bullet shot out of a moving car does move faster compared to a bullet shot while stationary. But light is also a wave. Imagine you have two boats on a lake. One is going fast, and one is stationary. Both of them drop a stone in the water. The wave caused by the stone propagates at the same speed, no matter which boat the stone was dropped from.
Assuming spaceship is moving close to light speed &1 second on spaceship is equal to 10 seconds on Sarah's clock. In 10 seconds spaceship would have travelled 10 light seconds. What speed will Adam calculate? 10 light seconds in 1 second, that would be 10 times speed of light?
What if adam shines a laser forwards instead of walking/throwing ball? Would the laser to adam move forwads at the speed of light? What would Sarah see?
Why Adams motion alone is dilated, even the spaceship is also moving at a speed nearer to c, why doesn't the movement of the spaceship appears to be dilated
I read some pages on a book and some other references regarding time travel, it says that time travel is possible if we can build a time machine that can travel faster than speed of light so my question here is: Is it true that if you travel faster than speed of light you will be travel back in time? my point here is time travel to the past
+Jet Cannon u need to understand lorentz transformation equation for that. its not that easy or intuitive thing unless you are really passionate about math and physics
Like varun swamy said, you have to understand the Lorentz transformation. But the equation isn't that tough to understand. For any moving object, you multiply its time, its length, and its mass by 1/√(1-v^2/c^2), where v is your velocity and c is the speed of light. As you can see, once your velocity equals c, then you end up dividing by zero, so everything pretty much breaks down there. And if your velocity is *greater* than c, then you end up with an imaginary number in the denominator, which isn't much better. And even if you ignore all that and just say "v greater than c equals negative time! So that must mean traveling into the past!" it still doesn't make much sense. That's also the factor by which your length contracts, so do you start to stretch out when you go faster than c? Or do you just gain negative length? What does that mean? And negative mass too? Not a very promising time machine.
what if you had two quantum entangled particles one on the spaceship and one on the earth and he fires a particle forward effecting the spin of the entangled particle which instantly effecting the other particle so in his time frame he send a particle at the speed of light forward and Sarah recorded the time when the quantum spin state changed and then could add both his speed plus the speed of light together doubling it does this work?
What about two ships flying towards each other at the near speed of light? Doesn't that exceed the speed of light when they cross or what happens exactly?
The crazy thing is, according to the theory of relativity, even if Adam is moving at a speed close to that of light (mind you, not equal) and Sarah is at rest, they will both find the speed of light to be the same, is: 2.998792458 * 10^8 m/s.
what if two spaceships would fly at each other at the exact opposite flight directions and each spaceship is moving at the speed of light doesn't it mean that the relative velocity of those ships is 2*C?
If we want to go "faster" than light, we stay still and expand and contract the SPACE around the ship because space can do what ever it wants. That is how the warp engines in Star Trek work. Expand space behind, contract space in front. And that's how to get to Alpha Centauri, 4.37 light years away, in a matter of weeks.
+Cameron Hawkins Using the warp drive also wouldn't lead to any time dilation so you could return to Earth without everyone you know aging dramatically.
Adam's clock is slowing down because the photon is having a longer distance to travel to reach the detector. Firing photons from both directions towards the middle and comparing the differences in frequencies will fix the problem.
@@EugeneKhutoryansky its the same phenomenon. You are still making the same mistake. The photon from the center ship will reach the trailing ship first as that ship is moving to meet it.
Time slows the closer you approach the speed of light according to mass. (the more mass the slower) Light has no mass (or almost), which is why the higgs boson particle can exeed the speed of light. (it has no mass)
+Apoorva Gupta watch lecture series by prof. shiva prasad from iit bombay on special theory of relativity. trust me, if u give some time to it, u will def understand it from this lecture series. all confusing things are explained quite intuitively and comprehensively
Great vid as always! :) A glass plate's thickness dictates the amount of reflected light. Some light scatters from the upper surface, some from the lower surface. According to QED, the upper surface reflection is affected by the distance to the lower surface. Since the upper surface appears to instantaneously know the distance to the lower surface, here is my attempt: A veeery thick glass plate with a variable thickness mechanism is placed between two planets. Light is shone on the upper surface and the amount of reflection is detected there. Could another person with the variable thickness control, on the other side of the glass plate, send instant morse signals in reflectivity?
If the spaceship is travelling at the speed of light, Adam will not move for Sarah, so he can't go faster than light. Ok, but the spaceship is already flying at the speed of light. Isn't it violating the relativity? it was just a fictional situation, because It's not possible to travel at the speed of light, right?
Rodrigo Appendino Well, problem is, he can't. It's simply nonsensical to say that something "travels at the speed of light," unless it's a massless particle.
time = motion. no motion = you stopped the time. you replay the motion in reverse manner = you reversed time. and the same for fast forwarding time. living organisms are hard to predict because their motion depends on brain decisions and not solely by the law of physics to get to a certain point.
can someone answer me please :one of the rules : that the speed of light is equale for all observors... but in the video here adam is at very fast speed and he sees the light as its moving sloweky not on the speed of light !! so for adams point of view the light is moving with a little speed which disagree the rule !can someone explaine please
Adam still sees the ball of light moving at the regular speed of light. This is because to measure this speed, he needs to use his clock inside the spaceship, and from the perspective of everyone outside this spaceship, his clock is running very slowly.
@@EugeneKhutoryansky i still didnt get it sorry...i think i need to understand the nature of light first before getting to understand this but anyway thanks for the quick respond i appreciate it
2:01 "If the ship's speed EQUALS the speed of light, Sarah will see time inside the spaceship stop completely, and she will see Adam's walking speed decrease to zero. Therefore, Sarah will always see Adam moving SLOWER than the speed of light." So the ship EQUALS the speed of time. Even if Adam keeps sitting or standing, Sarah will see Adam moving together with the spaceship AT the speed of light. Isn't it? If not please explain why. And BTW, you forgot to mention that if the ship's speed EQUALS the speed of light, it will have to stand against all the (extreme blue shifted -> gamma) radiation of the whole universe at once, since the distance shrinked to zero. IMO this is the challenge we will never ever be mastering, even if we are able to reach 99,9% of the speed of light.
The speed of the spaceship can never actually reach the speed of light, due to the fact that the spaceship has mass. But the spaceship can approach arbitrarily close to the speed of light, and that is really the scenario I was referring to.
Sarah will see the laser move at the speed of light, the same speed as that ball of light outside the spaceship. Whenever different observers measure the speed of light, they always get the same answer even if one is moving relative to the other.
There's a small inconsistency at 2:07, I think. If the spaceship is moving at the speed of light (assuming that's possible), then the photon should not be moving forward in the animation (ie. moving faster than the spaceship).
The spaceship is not moving at the speed of light, because objects with mass can never reach the speed of light. But, they can get arbitrarily close to the speed of light, and that is what I was trying to show. Thanks.
@@EugeneKhutoryansky You're right of course, and it's clear to me that that's the point you were making. It's just that the video explicitly explores the scenario where the spaceship travels at the speed of light (surely because it was necessary to show that you can't (theoretically) make a step forward at all at the speed of light to break it). Assuming that this was possible however, the photon should be moving at the same speed as the ship. Also, let me take this opportunity to say that I've been watching your amazing videos throughout the years and they really helped me better understand physics! I really appreciate your work, thank you so much! 😊
Speed of light depends on its medium. Space in a galaxy is denser than outside galaxy. Therefore speed of light in free space is greater than on earth.
Thanks for reply In your video u says that adam is in spaceship and he throughs the ball forward(or walk forward). In my queastin adam is in space ship but sara through tha ball backward(or walk backward). According the theory, sara feels that adam's time is moving slow so adam feels that sara's time is moving fast. And if sara through the ball backward(or walk bacward), Due to fast moving time, ball is going fast. So according to adam's view sara is moving backward nearly the speed of light and through the ball backward so ball is going faster than light.
ashish nigam No, Adam does not view Sarah's time as moving fast. Adam sees Sarah's time as moving slowly. Both Adam and Sarah view the other person's clock as moving slower than their own. If this were not the case, then it would be possible to tell who is moving, which would violate the founding principle of Einstein's Theory of Relativity.
Eugene Khutoryansky then according to photon perspective i m going with the speed of light and my clock's tick stop. And if sara and adam both feel that other person's time slower than thair own so both feel that they r older than other. Then who is in future relative to other. And if i wish go into future so if i will go with speed nearly to light then i will see that others person's clock slower than me so they will going in future not i. And according to others i m in future. Totly contradictid. Is there r any proof of ttheory of relativity???????
ashish nigam I cover that question in detail in my "Twin Paradox" video. You can find it in the links at the end of the video up above, or from my TH-cam home page. Thanks.
I have predıcted with my theory and my formula 6.3 tımes greater than the speed of light, which is measured as if apparently inside of M87 black hole. I SUGGEST HAVING A LOOK AT THE FIRST PART OF MY THEORY AND MY FIRST FORMULA WHICH DETERMINES A LINEAR VELOCITY OF...6.3 TIMES GREATER THAN THE SPEED OF LIGHT, ETC. AND I TOLD WHERE OUR MEASURED CONSTANTS ARE ROOTED IN. We need to change the concept of matter that makes us imprisoned by all kinds of impressions and especially by accepting the vacuum illusion which it has been sitting comfortably in it
Nothing can not go faster then the speed of light. But the thing is the space the mass is passing though is a different thing at the moment space is expanding faster then the speed of light So the only way to move though space faster then the speed of light is to shrink the space the mass is passing though
If sara through the ball in opposite direction of adam. Since sara's time faster than adam. And according to adam's perspectiive he is still and sara is moving nearly the speed of light and she throughs a ball and her time faster than adam then it looks like ball is going faster than light (according to adam's perspective). And according the logic of twin paradox sara's time never slower than adam's
And if u say from adam's perspective that sara's time go slower then adam's then it is again creat twin paradox. And sorry for my english Waiting for your answer
ashish nigam I am not sure if I understood your question properly. From Adam's perspective, he is standing still. Therefore, no matter what direction he throws the ball, he will always think that the ball is moving much slower than the speed of light. If this doesn't answer the question you were trying to ask, please let me know.
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Hi Eugene. I am a big fan of your channel. However, in this video I saw a problem. At 02:00 you said the ship speed is same as light speed but the light ball is going faster than the ship in the animation which is contradictory with what you said. According to Shara’s point of view the light ball should not be moving faster than the ship in the animation. Please correct it or at least clarify if I am wrong. Thanks.
@@SazzadHissain It is not possible for an object with mass to travel at exactly the speed of light, but it is possible to get arbitrarily close to the speed of light. This is what I meant and this is why I show the light going slightly faster than the spaceship. Thanks.
@Eugene thanks for the clarification. It would be no confusing to audience if there would have been terms used like “almost same” instead of “equal”. Anyway, not a big deal. In your animations I found you extremely cautious about being scientifically consistent. I really appreciate your work. I would like to get videos about “shape of the universe” in future. ❤❤❤
@@SazzadHissain Thanks. I already have a video on the shape of the Universe at th-cam.com/video/IFdfrtzo4SY/w-d-xo.html
In case, you have not already seen them, I uploaded several other videos within the past several days. As always, for each video that you like, you can help more people find it in their TH-cam search engine by clicking the like button, and writing a comment. Thanks.
Eugene Khutoryansky Hi Eugene. These videos are great! The oft repeating themes/points really help integrate these non-intuitive consequences of relativity.
I wonder if you'll be able to explain causality in regards of how traveling faster than light can result in your past contacting you making this scenario a impossibility with our Einsteinium knowledge of the universe. Thank you!
LostLucidity I'll put that on my list of future videos to make. Thanks for the suggestion.
Eugene Khutoryansky Each as brilliant as the last
Eugene Khutoryansky Is it a friend of yours who does the voiceover?
The Sandre Guy Yes, the narration is done by a friend of mine who is a professional voice actor. She also created the song for the "Journey of the Fireflies" video on my channel.
Couldn't help but hear sarcasm in your voice when you said the word clever :)
What if Sarah starts walking away from Adam, and towards a real male who actually has the time and patience to care for her needs? Would Adam still be a douche and stay on that ship, playing with that STUPID ball, while this other dude steals his woman?
He wouldn’t know because time has essentially stopped and Sarah aged, married someone else, and died all in the time Adam blinked. He’s come back to Earth eventually and see Sarah is dead and it’d be too late to fix himself
Sarah is Adam's big sister. He would be okay with it.
but i still love the way she turns her head everytime she feels adam coming
At least she did not escape in a spaceship with the fantasies of moving faster than light after their mother died.
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Thanks.
I never thought about the theory of relativity this way! Outstanding clarification as always. 😁
Thanks.
So...Adam's ship reaches the speed of light...How is it going to slow down? Adam is basically frozen in time, and so is the autopilot. He's gotta stay just below light speed for any of the ship's functions to actually work -- and work slowly, so RIP collision avoidance. Then, he get's where he's going, and realises that billions of years have passed back on earth, and he will never know how Game of Thrones ended.
Still...it's better than what happened when he took the train. And a LOT better than what you go through at the airport.
From Adams point of view, time is not standing still but normal.
@@lucasqwert1 Yeah, so actually who cares what Sarah sees, Adam is going to walk at normal speed from his pov so shouldn't he actually pass the speed of light? I know it isnt possible but this part wasnt explained
@@lucasqwert1 Adam sees that the whole universe is coming at him at light speed, so what happens for him when he steps forward, that would mean that everything is coming at him faster
Excellent video, thanks for making them.
blake301987 Thanks. I am glad you like them.
just a thought: Cherenkov radiation. if electrons can travel faster than light in that medium; than all we have to do is find some particle than travels faster than light in a certain medium - like a warp bubble.
It'll still be slower than speed of light in vacuum so it'd be the same as going below the speed of light
Since the speed of light in vacuum is at its peak while in a medium it is slower
Andre Pascoa The speed of light (or rather, the speed of causality) is constant no matter the medium. Its just that the photons get absorbed and re-emitted constantly which effectively slows down light in a medium.
Arent there galaxies moving away from us as space expands faster then the speed of light? How can this be reconciled w special relativity?
According to Albert Einstein’s Theory of Relativity, nothing can travel "through" space faster than the speed of light. But, the expansion of space itself causes the distance between faraway objects to increase faster than even light can travel.
Hello Eugene,
I have a question not relevant to the point of this video, but rather just to the last seconds of it, where you show how bending space looks like due to gravity. I've been wanting to ask this question for a long time:
in such animations we see space around i.e. a planet as a "soft ground" and planets as objects with mass that "dive into" that ground a little... but doesn't that occur in ALL directions? In space there's no up and down... what if I approach to the Sun/Earth or whatever from the bottom side in the animation?
The reprezentation of space bent by black holes is also puzzling me.... what if I came to the black hole from the side of the infinitely warped space and not from the "top" of the black hole?
I really have troubles imagining how such reprezentation of space bending looks like when acounting that space should bend in all directions?
Maybe make a video about it :D :D
P.S.: I really enjoyed yet another great video of yours :)
Antestor Ant The "indentation" shown in that space-time animation is not an indentation into one of our three know spacial dimensions. Rather, it is trying to show how space in a two dimensional Universe could warp in such a way that straight lines would look curved to the two dimensional beings that live there. The indentation, though, is not in the direction of one of the two spacial dimensions they are familiar with. In the same way, in the case of our three dimensional universe, the indentation would not be in the direction of one of our known three spacial dimensions.
Antestor Ant I believe the graphic is simply a representation of planets orbiting on the SAME 2D plane being distorted by gravity. We can understand it because we are visualizing it from the 3rd dimension. We would have to be able to visualize the 4th dimension to be able to comprehend a graphic without that misleading "quicksand" shape at the bottom. One does not simply approach a black hole "from the side."
I too have troubles imagining. Eugene, please deliver us beyond our 3D comprehensive barrier.
Eugene Khutoryansky Thanks for the answer, I understand now (not meaning that I can visualize it though :D) Truly mind blowing, and unimaginable at least for me, what is the direction it warps and what dimension are we talking about here...It is really fascinating :)
Love your videos. Very well made and I prefer this over text on a page:
Sam Thanks. I am glad to hear that you like my videos.
Great video once again. You send a lot of amazing videos lately eugene cant wait for the next one!!
Great videos,very educational and simple,can you do a video about integrals and how do they work in physical equations?
Thanks for the compliment. I already have a video on integrals. That is the video titled "Calculus -- The foundation of modern science" Thanks.
Thank you for this video! I still have a question about it and i would be very happy if you could answer it. Isn`t it true that lightspeed is the same maximum speed in every (!) reference frame? Now what happens if Adam turns on a flashlight inside the ship? How would adam see it? I believe that adam does not experience any time slowing, right? Is the slowing of time which sarah sees only an optical effect for her and not for him?
In Adam’s perspective, he is stationary and it is the rest of the universe moving backwards, which will look contracted for him. Time will feel and flow normally for Adam. If he turned on a flashlight, he would see the photons from it traveling at the speed of light.
May I point out that if the ship is going at the speed of light, it doesn't matter if the time inside the ship is zero, Adam would be going (with the ship) at the speed of light. I suppose on thing to say is that this example is not feasible since the ship could not reach the speed of light according to the theory of relativity.
What always confused me, is the (possibly) only thing I remember from Physics classes. IF I remember, it is the Lorentz transformations that play a bigger part in calculations as you accelerate towards C. Externally observed mass heads toward infinity, externally observed time passage slows toward zero, and externally observed length in the direction of travel heads toward zero.
My (long, drawn-out) point is:
I always thought the equations said nothing that has mass can be OBSERVED to be going as fast, or faster than C. NOT that nothing can go as fast, or faster than C.
Opinions? Please feel free to tell me my mistake(s)!
Another fundamental question is, how can a ship reach the speed of light when speed is a relative concept; it has to be measured against another object. It will have the speed according to this other object and yet have another speed if compared to another object. So ok, let's pick a star that relatively stable distance from the ship at start of acceleration. How can one measure practicaly his ship's speed according to a distant star? With the Doppler effect? I don't think that's possible. What happens to Doppler effect when your ship reaches relativistic speed. Then there's always measuring the amount of energy you add to your ship that gets converted to movement and add the amount needed to get to 'c'. But then the equations already tells you you need infinite energy. My conclusion; I smell something fishy. And I personaly believe that infinity is a math concept and is impossible in the physical univers. So, to me, a lot of theory and not enough exerimentations yet.
As to your question, I read that Einstein never said a non zero mass object can have a FTL speed. It's just that a non zero mass object cannot accelerate to C.
Since I couldn't find anywhere else to post a suggestion I will add one here. I really like your videos and enjoy the wonderful learning I receive from them. I would really enjoy seeing a video about Nuclear energy, fission and fusion and some fundamental nuclear physics laws.
Thanks for the videos! Keep it up!
Jake White Yes, nuclear physics is on my list of topics that I plant to do videos on. Thanks.
At 2:05 if the ship is moving as fast as light, why is the photon outrunning the ship?? I get thet from sara’s perspective, adam isn’t moving due to time being stopped, and therefore light outruns adam. But it shouldn’t outrun the ship right?
Your videos are amazing! Keep up the good work!
But what about length contraction, when i studied this my teacher used Lorentz contraction to explane this phenomenon. Does the slowing down of time work with Lorentz or are they just happening on the same time?
Stefnir Húni Kristjánsson Lorentz contraction and the phenomena shown in this video up above always occur together. Although I didn't mention it in this video, I discussed Lorentz contraction in my main video on Relativity.
Eugene Khutoryansky Thank you for the answer and the quick reply :). btw love your videos its nice to see physics in such a visual manor instead of text and equations.
Since the photon moves at a speed where time stands still, does the photon experience no time, no space?
innerlocus Yes, no matter how far the photon traveled through empty space, from the photon's perspective, it traveled a distance of zero meters in zero seconds.
Eugene Khutoryansky But you can't say that. There simply aren't any reference frames in which a photon could be said to be at rest in. Timelike reference frames do not exist.
Eugene Khutoryansky Woah, that is rather interesting. Would you mind to explain more?
By the way, your videos are AWESOME, thank you a lot.
Markus What he means is that a photon is emitted and absorbed instantly, from its reference frame it doesnt even exist.
so adam didnt die when he threw the ball outside of his spaceship without spacesuit xD
Nice video
Please reply on twin paradox's video
I m very curious to know
ashish nigam I just replied to your comment on the Twin Paradox video. Yes, there is no way to prove who is moving, and that is one of the fundamental principles in the Theory of Relativity. Each observer is equally correct in believing that they are standing still, and that it is the rest of the Universe that is moving around them. We can't detect absolute motion. We can only detect the motion of one object relative to another object.
Since I wrote on your quantum theory video, that I love your simulated cat, youtube started perpetually showing me cat food advertising. This is so spooky :D:D:D
Well sr was not violated for Sarah or Adam, but it was violated for us at 2:01 when the photon passed a space ship moving at speed of light hahaha! Great video I love your content
Actually, anything with mass (such as a spaceship) can never reach the speed of light, but it can arbitrarily close to the speed of light, and this is what I meant to say. Thanks.
@@EugeneKhutoryansky I know it does sound weird to me as well but the example stated "if the ship travels at the speed of light" (if you go click at 2:01 you will see it actually written and spoken) haha it's a funny mistake indeed, but ofc I'm by no means implying that you did not know this! Just thought it was a little funny moment lol
@@charlesbaoumar In this case actually Adam was supposed to move at the speed (tending to the speed) of light, and the spaceship - slightly slower than Adam's!
@@rdengin you're right! It's because she said "equal" even though it should be "approaching". My apologies for the misunderstanding Mrs Eugene my understanding was still premature but grew thanks to you formidable work! The best physics content on the internet by far!!!!!!!!!!!!!
Imagine you have 2 ships in 2 points of space. In some of your videos you showed how the universe is expanding and infinite. Thus one can know for sure that at some distance those 2 ships are 'moving' apart from each other greater than the speed of light. If you were on 1 ship and you could 'see' the other, would the relativistic effects still apply? Time and length would have negative values? Big fan of your work.
DisjoinedTech94 What I said in the other videos is that it is possible that the Universe is infinite. We don't know for sure whether it is or isn't. As for the expansion of the Universe, what is happening is that it is space itself that is expanding. One analogy is dots painted on a balloon that is being inflated. The dots are not moving on the surface of the balloon, but the distance between them is increasing. As for the question of what we would see if we looked at a galaxy who's distance from us is increasing faster than the speed of light, we would never see it, due to the fact that the light from it would never reach us.
Awesome Eugene!! Thank you so much for another great, fun video to watch!
Diogo Canina Thanks. I am glad you liked it.
Eugene Khutoryansky Yes I do like all of them, however, the Electromagnetism video is by far my favorite yet. Good job!!
At 2:07 you make the assumption that the ship is going exactly the speed of light, and yet the visualization you provide shows light actually still going faster than the ship. Not sure if that is a mistake, or an accurate depiction, but it seemed contradictory
I was showing that an object with mass always has to be at least slightly slower than the speed of light.
Physics Videos by Eugene Khutoryansky Understood. Thanks for the response
To understand the last sentence means that travelling at 99,9 % of the "speed of light", you will see light moving at 299 792 km/h, therefore you will interpert your position as being stationnery. Unsychronised clocks with the earth would be the only way to know you're moving at that great speed. Am I missing out something ?
"The speed of light is 299,792,458 meters per second, but if you divide a second into 300,000,000 parts, time seems to pass between each interval faster than light can catch up."
If the speed of the spaceship reaches the speed of light in vacuum then from Sarah's perspective the length of the spaceship will be zero according to the length contraction formula right? Then how is Sarah supposed to see Adam?
2:30 I think the spaceship and Adam should go as fast as this photon?
So you are saying that when object is moving close to speed of light, time reduce to almost frozen in that object at the eye of observer. Then how can observer seeing that object moving so fast from point A to point B? And if we can see the "clock" on the photon itself, which is moving at speed of light, will we see that it freezes time on itself? So how long do we see it take for the flying object to take to travel A to B?
This thing drive me crazy. how can two events different at the different places.The light coming from the spaceship which make sarah to view adam's activities ,tell her exactly what is happening in the spaceship at same rate. what is going on there? ?
Hello,
I have a doubt. What if we look at it another way. Sub atomic particles in particle accelerators travel at more than 99.99% the speed of light. what if we add that to the speed at which earth orbits the sun? Great video again, thanks.
Nev Bruh From Adam's perspective it's only going 10 meters per second. Remember, from his perspective he is standing still and it's the universe that is moving. From Sarah's perspective the ball is barely moving since she see's Adam's time to be nearly frozen.
Nev Bruh That's exactly what is explained in this video. From Adam's point of view (or anything inside the ship) his spaceship is not moving, so the rolling ball would be rolling at a normal speed from anyone's perspective inside the ship.
Anyone else outside the ship would see it rolling extremely slow.
Amer Amodi It's relative. The Sun is moving in relation to Earth from the perspective of those on Earth. From the perspective of the Sun, the particles and those on Earth, time is slowed down so that it the speed of the particles appear less than the 99.99% that we would see on Earth.
Nev Bruh That is relative to where the light originated.
Nev Bruh It would be somewhere between the speed of the spaceship and the speed of light. Much closer to the speed of the spaceship. Look up relative velocity for the equation. You will find that even everyday objects are moving ever so very slightly slower from someone else's perspective than from yours.
Guys I have a question. Suppose Adam and Sarah are both sitting in spaceships, and they both start to move very close to the speed of light, in opposite directions. Now to us, the third viewer, both of them individually are moving close to the speed of light (Let's call this speed c`). But let's say there is nothing else in the universe other than sarah and adam and their spaceships. Now, Adam is right to believe that his spaceship is standing still, but when he sees Sarah's spaceship, he sees her spaceship go 2c`, which is much higher than the speed of light, hence, violating Einstien's theory of relativity. Any thoughts?
+saksham chauhan That's an interesting question. I'm figuring that in this scenario, for both, Adam and Sarah, the length of the universe would contract to nearly zero - and since speed is measured as travelled distance in time, they would actually measure a speed close to zero. In the extreme scenario, if you replace them by light particles, from the perspective of the light particles, they would stay at the same place and wouldn't be moving at all (since the whole universe would be of size zero and the definition of space actually ceases to exist) And now my mind is twisted - I should probably go to bed ;-)
haha nice views, and good night :)
+saksham chauhan But its the same for sarah. If there is nothing else but her, adam and their spaceships both. They are both moving at speed c` from one another not 2c`
From a third observer they see both ships travel at the same speed (almost 0). So Adam's ship speed = c` = Sarah's ship speed.
From Adams point of view, his ship has been standing still for this whole duration and therefore sarahs ship hasnt moved at double speeds. she has been moving at exactly c` like she always have.
+klaik30 that doesn't make any useful sense. i don't think you understood his hypothetical scenario.
+saksham chauhan it makes me think that nothing with mass can go 1/2 of c wrt anything else with mass in the vicinity for that reason. meanwhile the distant galaxies are alleged to go faster than light from our perspective though we can't actually see them so they practically aren't breaking the rule because no one really can catch them. "what you don't know can't hurt you." "you'll have to catch me first."
What happens when someone drives a motorcycle? Does time appear slower for the driver?
2:10 wait.. shoudn't the "light ball" stand still relative to the space ship (because the have equal speed measured from Sarah's prespective)?
ThomasHaberkorn I was wondering if anyone would comment on that. Yes, if Adam's spaceship was truly moving at the speed of light relative to Sarah, then from Sarah's perspective, the "light ball" would be standing still relative to the spaceship. However, it is not actually possible to go at the speed of light. It is only possible to approach arbitrarily close to the speed of light. Therefore, Sarah will always see the light going at least slightly faster than Adam's spaceship.
well.. that's what I wanted to say next :) Unless the ship has zero rest mass.. and Adam as well
interesting, so you cant go faster because the faster you go the slower the time passes for you hence you'd be seeing the ball go faster than it "actually" is because for you X seconds would have passed but from the outside it would have been like X.1/10000 of a second?
That means that there could be different parts of the universe "going" at different speeds of time relative to each other no?
just one question. what if we stand still and send one object at the speed of light to the right and another also at that speed to the left? we would see each of them going slow and at 0.9999C but what would they see when they see each other? would it be like when you are on a train and another passes by in the opposite direction looking as if going twice as fast? (2C / its time passing twice as fast as the one standing still's)
Laharl Krichevskoy Yes, time in different part of the Universe can be moving at different speeds. In reply to your other question, if you throw a ball at almost the speed of light towards a space ship that is headed toward you at almost the speed of light, the person in the space ship will still see the ball as moving slower than the speed of light. This is due to the fact that from his perspective, he is the one who is standing still, and it is you who are moving towards him at almost the speed of light. Therefore, he will think that it is time for you which is moving slowly, and that you are therefore moving your arms very slowly when you throw the ball towards him, similarly to how Adam was seen by Sarah as throwing the ball very slowly.
Laharl Krichevskoy There's no absolute time. Only relative. When talking about time dilation, we are simply talking about *ratios*.
adam will also be contracted and so will the spaceship, which makes moving forward slower
I have a question when spaceships goes at exact speed of light Sarah will see Adam is not moving but according to Adam perspective he can't move his leg . he stops thinking as he is travelling with speed of light does this is true
U forgot that the horizontal length is also contracted, meaning that one Adam's step is way less than his 'usual'
Someone could please give me the name of the background song?
Dante Villalobos It is from the free TH-cam audio library, and it is titled
"From_Russia_with_Love"
Thanks.
Eugene Khutoryansky Thank you very much, by the way I love your videos, they are so well explained. Keep up the good work:)
I understand that when Adam looks outside that time is slowed and the universe looks contracted. Just as he begins walking at 1kph forward (relative to the ship) while the ship moves at 1kph less than light speed (relative to the outside), does he then see the universe contract from non-zero to zero length? And if he walks at 2kph, what does he see ouside then? Does the universe stretch in the opposite direction? Do outside clocks appear to go in reverse?
Shahin Goddousi Well, he walking 1 kilometer per hour faster relative to the ship will, in Sara's point of view, just add 2 × 10⁻⁹ meters per seconds to his velocity. Thing is, he'll _never_ reach light speed.
What if you shine the light inside of the space ship?
Damn you Physics. We will break you one day. Mark my words.
Simple Question:
I've grasped the concept of Adam's clock moving slower from sarah's perspective but you say every action like throwing the ball or walking inside the spaceship by adam looks slower from sarah's perspective. why is it so actually?
Prakash Paudel Because from Sarah's perspective, it is time itself which is slowing down inside the spaceship. This means that from her perspective, every physical process, including all of Adam's actions, will slow down inside the spaceship as well.
excellent visualization. i have wanted to see this depicted. saves me from using chips of bark to try to imagine.
What about Adam's perspective of the outside world? When he looks out the window as he walks inside the ship which is traveling near light speed, what does he see?
Shahin Goddousi From Adam's point of view, it is the rest of the Universe that is moving, and he therefore sees everyone else's clocks as going slower. Also, due to Lorentz contraction, he views the rest of the Universe as having contracted in length. This is covered in detail in my main video on Einstein's Theory of Relativity.
So it's impossible to move at the speed of light but it is possible to move slightly slower than the speed of light right
yugioh guy in theory
Why do we consider Sarah's perspective in the first place? If we do not consider Sarah's perspective, and assume Adam is walking in his spaceship, or even better fires a bullet from inside his spaceship which is travelling at a speed very close to that of speed of light, theoretically isn't the bullet travelling at a speed faster than the speed of light?
2:00 When spaceship moves at the speed of light Sarah won't see Adam always moving slower, than the speed of light. She will see him moving at the speed of light.
Objects with mass can never travel at exactly the speed of light, but they can get arbitrarily close to the speed of light, and that is what I was referring to.
@@EugeneKhutoryansky I am aware of this fact, thanks! In general I really appreciate your efforts to explain complex things in a simple way! Thanks!
Completely rhetorical question born out of curiosity.... If Adam is moving near the speed of light, how does Sarah have enough 'time' to determine whether or not Adam even 'exists' within the spaceship, let alone being able to perceive the presence of the spaceship...
So, if there's a spaceship going at the speed of light, and I switch on a bulb at the tail end of the spaceship, the light will never reach the front end?
It will. And it will pass it at the speed of light. Thats the thing with relativity, from your point of reference you will never be able to outrun light. But an outside observer like Sarah would see what you described.
But these "problems" with violating light speed are really a problem with the amount of time it takes the light from Adam's image to reach Sarah. Just because Adam "appears" to be walking slow or standing still does not mean that he actually IS!!! Right?? I know I don't understand like some of you, which is Exactly why I am trying to learn this!! when he throws the ball....the spaceship "appears" to be standing still but it actually is Not...right?? So wouldn't that mean he Could have beaten light speed but it just wouldn't Appear that way to observers due to the additional time it takes for the light of the image to reach Sara or whoever. I mean, if he walks forward he is not Actually gonna be walking super slow or standing still....it just Appears that way. Or No??
"it actually is Not" = in his reference frame, he's not perceiving himself as moving slowly, yes. That's "relativity" : each one its own reference. And also yes, there is the light, carrying the information about Adam walking, that will have some time to travel until Sarah's eye.
Even with a classical mechanic thinking, the slowdown image is evident : during the couple seconds of adam throwing a ball, he'll have travelled roughly earth-moon distance. Sarah is not moving, at mid distance of earth and moon. She suddendly receive a lot of "blue adam" (due to blue shifting of light) coming. Then, being next to him she'll have a normal colored adam, but as static image (like a camera's picture). Then when he move away, she see a red adam (redshift).
During the blue shift, adam will appear to quickly start to launch a ball, and in the redshift he'll appears to very slowly finish to launch the ball.
The vulgarization of physics is tricky because the light does not move instantaneously from adam and sarah to the youtube screen ! I'm not sure, but maybe we can't perceive FTL even if it was happening through electromagnetism.
That's what Sarah would see and record as happening. The same way, if a star 50 light years from earth exploded, when we saw it we would record that the star exploded today. But on "Observer" on another "planet" 25 light years from the star, would have record that the star exploded 25 years ago.
The classic question most seem to ask:
Is the light from a moving vehicle's headlight traveling faster than the speed of light relative to the road surface?
No, since you cant sum up the velocities like that when such velocities are relativistic (ie. light is involved). The driver of the car will observe that the light leaving his headlights is traveling at the speed of light. An outside observer outside the car will see the same thing. This is because the light is not a bullet. A bullet shot out of a moving car does move faster compared to a bullet shot while stationary.
But light is also a wave. Imagine you have two boats on a lake. One is going fast, and one is stationary. Both of them drop a stone in the water. The wave caused by the stone propagates at the same speed, no matter which boat the stone was dropped from.
Assuming spaceship is moving close to light speed &1 second on spaceship is equal to 10 seconds on Sarah's clock. In 10 seconds spaceship would have travelled 10 light seconds. What speed will Adam calculate? 10 light seconds in 1 second, that would be 10 times speed of light?
Eugene, how would one go about measuring the speed of his ship and know he's near C? Is it even possible?
What if adam shines a laser forwards instead of walking/throwing ball? Would the laser to adam move forwads at the speed of light? What would Sarah see?
This is explained in detail in the video at th-cam.com/video/ev9zrt__lec/w-d-xo.html
Why Adams motion alone is dilated, even the spaceship is also moving at a speed nearer to c, why doesn't the movement of the spaceship appears to be dilated
I read some pages on a book and some other references regarding time travel, it says that time travel is possible if we can build a time machine that can travel faster than speed of light so my question here is:
Is it true that if you travel faster than speed of light you will be travel back in time? my point here is time travel to the past
+Jet Cannon u need to understand lorentz transformation equation for that. its not that easy or intuitive thing unless you are really passionate about math and physics
Like varun swamy said, you have to understand the Lorentz transformation. But the equation isn't that tough to understand. For any moving object, you multiply its time, its length, and its mass by 1/√(1-v^2/c^2), where v is your velocity and c is the speed of light. As you can see, once your velocity equals c, then you end up dividing by zero, so everything pretty much breaks down there. And if your velocity is *greater* than c, then you end up with an imaginary number in the denominator, which isn't much better. And even if you ignore all that and just say "v greater than c equals negative time! So that must mean traveling into the past!" it still doesn't make much sense. That's also the factor by which your length contracts, so do you start to stretch out when you go faster than c? Or do you just gain negative length? What does that mean? And negative mass too? Not a very promising time machine.
Fantastic info Eugene, it makes for very easy understanding :)
+bonetiger8, glad you liked it. Thanks.
what if you had two quantum entangled particles one on the spaceship and
one on the earth and he fires a particle forward effecting the spin of the
entangled particle which instantly effecting the other particle so in
his time frame he send a particle at the speed of light forward and
Sarah recorded the time when the quantum spin state changed and then
could add both his speed plus the speed of light together doubling it
does this work?
Remember, different observers will disagree about whether or not two events happened simultaneously.
What about two ships flying towards each other at the near speed of light? Doesn't that exceed the speed of light when they cross or what happens exactly?
They will not think the other spaceship is going faster than the speed of light, because they will think that the Universe is length contracted.
@@EugeneKhutoryansky That makes sense, thank you for replying!
The crazy thing is, according to the theory of relativity, even if Adam is moving at a speed close to that of light (mind you, not equal) and Sarah is at rest, they will both find the speed of light to be the same, is: 2.998792458 * 10^8 m/s.
what if two spaceships would fly at each other at the exact opposite flight directions and each spaceship is moving at the speed of light doesn't it mean that the relative velocity of those ships is 2*C?
Nope! Time dilation prevents that from happening.
I feel like the point is that if you do go faster than the speed of light, you cant prove it to anyone so dont bother telling them lol
What if Sara starts walking backwards? wouldn't she see Adam passing the speed of light?
Time will run backwards. So Adam will move backwards. No way passing the speed of light.
If we want to go "faster" than light, we stay still and expand and contract the SPACE around the ship because space can do what ever it wants. That is how the warp engines in Star Trek work. Expand space behind, contract space in front. And that's how to get to Alpha Centauri, 4.37 light years away, in a matter of weeks.
+Cameron Hawkins Using the warp drive also wouldn't lead to any time dilation so you could return to Earth without everyone you know aging dramatically.
If Adam did go faster than the speed of light, would Sarah see Adam move in reverse/rewind?
Sarah wouldnt see Adam at all since no photons would be able to scatter off his spaceship and go into Sarah's eyeballs.
Adam's ship is getting better and better :)
***** This video needed a bigger spaceship, so that Adam could walk inside it.
***** But i like the coloured clock.
Adam's clock is slowing down because the photon is having a longer distance to travel to reach the detector. Firing photons from both directions towards the middle and comparing the differences in frequencies will fix the problem.
That is actually a different phenomenon. I discuss that in my video at th-cam.com/video/ruRrVWHcgws/w-d-xo.html
@@EugeneKhutoryansky its the same phenomenon. You are still making the same mistake.
The photon from the center ship will reach the trailing ship first as that ship is moving to meet it.
This is not a mistake. What you wrote is exactly what I showed in that other video.
@@EugeneKhutoryansky you showed the photon reaching the front and back ship at the same time. That doesn't happen when the ships are in motion.
It depends on who's point of view you are talking about. From the perspective of a person inside one of the spaceships, the spaceships are at rest.
что значит быстрее света
относительно чего?
i dont understand why we cant travel at the speed of light>??? Eugne Any helpSir?
Time slows the closer you approach the speed of light according to mass. (the more mass the slower) Light has no mass (or almost), which is why the higgs boson particle can exeed the speed of light. (it has no mass)
+Apoorva Gupta in earth many things travels at speed of light
+Apoorva Gupta watch lecture series by prof. shiva prasad from iit bombay on special theory of relativity. trust me, if u give some time to it, u will def understand it from this lecture series. all confusing things are explained quite intuitively and comprehensively
Spaceship moving at the speed of light. Photon #stillwinning
Great vid as always! :)
A glass plate's thickness dictates the amount of reflected light. Some light scatters from the upper surface, some from the lower surface. According to QED, the upper surface reflection is affected by the distance to the lower surface. Since the upper surface appears to instantaneously know the distance to the lower surface, here is my attempt:
A veeery thick glass plate with a variable thickness mechanism is placed between two planets. Light is shone on the upper surface and the amount of reflection is detected there. Could another person with the variable thickness control, on the other side of the glass plate, send instant morse signals in reflectivity?
No, but you're trying to invent something that would, quantum entangled networking aims to do something magic like it
If the spaceship is travelling at the speed of light, Adam will not move for Sarah, so he can't go faster than light. Ok, but the spaceship is already flying at the speed of light. Isn't it violating the relativity? it was just a fictional situation, because It's not possible to travel at the speed of light, right?
Rodrigo Appendino That is correct, it is not possible to travel at the speed of light, but you can approach arbitrarily close to the speed of light.
Rodrigo Appendino Well, problem is, he can't. It's simply nonsensical to say that something "travels at the speed of light," unless it's a massless particle.
I know, markus
time = motion. no motion = you stopped the time. you replay the motion in reverse manner = you reversed time. and the same for fast forwarding time. living organisms are hard to predict because their motion depends on brain decisions and not solely by the law of physics to get to a certain point.
can someone answer me please :one of the rules : that the speed of light is equale for all observors... but in the video here adam is at very fast speed and he sees the light as its moving sloweky not on the speed of light !! so for adams point of view the light is moving with a little speed which disagree the rule !can someone explaine please
Adam still sees the ball of light moving at the regular speed of light. This is because to measure this speed, he needs to use his clock inside the spaceship, and from the perspective of everyone outside this spaceship, his clock is running very slowly.
@@EugeneKhutoryansky
i still didnt get it sorry...i think i need to understand the nature of light first before getting to understand this
but anyway thanks for the quick respond i appreciate it
2:01 "If the ship's speed EQUALS the speed of light, Sarah will see time inside the spaceship stop completely, and she will see Adam's walking speed decrease to zero.
Therefore, Sarah will always see Adam moving SLOWER than the speed of light."
So the ship EQUALS the speed of time. Even if Adam keeps sitting or standing, Sarah will see Adam moving together with the spaceship AT the speed of light.
Isn't it? If not please explain why.
And BTW, you forgot to mention that if the ship's speed EQUALS the speed of light, it will have to stand against all the (extreme blue shifted -> gamma) radiation of the whole universe at once, since the distance shrinked to zero. IMO this is the challenge we will never ever be mastering, even if we are able to reach 99,9% of the speed of light.
The speed of the spaceship can never actually reach the speed of light, due to the fact that the spaceship has mass. But the spaceship can approach arbitrarily close to the speed of light, and that is really the scenario I was referring to.
i understand. and hey THANKS for being there for us viewers and answering our questions! i do appreciate that much.
what if adam will emit a laser light forward? how will sarah see it?
Sarah will see the laser move at the speed of light, the same speed as that ball of light outside the spaceship. Whenever different observers measure the speed of light, they always get the same answer even if one is moving relative to the other.
what if adam shines a torch???
There's a small inconsistency at 2:07, I think. If the spaceship is moving at the speed of light (assuming that's possible), then the photon should not be moving forward in the animation (ie. moving faster than the spaceship).
The spaceship is not moving at the speed of light, because objects with mass can never reach the speed of light. But, they can get arbitrarily close to the speed of light, and that is what I was trying to show. Thanks.
@@EugeneKhutoryansky You're right of course, and it's clear to me that that's the point you were making. It's just that the video explicitly explores the scenario where the spaceship travels at the speed of light (surely because it was necessary to show that you can't (theoretically) make a step forward at all at the speed of light to break it). Assuming that this was possible however, the photon should be moving at the same speed as the ship.
Also, let me take this opportunity to say that I've been watching your amazing videos throughout the years and they really helped me better understand physics! I really appreciate your work, thank you so much! 😊
Thanks for the compliments. I am glad my videos have been helpful.
sorry to see Sarah so emotional about it
Speed of light depends on its medium. Space in a galaxy is denser than outside galaxy. Therefore speed of light in free space is greater than on earth.
By the phrase "speed of light" I am referring to the speed of light in a vacuum.
What if photons have an infinitesimal lifetime but they don't decay in other particles because they don't feel time?
I know it makes no sense to a particle that not experiences time to decay, I was just wondering.
in other words, Adam will lagg for us
Thanks for reply
In your video u says that adam is in spaceship and he throughs the ball forward(or walk forward). In my queastin adam is in space ship but sara through tha ball backward(or walk backward).
According the theory, sara feels that adam's time is moving slow so adam feels that sara's time is moving fast. And if sara through the ball backward(or walk bacward),
Due to fast moving time, ball is going fast. So according to adam's view sara is moving backward nearly the speed of light and through the ball backward so ball is going faster than light.
ashish nigam No, Adam does not view Sarah's time as moving fast. Adam sees Sarah's time as moving slowly. Both Adam and Sarah view the other person's clock as moving slower than their own. If this were not the case, then it would be possible to tell who is moving, which would violate the founding principle of Einstein's Theory of Relativity.
Eugene Khutoryansky thanks now i can understand
Eugene Khutoryansky then according to photon perspective i m going with the speed of light and my clock's tick stop.
And if sara and adam both feel that other person's time slower than thair own so both feel that they r older than other. Then who is in future relative to other.
And if i wish go into future so if i will go with speed nearly to light then i will see that others person's clock slower than me so they will going in future not i.
And according to others i m in future.
Totly contradictid.
Is there r any proof of ttheory of relativity???????
Eugene Khutoryansky and who is going into future relative to others??
Sara or adam
ashish nigam I cover that question in detail in my "Twin Paradox" video. You can find it in the links at the end of the video up above, or from my TH-cam home page. Thanks.
This is scary, it's like universe is trying to stop you from passing the speed of light
I have predıcted with my theory and my formula 6.3 tımes greater than the speed of light, which is measured as if apparently inside of M87 black hole. I SUGGEST HAVING A LOOK AT THE FIRST PART OF MY THEORY AND MY FIRST FORMULA WHICH DETERMINES A LINEAR VELOCITY OF...6.3 TIMES GREATER THAN THE SPEED OF LIGHT, ETC. AND I TOLD WHERE OUR MEASURED CONSTANTS ARE ROOTED IN. We need to change the concept of matter that makes us imprisoned by all kinds of impressions and especially by accepting the vacuum illusion which it has been sitting comfortably in it
My mind can't seem to grasp that concept, or anything of relativity for that matter, can you explain differently?
Nothing can not go faster then the speed of light. But the thing is the space the mass is passing though is a different thing at the moment space is expanding faster then the speed of light So the only way to move though space faster then the speed of light is to shrink the space the mass is passing though
How to go faster than light ,
Travel at the speed of light, time becomes 0, speed =d/t, speed becomes infinite
(It’s a joke)
I think adam's spaceship upgraded in this video.. 😂
Wonderful.
Danny Criss Thanks for the compliment. I am glad you liked it.
Thanks for the video!
Thanks.
But Adams space ship cannot reach the speed of light without crushing. Therefore you cannot reach it.
Adam has a very nice spaceship and it would be a shame to have it infinitely massive and all crushed and stuff.
Wish my space ship was as badass as adams...
If sara through the ball in opposite direction of adam. Since sara's time faster than adam. And according to adam's perspectiive he is still and sara is moving nearly the speed of light and she throughs a ball and her time faster than adam then it looks like ball is going faster than light (according to adam's perspective).
And according the logic of twin paradox sara's time never slower than adam's
And if u say from adam's perspective that sara's time go slower then adam's then it is again creat twin paradox.
And sorry for my english
Waiting for your answer
ashish nigam I am not sure if I understood your question properly. From Adam's perspective, he is standing still. Therefore, no matter what direction he throws the ball, he will always think that the ball is moving much slower than the speed of light. If this doesn't answer the question you were trying to ask, please let me know.