Bending both Space and Time - Ask a Spaceman!
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- เผยแพร่เมื่อ 20 ต.ค. 2024
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How did Einstein develop General Relativity? What does it mean for different kinds of masses to be equivalent? How does gravity do what it does? Why is curvature so important in understanding gravity? I discuss these questions and more in today’s Ask a Spaceman!
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Keep those questions about space, science, astronomy, astrophysics, and cosmology coming to #AskASpaceman for COMPLETE KNOWLEDGE OF TIME AND SPACE! Music by Jason Grady and Nick Bain.
I like how u used the example of the dog with the cone to explain perspective
This is hard. Sometimes I feel like I am about to grasp it, then it slips away.
Thanks for sharing:-)
It's definitely slippery stuff...don't give up!
They believe in ridiculous virtual particles.Jesus walks on water is more realistic.What is virtual?Maybe video games.Then we live in video games.I am in one universe and other me is in second universe etc.Did you see that staff is the same like Bible.
Thanks for taking the time to explain that properly.
Thanks for watching!
You have become my favorite "Explainer " of science that is hard ie: Relativity and thought experiments I had never known about. I'm a composer and I know about content. It's hard but thank you
Thank you, I really appreciate that!
This helps me to understand the special dimensions and how spacetime is bent. Thanks Paul! You're AWESOME!
The video about bending space and time showcasing geomatry cause by gravity in general relativity is intrinsic with no 4th dimension and static curvature of space including the light cone was interesting to view. Thank you Sir.
Hi Paul!
Can you please make a video about double slits experiment.
It seems that there is something more over there that meets the eye.
Thanks!
Will do, it's on the list!
"We'll have a happy ending for the dog as it flies past the sun." pretty sure there are no happy endings in store for that poor roasted pooch. XD
best example of this I ever saw was from an 8th grade science teacher. she had a large styrofoam ball painted yellow(its a star). instead of sitting on a sheet she had a wire frame around it with all three dimensions shown. it had 3 wires that were only connected at their ends, all the cross sectional pieces were carefully missed with them to give a clear path. a thick washer was on all three. each one followed a curved path around the "star" in a trajectory that followed a different axis. one came up from the bottom, another came to the front from the back and one went from left to right. never had the 4th dimension problem because I always understood it in 3d. she also used it to explain time dilation though she didn't go into huge detail.
How did she use that to explain gravitational time dilation (I say *gravitational* time dilation because there is also velocity-dependent time dilation that does not seem to be what was described in this thought experiment)?
Rather than a flat disk getting bent into a drain to represent the curvature of space would it be more accurate to think of space as a 3d grid where the cubes get smaller towards the center of a massive object but the volume of space for all the cubes is the same? Would it also be accurate to dilate time so that it looks like it's passing slower for objects that get closer to a massive object?
6:47 "We'll have a happy ending for the dog that's flying by the sun."
Not sure it works that way 😂
Dogs flying by the sun never have a happy ending.
All dogs are flying around the Sun, as are we.
No close. And we have this precious biosphere. I hope it can keep it.
Space dogs will be fine as their cones will shield them from the radiation.
You're AWESOME Broseph!!!!!!!! Please keep making easy to understand videos for Couch Scientists like me😎
I plan on it, thanks :)
Thank you so much for making this video. Its very useful and enlightening. I have a few questions:
1. How does a planet or star or any massive object communicate its properties to the coordinates of space-time telling how much static-space and the light-cone should deviate from the "flat" space-time in that particular point/position in space-time?
2. Does this imply that every point in space-time has the information of every massive object in the universe (and will therefore bend/succumb to its presence/vicinity)?
If #2 is true, then it would imply that every point in space-time is "entangled" to every other point in space-time, and entanglement is not necessarily a particle-based phenomenon.
3. Also, if you know, could you please tell me: if particles are entangled by some process, is there a way to un-entangle them or break their entanglement?
4. I was reading another article which said that gravitational waves travel at the speed of light. Does this mean that the change in mass of an object due to a non-elastic collision would result in space-time changing its properties depending on how far the object from the point in space?
5. If the big-bang theory is correct, and space-time emerged from a single point, would this not imply that all space-time is entangled?
All your help is most appreciated.
Best Regards,
Aby.
Is GR time-symmetric, the way that Newtonian gravity is? On one hand, it seems like the past light cone would bend in the same way as the future light cone in the presence of mass. On the other hand, time symmetry when you're bending time seems confusing, and I'm not sure how time reversal is supposed to work with an event horizon.
This is phenomenal dissemination of information. I can actually absorb the material. Thank you much.
I have a question. If it is the same time in 3 galaxies, A, B, and C. We are in B. A has super low gravity, C has super high gravity. After a minute in B, would a stopwatch triggered at the same time show more time elapsed in A and less time in C?
Thanks, I really appreciate it! Here's a handy guide; moving clocks run slow -> accelerated clocks run slow -> strong-gravity clocks run slow. Hope that helps!
Paul M. Sutter Haha! I like it! Thank you. :-)
@@PaulMSutter Do strong gravity clocks look like the are running slower from the perspective of clocks located in less strong gravity locations? Do weak gravity clocks look like the are running faster from the perspective of clocks located in strong gravity locations?
why this curvature of spacetime is affecting moving things differently according to their speed or mass?
The "altering the direction of the lightcone" bit depends on an object's mass.
And that's all great there's nothing wrong with that... except there's some things wrong with that. I love it lol
I have a question about gravity and time dilation. I have a small thought experiment for you. If I spend my life in space in a craft that spins around its axis to give me normal earth gravity, will I experience the same time dilation due to my apparent gravity on my space craft as I would on earth due to its gravity? Ignore any additional time changes due to my orbit around the earth; perhaps my ship is in a stable orbit at L4 or L5. And if some mad scientist decides to turn up the spin to 10 Gs, would I again experience time dilation as a person on a planet with ten times earth's gravity? Would the speed of my spin around the axis add to the complexity, or is this where my time dilation would come from? Thanks
It turns out hat rotation is the same thing as acceleration which is a different force to gravity (inertia). It is sometimes considered an equivalent to gravity but it is not a result of mass.
You might say first or second ... but from which observer's frame of reference was that measured?
I prefer to think of the bending of space-time as a density; the deeper in a gravity well, the more dense space-time is. I know it's not right, but I find it more useful for visualization.
Also, woof! Woof! Woof?
Can you say something more, why imagining spacetime curvature as density is not correct?
One possible reason could be that density is a scalar, while to describe the curvature you need all 3 dimensions (a vector). Note that curvature is in fact an acceleration of the spacetime (aka gravity).
So with the density itself we would have the same problem as flat-earthers (a small but loud community of mentally retarded people who think that we live on a pizza under a dome, gravity doesn't exist, everything is driven "down" by density, etc.). They need an universal "down" instead of gravity vector.
One possible way out of this problem would be to imagine the curvature as a density gradient. Then the density would probably substitute mass/energy as a cause of gravity probably with a different distribution in the spacetime (not sure about the last).
KUDr below gives some good reasons; but my main reason is with the word itself. Density suggests a tangible physical presence. And we shouldn't ascribe that to space-time.
TY. Well explained & interesting. So the light cone gets rotated. This is helpful. it gets rotated because it follows a geodesic on a curved spacetime
I dunno why your saying there's 2 different things: the cone being rotated + spacetime curved. They seem to be the same.
& spacetime is curved by energy/mass/matter due to wizard magic but we don't know who the wizard is. OK got it. Thanks again.
Another great video.
I have a question. Does an electron jump from one energy level to the next without being inbetween?
That's exactly what it does, and what is meant by the word "quantum" :)
Paul M. Sutter That throws me for a loss. I understand the wave function but this just seems weird to me. Pilot wave theory does not explain this. I do not have a physics degree but have been studying particle and theoretical physics on my own for five years now and quantum mechanics is just plain confusing. Quantum entanglement evidently has been proven and now this quantum jumping. Hmm, I guess that energy, forces, and fields at this scale has us temporarily stuck since are ability to measure at this scale is pretty much at a standstill.
+constellationpegasus
As another example of quantum phenomena:
electrons have what we call "an elementary charge", meaning that it is the lowest possible denominator when it comes to particles having a charge, meaning that there is no 0.5 charge of an electron, or 1/3. It's always in integer multiples of electron's chrage.
Perhaps the electron is a cloud and just focuses the cloud higher in the atmosphere of the atom when it has higher energy. I wonder how we determined the difference between quantum tunneling and just cloudy things focusing at different places. Perhaps the higgs field is the circuit board for the universe turning the lights on and off in space.
The Museum or Physics Lab demo with a piece of stretched fabric and a heavy ball in the center bends the fabric downwards towards the gravity of the earth. In reality, a massive object like our sun should bend Space-Time equally all around it. So is there an Up or Down in Space-Time?
I think a cubic meter of space is smaller the closer you get to the center of a massive object in all directions around it but it's the same amount of space as the bigger cubes farther away.
The light dawns. Not that I understand in my bones, but at least in my head. I think you may need to put more emphasis on how counterintuitive it is and how that is not relevant.
It would certainly explain in a universe this size how it would ever be possible for Wormholes to connect two ends of the universe together at all if possible
If you are a beam of light or a photon, starting from when you are created, you will arrive at your destination instantly, not in x years
So light travels faster than the speed of light from the light's point of view?
Paul.
I think we are all struggling here. I'm again lost. The last, or whatever Discovery show, explaining these "simple" facts, in a story about Einstains life made me belive I had it. But not any longer.
I do understand we have to add light to that thing at the museum. But from there it's not that very clear, still.
I hope you can have a new go on this very important part. I have been watching the same clip 3 times by now. but still..
Thanks!
Are you saying gravity will also bend light (which I have no issues to understand) and on top of that adding time? (Still struggling after my 7 watch trough, and I really need to understand this)
I understand how this universe happened to be through the big bang, I don't want call it theory as all the evidence is there, (We are lacking a small piece to see what happened at "0"
With my knowledge above I understand how all the matter our universe is built upon came to exists.
(Although we can't yet explain dark matter, we just know it's there, so far)
I understand how life has evolved on this planet, thanks to Darwin and people after him explaining it again.
Gallielo, Newton and many others enligthen us, and it's a bit strange we still use some of Newtons math in 2018. With strange I mean such a brilliant mind was born way too early to be understood.
I understand the physics behing a A bomb and a H bomb. (And hope we soon will be able to facilitate fusion power on earth)
Back to this lecture :-) Gravity will bend light. Please take it from there,
Thanks again
I don’t get it, I wish, I did, but I fear, I don’t have the time to learn the math, nor the brains to comprehend. When they speak about our four dimensional spacetime, it’s kind of perplexing, because I only see three. Sometimes I wonder, if you could say, that we don’t see time, but we do experience time, and this experiencing of time is the fourth dimension? I also wonder whether the general theory of relativity isn’t ‘just’ a geometrical, mathematical description/interpretation of what gravity is. I remember seeing a video on pbs spacetime, where they explained, that the speed of light really wasn’t about the speed of light, but about the speed of causality. Sometimes I wonder whether, what general theory of relativity describes as the curvature of time - what ever that might mean - might as well be described as the dilation, the hesitation of causality, a hesitation that increases at close to light speed, and close to massive objects. Somehow I feel I can imagine a curved space surrounding heavy objects, and then the other thing that happens is just something with (the speed of) causation.... but then again, I don’t get the description of gravity on the surface a neutron star... Gravity, I just don’t get!
I think gravity is the curve of space-time. When you look at an eclipse of the sun by the moon you see stars behind the sun that are not in direct line of sight because the mass of the sun is bending space around it. Objects appear to be time dilated and slower as they get closer to massive objects because they are moving through the same amount of space but the space is more dense.
Whoa, for once you didn't break my brain. This conception is more inline with my own understanding. The classic explanation and demonstration of curvature never made sense to me ("that's not how this works, that's not how any of this works"). My physics background is limited to Intro to Physics, and that Prof didn't really spend too much time trying to explain the concept. So, I just played around with the idea in my head till it made sense.
Glad I could help!
At the end of halfway in, out begins. It doesn't happen at the surface.
❤
I still don't get how the static curvature of space is intrinsic. I can see how the curvature of time can be intrinsic but not space. If space deviates even sightly from being euclidian at a point it seems to me like that should necessitate a 4th spacial dimension.
Also, can we please stop calling time a dimension? At least we should always clarify that it's not a spacial dimension but a temporal one whenever possible in videos like these.
If time and space is connected, is there a bend out in space
Nicely done. Would like to have seen the cone structure on the black board.
I would like to be able to draw :/
What if there was no need for a Multiverse, what if the singularity points of all the black holes in the universe all pinch together and our universe is pinched together or folded, an an infinite number of times, any 2 points in the universe can touch at any given time?
Well they definitely touch in terms of time and all dilate the entire future heat death of the universe down to an episode of Lexx but I don't know which would be a better show.
i STILL dont get it
I'm sorry I meant no need for the extra hidden dimensions
Aha, so that's why clocks are round!
So what is the thickness of space-time ... so it can bend into itself...IS it bend into nothing-ness ?? like universe begin from nothing...
Spacetime is just a set of coordinates. Don't worry too much about it :)
If space is flat, then how flat is it? If its flat, then it has to be less thick than its long. So how long is it? If a heavy object bends space-time it should bend it equally all around it and not have that "falling" into effect like the Physics Lab demo using a piece of stretchy fabric.
Yea I agree completely. A lot of these examples has been dumbed down to such a degree that they kinda start working against the main purpose of providing understanding of the concepts in question.
Einstein is a bit more confident than a primary school student when he figured out the spacetime fabric is elatic in the calculation of speed of an object. The speed of light always remain constant in whatever location of observation, the complication came from the distance and time of two objects(one the light), and light insist of no change in its speed at all. Einstein insisted the calculation of speed by the wellknown distance and time relation by integrating the distance and time into one single formula set up by the right angle triangle. He successed in solving out the algerbric relation of the feeling of time and distance in between the two objects, unveiling the texture of spacetime are of elatic nature, which is extremely astonishing even from today point of view. In later Special Relativity, gravity is explained by the distortion of spacetime between objects, and human could experience the different degree of distortion in the magnitude difference of our body weight, the foundation of the taichi internal kungfu skill, qi by body weight.
He never fails to get me to laugh at one of his expressions or gestures. Very good teacher. But he can't afford visual aids?
You seem to be FAIRLY young. It's nice to see someone as smart as you without being an old man. props.
Thanks! I went to school.
You can imagine the light cone as the lines you see on display sitting in car driving rearward. These lines show you the limits
If space is flat, then how flat is it? If its flat, then it has to be less thick than its long. So how long is it? If a heavy object bends space-time it should bend it equally all around it and not have that "falling" into effect like the Physics Lab demo using a piece of stretchy fabric.
I think three dimensionally flat means the square on one side of the cube is the same size as the square on the other side of the cube regardless of how big that cube is. Perhaps we just perceive it as flat because we're inside it.
I tried that during the time the veil between earth and spirit world is active. I was only able to bend 2 seconds from every 60 minutes.
Second
How can all you smart guys know how to solve the Einstein equations, but you can't figure out how quantum gravity works, and how to bend spacetime using technology? Is it not so obvious that quantum entanglement has something to do with spacetime.
First
Tony Lambregts Wrong. I can bend time so I am first.