history of the speed of light and how its speed was determined
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- เผยแพร่เมื่อ 29 ก.ย. 2024
- What is the history behind determining the speed of light? How did past scientists determine it'salue value
This video covers Rømer, Bradley, Fizeau and Foucault and how they determined the speed of light.
CORRECTION: As some have noted I have made an error in the discussion on Rømer. I acknowledge this , and here is my correction as well as animation: • Ole Rømer correction
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Just a note to say thank you! This was a great video. Have subscribed. Keep up the excellent work!.
Thanks Daniel
Maybe the scientist of that time didn't know about the earth orbit is in elleptical path and this also could be the reason for the change in interval of time for stars circular rotation and jupiters moon rotation period.
Which means why we thought light to be travelling still has no base for it.
@@PhysicsHigh llllllĺĺllllĺllllll2
@@AbhayKumar-um8vl It demod that light IS traveling, and that was possible w/o great accuracies.
Lol, we dont today depend upon 18th century observation to determine whether or not light is traveling.
The discrepancy was that in the 17th century they didnt have a very accurate figure for our distance from the sun.
Btw, earths orbit is VERY circular. The minor axis is only about 1/7000ths shorter than the major. That fact makes so the earth varies (in distance from the sun) by only about 3.3%
You will be surprised that combined with Newton-Laplace formula for a wave speed in any medium, it solves gravity - no more GR needed. Read 2-page chapter 92 in "Time Matters, 9th edition": gravity (acceleration g) is directly related to time dilation D (and nothing else) g = -(0.5c²/D²)' ≈ c²×D' ~ ∇D - formula from that book back-cover.
Thanks for not disturbing your interesting story with background music.
they do that so your brain is distracted by irritating music so their garbage enter your memory by passing your critical sensors which discriminate between some thing useful and their crap.Ferydoon Shirazi. MG1
Amen...!
@@primemagithat's not why we do it tho 😅
The music is added to combine it all together and hide for example background noise.
@@MrSorbiasIt makes videos impossible to endure - such a shame when the content is otherwise good. (Dot)
Thanks for the wonderful video, and a huge thanks for not ruining it with crappy background music.
I don't know why some people are compelled to add annoying background music throughout their videos.
I always let content creators know that I didn't watch their vid because of an added soundtrack. It's constructive criticism, not bichin.
Thank you for great video. We learned about the early scientists at school, and I was amazed, and still am, at the intellect and the determination of Rømer, Bradley and Fizeau, and many others, using basic astronomical equipment etc. I mean, if I'm correct, Fizeau's mirror was five and a half miles away, and he was using something like an oil lamp or a candle. I know there was not a lot of light pollution in thise days, but still!
very nice video, I've been getting questions about this and may adapt it for my channel.
For his experiment, Michelson built a hollow tube about a meter in diameter and about a mile long in what is now Irvine, California. It's part of the history of Southern California.
The tube (a pipe) was pumped down to a vacuum. Does it still exist?
This is brilliant.
I’m sorry but the first explanation about Ole Romer’s observations are a little bit misleading: even when observing from really far the period would me almost the same. But adding up these intervals would seem a bit late comparing to observations when earth is moving away and a bit early when approaching again.
Did you see my errata fix? It’s linked in as well as in the description
Need to know more please
Hi Paul, thanks for another fantastic video! I think there is a slight error in your explanation of Romer's data... the apparent period should depend on the relative velocity of Jupiter/Io and Earth, not upon their distances (as suggested at 3:05). This would mean the apparent period is larger when earth is moving from J to K, and smaller from F to G. Consider: if Earth were *stationary* at K, the apparent period would = true period, despite light taking longer to travel a greater distance. It seems analogous to the Doppler effect: when source and observer are moving apart, the apparent f decreases (hence apparent T increases)
Thanks Alex. I stand corrected.
@@PhysicsHigh This part of your explanation bothered me too.
I'm not sure if the changing relative velocities between earth and Jupiter were enough to account for a large enough time difference - it's not difficult to do the math and check what that time difference would be, so I could be wrong.
But a simpler interpretation of the story doesn't require this: If we assume Roemer established the approximate period over several measurements taken while Earth and Jupiter were closer to each other, all he had to do was mark his calender at equal intervals into the future (with each interval being the period he observed) and then look at Jupiter when those times came.
So if for example the measured period was 45 hours, he'd mark his calender at 45 hours in the future, 90 hours in the future, 135 hours etc. for several months ahead.
If he came back and checked he'd discover that for the near future his predictions were reasonably accurate, but later in the year they were several minutes too early.
Similarly if he started out determining the period when Earth and Jupiter were far apart and then marked his calender at equal intervals he'd find that after a few months those predictions were too late.
This seems to me like a reasonable interpretation of what happened, based on the familiar points of the story.
Edit: also @14:55 please correct your units. The first number should be in m/s.
...and I am working on a fix.
Here is my correction: th-cam.com/video/TAIlswch5d0/w-d-xo.html
THANK YOU SO MUCH I WAS SO CONFUSED AS TO HOW HIS EXPLANATION WOULD HAVE WORKED
Just letting you know I am currently working on a follow up to this video with more recent experiments on determining the speed of the light. Stay tuned
Both follow up videos have now been released. Check the descriptions or end screens
Great! I'll do that. Thank you. Best Regards Dan.
Well, whoever built the great pyramids of gezza, knew the exact speed of light.
And also the meter.
My high school physics teacher explained Foucault's method to me in 1983, and it was my first experience of finding out that something that seemed unknowable to mere mortals like me was actually a simple matter to explain and understand. I had that same experience again as an undergrad when I asked my biology prof how we knew about transmembrane cell proteins. (The amount we seemed to know about molecular cell structure baffled me.) In about one minute he explained freeze-fracturing to me. It was so simple! So I went into research.
I think people might be surprised how much they can understand if they just have the confidence to ask, and if they ask someone who is good at explaining things. Kids, ask your teachers how we know the things they are teaching! (But don't be a snot about it... that won't help.)
It’s all incorrect knowledge, and should be retracted. Roemer would never witness a delay in anything, because he was using a telescope.
@@ptgr12 People who have dedicated their lives to studying this stuff over the past few centuries, and who know a lot more about it than you do, overwhelmingly disagree that it's all incorrect. Odd are that there's something about this that you don't understand. That's the most likely explanation for your outlier opinion. You could be right, of course, but I think it's exceedingly unlikely.
Jesus Christ. You believe it? Isn’t that the one with the beam travelling 8 kms before electricity was even a thing? Did you hear that? Process it? It’s like you’re all brain dead.
@@beenaplumber8379 I am right. 100%, and all it takes is a little common sense, which is something lacking everywhere. Obviously.
@@ptgr12 Common sense is never common (varies by cultural & personal differences), and it is not useful as evidence. So far the only case you've made is that your brain worked this out in a certain way that makes sense to you, but no one else. But you're 100% right. Science doesn't work that way. Maybe science isn't your thing?
In an episode of the television series Bonanza ("Look to the Stars", broadcast March 18, 1962), Ben Cartwright (Lorne Greene) helps the 16-year-old Michelson (portrayed by 25-year-old Douglas Lambert (1936-1986)) obtain an appointment to the U.S. Naval Academy, despite the opposition of the bigoted town schoolteacher (played by William Schallert). Bonanza was set in and around Virginia City, Nevada, where Michelson lived with his parents prior to leaving for the Naval Academy. In a voice-over at the end of the episode, Greene mentions Michelson's 1907 Nobel Prize.
I remember this one. A cowboy show with physics!
The speed of light was a theoretical thing in those days. Nothing to do with everyday life. Now, the speed of light is factored into z lot of technology we use every day.
@@daleeasternbrat816 I know that!
Timestamps for each speed of light experiment
Ole Romer 1:04
James Bradly 5:12
Hippolyte Fizeau 7:53
Leon Focault 12:15
Vedas said first
Thanks
This is amazing! This video definitely deserves more views! Thank you.
Worth mentioning : XVIIth century judge Fermat (of famous math conjecture fame) had the intuition that light takes the shortest route in TIME between A and B. This implies a finite speed. From this principle, Descartes and Snell independantly derived the law of refraction, fundamental to lens design.
A simple way to test the speed of light is to try and open the refrigerator door before the light comes on.
It's actually faster because it's cooled. And everyone knows light travels faster in a vacuum cleaner and a refrigerator.
So if I open my fridge I could somehow deduce the exact speed of light? Lol
Or hit the light switch and be in bed before it gets dark.
Get through the road junction before you see the red light.
Excellent presentation! Easily one of the best I've seen on the subject. I'm just a hack layman on physics, but I do relish videos like this. Thanks a million!
That’s great feedback. Thanks. I do hope you share.
False. We have never determined the speed of light. We have only determined twice the speed of light divided by two. There’s no way (yet) to measure it in one direction or (yet) eliminate the possibility that some unknown universal constant has light moving at different speeds in different directions.
Suggestion. Please put captions. It was kinda hard to hear the names of the scientist you mentioned.
Its simple ele vara#$&*"&eee
Captions are available - you just click the caption icon
click the little "cc" button in the lower right of the video screen.
Wow. At age 65, I am suddenly a high school student studying a subject that teenaged-me dismissed as boring. Thanks for that!
How does being further away from IO make the period appear longer? Wouldn't the start of the period be delayed just as much as the end of the period?
Exactly right
Did you see my errata?
Except the speed of light c is really the average speed over a round-trip journey, and we cannot be certain that the speed is the same in both directions.
Light-Speed is measured by the around trip a+b=c.
Take away "a" light speed speed will change.
Good watch after videos about the Maxwell's equations and his realisation that light is but an electromagnetic wave.
Why do we pretend the speed of light is a constant when even in a vacuum in the best conditions we have access to the actual number calculated varies drastically?
Found a small mistake:
At 14:54
It's 299,792,472 m/s
not km/s.
Otherwise, awesome video! I want to thank you for it!
So, are you the one in highschool?
It seems like you're struggling with this!
A fabulously clear explanation of how Roemer calculated the speed of light! Worth it for that alone! Ty
Pog
India is like 🤣😂🤣🤣 kids we discovered 4000 years ago
This video deserves more attention. You guys really helped me with my uni report on thr measurment of light speed
Thanks sir! Will u be releasing more videos for physics hsc syllabus module 7? Really wish u were my physics teacher at school!!
Yes. I have already quite a few videos for module 7. See the playlist, but there is more in development too. Make sure you are subscribed and click the bell.
Thanks for the encouragement and share with your peers
Please take a look at Ole Rømer's wiki, if You're not already familiar with this amazing man. I promise You will find it worth Your time.
The real reason is as fallows. As the Earth and Jupiter move in their orbits there are periods when the distance between them becomes smaller, they are closing to each other, and there are periods where the distance becomes larger and larger. In both situations you see Io starts an eclipse and measures the time when it is visible again. In the first situation the light had to travel a shorter distance that in the second situation, so the eclipse is "shorter" than when the planets are moving away from each other. So the important factor is the relative movement between Earth and Jupiter.
Exactly right
Such a fundamental mistake seriously reduces the credibility of the video.
I love this video. I imagine the series is very interesting. Thank you for doing this.
I have a question about Romer's experiment. I'm pretty sure that the difference in time was about 35 seconds, but NOT longer at K and F than at L and G. Rather, L and K were about the same and F and G were about the same; however, L and K were about 35 seconds longer than F and G. This would be because on the F and G side the Earth was speeding TOWARD Jupiter while on the L and K side Earth was speeding AWAY from Jupiter. The 45-hour orbit allowed the Earth to cover about 2 degrees of the Earth's orbit, which is a significant distance--requiring about 17 seconds of time for light to travel. So on the F and G side the 45 hours is 17 seconds shorter; on the L and K side the 45 hours is 17 seconds longer.
thanks Howard, you are correct and my error, I am working on a fix
Here is my correction: th-cam.com/video/TAIlswch5d0/w-d-xo.html
This video is such a good explanation that you appreciate the genius of the scientists who study nature and become more aware of our universe. Now if we could have an explanation of quantum entanglement and quantum measurement like this, that would be brilliant. But the finest minds are still pondering what quantum mechanics means.
My first thought was about the attempt to measure the “aether” by Michaelson and Morley. I also thought of the slit experiment which shows that light behaves like both a wave and a particle. That always fascinates me.
That's the speed of light from where we live
If the planet was bigger the speed of light would be slower
From my understanding there is no limit to how fast something can move in space
Planets move over 1 million miles per hour
And there's Planets that moves thousands of times faster
Not exactly correct.
They calculated the expected position for a whole year and discovered an approx. 1000 second gap between H and E.
They messured this quite precise. Their knowledge from the distance from earth to sun was known less precise and estimated less than the 150 million km we know nowedays.
300 million km in 1000 seconds gives 300.000 km/s. Must say... the 212.000 km/s was a very good first calculation.
Our teacher loves to use your videos
A method to discover the one-way speed of light.
Does light have a tail?
If light has a speed limit, then it has a tail. If light is instant than the off is just as fast as the on.
To find out if light has a speed limit take it past that limit and observe. To get light to appear to move past its limit, if it has one, simply rotate it. If light has a speed limit, as the circumference of the tip of the light grows ever larger, depending on its rotation rate, the angle at which the light would appear to progress in a snap shot view changes.
If light does not have a speed limit the arc will always appear at a similar radius.
If and when the tip of the light that creates the arc, is appearing to progress at a 45-degree angle to its path, you are at its max speed. X=Y moving at the same rate.
One of many configurations in finding the one-way speed of light, may be done easiest in space: SEE DRAWING ONE WAY LIGHT SPEED BELOW.
Configure three satellites. One at center and two at a radius. Rotate a laser on a center satellite, and use the two satellites at the radius as targets. The targets are 49.85 and 45.85-kilometers radius and they are 4.8 degrees apart. This geometry will give you a 45-degree angle between the two satellites targets from the mean radius tangent of 47.85 KM.
It is believed that it takes light about .0001663 seconds to go 49.85 KM. in space.
Run the test, based on the believed speed of light:
Rotate and fire the laser: The light is traveling to satellite #2 and will be there in .0001663 sec., with the rotation of the laser at 1000 rev/per/sec it takes .0000134 sec to rotate the entire 4.8 degrees between the two satellites and at that point the light is then traveling at the satellite #3.
Conventional belief light travel times
49.85 KM in .000166281 sec
45.85 KM in .000152939 sec
.000013342 sec difference
Rotational speed to travel 4.8 degrees in .000013342 sec = 999.35 rev / sec
At the above rotational speed of 999.7 rev/sec the light would hit the two satellites at the same moment, if it is traveling at 299,792 KM/sec
Examples of other speeds:
Light at instant speed can never hit both satellites at the same time, as the light is rotating.
If Light were traveling at 250,000 KM/ sec
49.85 KM in .0001994
45.85 KM in .0001834
.0000160 difference, if the speed of light is 250,000 KM/sec you would have to have the rotation of 4.8 degrees in .000016 sec or 833 rev/sec
If Light were traveling at 350,000 KM/ sec
49.85 KM in .00014242
45.85 KM in .00013
.00001242 difference, if the speed of light was 350,000 KM/sec you would have the rotation of 4.8 degrees in .00001241 sec. 1074 rev/sec
Observations
The two satellites are at a base distance of 4 km apart and the apparent path of the light is about 5.665 KM apart. The tip will appear to travel 5.665 KM in .0000134 or 1.41 times the believed speed of light. But in reality, the light is traveling 4 km less than satellite #2. In the PDF the actual light path, if the speed of light is as thought, the path is shown in the cross hatched line. At two angles, one at the speed of light and one just below, with less that a 45-degree angle to its base.
If light is instant, the light will hit the first satellite at go, and the second satellite always at the rotational speed, no more no less, and can't hit them both at the same time. Rotation speed and the speed between the two satellites will always be the same. If light is instant, then the off is as instant as the on, it has to tail.
The light, if traveling at 299,792,000 and rotating at 1000 RPS it will hit both satellites at the same time, if not then adjust the rotation speed and or the distance(s) until that happens and then calculate the speed of light.
A clock is installed to time the satellite target impacts, so the rotational speed can easily be adjusted and tuned to the speed needed to hit the two in zero time. Once that is achieved the clock is no longer needed.
At the instant you fire the laser for a millisecond you at the same time are recording and entering into the equation the exact distances and angles to the satellites. It would be extremely accurate, down to a millimeter.
I chose to use 47.85 KM as the radius as that is very close to the speed of light at 1000 Revs per second. 47.85 x 2 x (p) 3.1417 x 1000/ sec = 300,660 KM/sec to the median circumference. 1000 Rev./sec is easily achievable, especially in space, the laser doesn't have to rotate 360 degrees, it only has to move the 4.8 degrees in the allotted times and or adjustable times. The laser only has to fire for a millisecond, so it could be a very high-powered laser.
This method eliminates the current objections to the use of clocks. The Einsteinian arguments against clocks are two-fold, one is syncing two clocks at different locations and the second is using one clock in a round trip, starting and stopping the same clock. The objection in the latter is not an objection to clocks / time it is only an objection to it being a round trip voyage. Which I believe is problematic.
In both those objected to efforts above, the clocks measure an amount of time of light travel. In the above proposed method, there is one clock that measures the rotational speed of the rotating laser, which measures Rev/per/sec. That clock in no way measures any distance in time of light. Another clock is used to tune the rotating laser to discover the one-way speed of light. Once the tune is complete the clock does not measure time. No current objection would apply to the above method.
If light is instant, no matter how fast you rotate the laser, it will never hit both satellites at the same time.
Perhaps far more interesting, if light does have a limit, then some light, if it has enough energy, from distant places is getting to earth appearing at an angle, or if you will, a shift
We always hear about newton and Galileo and Aristotle,never had I ever known about someone called foucalt ,lol...speed of light,something that we use in about 80% of physics numericals,don't you'all agree...hahaha
Excellent video, thank you, I now have a better understanding of the history. An interesting consequence of a finite speed of light; as demonstrated by Olaf Romer, the observed orbital period of Io slows down while Earth moves away from Jupiter (i.e. from L to K in the diagram at approximately 3 minutes in). It is interesting because, in an expanding universe, distant galaxies are apparently moving away with a recessional velocity dependent on the distance from the observer. Therefore the further away the galaxy the slower the observed rotational velocity relative to its actual rotational velocity. At the Hubble Sphere (HS), the galaxies should appear stationary. Galaxies beyond the HS should appear to rotate in reverse time order; if the recessional velocity is a real movement. I conclude that the movement is fictitious and that the redshift-to-distance relationship is due to a cosmological dilation of relative clock time over absolute time whose rate of change is inversely proportionate to one another. This produces a scalar model where time and distance change interdependently, keeping the speed of light and other constants of nature constant as the universe evolves. I would love to discuss this with someone better qualified as it may explain the nature of dark energy, and dark matter, and why we are seeing the most distant galaxies with the JWST that appear too mature for our current theories.
Nice video... thanks for your effort...
I did not know the period of IO was so short... ~45h
Nevertheless the period observed should be the same...
if the observer are closer... or distant from Jupiter...
I can only see how this values would be of a perceptible magnitude...
if there was a significant distance difference between the start and the end
of the observation of a IO period (not only ~45min)
The ~80º arc or Earth orbit you mention between points
in Ole Romer diagram is done in roughly 3 months,,,
About:
c=2L/t of Fizeau
t=2L/c of Foucault
Could you please elaborate on why 'c' was chosen for the name?
c stands for celeritas, which means swift in Latin .
@@PhysicsHigh Which is also where we get 'acceleration' from, it means an increase in swiftness.
@MichaelKingsfordGray Accelerate comes from the Latin word 'accelerarre' which is derived from the Latin words 'ad' (meaining 'towards') and 'celere' (meaning 'swift'), so the literal meaning is 'to move towards swiftness'.
Light can't have a speed- 'light' can only be a rate of induction. The only way for light to have 'speed' is to attribute fake 'mass'.
Thank you magical unicorn 'photons'. If you are real, ease stop conveniently disappearing. 😂
good history, but real light which is a train of photon has physical structure which is disk shape. Man's current speed is taken horizontally on Earth two way divided by half. it is nearly correct on earth boundary. DLR, ESA, NASA has refused to check the speed from Earth to space and from space to earth one way. our test showed the speed is not constant because of shape of photon. gravity has very little effect on photon from side on earth, but has maximum effect from front and from behind of photon in space. the only reason I found for refusal is, they need to do real science to replace the current agreed assumption belief(good by space time). Eddington bending of star light was due to space dust interaction(reflection/refraction) not due to gravity. no space dust = no bending of light or lensing effect.
Full science information in my 1975 Bremen Summerhouse notes or by official request only. Ferydoon Shirazi. MG1
Thank you for the video. However, I'd like to share some important fact at 14:45 if I may. James Clerk Maxwell wasn't calculating the speed of light. He was calculating the speed of how the 'elecrto-magnetic' force is propagating throughout space according to his new-born theory. It was only after he came up with the result and compared it to what was already known, and this way, he become the first man on planet Earth to realise and undarstand that light is 'just' electro-magnetic force. It must have been an important day in his life.
Why wasn't physics as interesting as this when I was at school?, or maybe a better way to put it is, why were the physics teachers I had at school, so crap?
The "and then he calculated the frequency" bit is disappointing, frequency of what? How? How did they know when the light was passing through the gap but hitting a tooth? How did they know when light just hit the tooth outbound?
Should Jupiter have been rotated 90° down in your diagram to show that the movable moon (Io) you had displayed orbits Jupiter’s equator, and not from pole to pole (as depicted in your diagram).
Light has a different speed according to the environment.
Light speed is not a constant,
Gravity affect the speed of light,
Also oxygen particles affect it's speed
slowing it down,
We've only measured it here on earth affected by Gravity and gas molecules.
Out of space, in a perfect vacuum, without gravity, in one way direction, light travels much more faster because it has no barrier.
It also means that 14 billions light years away galaxies are been measured wrong, light does not take that long to reach us, we are receiving it's light much more faster, so the age of the universe are also being dated wrong.
Check out "Measuring the speed of light the old fashioned way: Replicating the Fizeau Apparatus" by AlphaPhoenix
We should have rounded up to exactly 300.000 km/s when we were at it. This would have changed the meter by a mere 1%, well within the rounding error of thumbs and feet🤣
Sometimes nothing make sense. Went to see photon matter interaction, i couldn't understand so many terms. It seemed interesting tho. Wikipedia pages are sometimes very confusing. Which book should i start with for quantum mechanics, any idea? I am familiar with basic quantum theory and calculus.
Didn't Galileo conduct a SOL experiment? It involved two distant observers each with covered lanterns. Galileo correctly realized that the finite human reaction time obscured any short or zero light delays
8:17 what "light source" is he shining 8.6km and back in 1851 to bounce off a mirror and still be fine enough to measure thru the tooth of a cog? Nothing adds up about the details of the Fizeau experiment.
The celestial and planetary experiments don't appear to factor in the movement of our solar system through space (~500k mph), or the motion of the stars either. With those factors taken into consideration, the actual distances involved would be different, greater or perhaps less, depending on the relative direction of travel.
Everything about this video makes perfect sense to this Texas guy except kilometers. The universe revolves around inches and miles. My woodworking ruler tells me so.
So the definition of the length of the meter now depends on the speed of light. And the speed of light depends on the length of the meter per definition. Why wasn't it possible to define the speed of light to 300,000 km/s?
The original definition of the meter was a percentage of the distance from an earth pole to the equator. I'm sure the historical measurements of that distance had a big error span that would allow a 300,000 km/s definition to stay consistent with old publications.
explanation of roemer and fizeau's methods are not just hand wavy but simply unclear. The Bradley explanation unintelligible. He kind of just about understands the material at a superficial level, so is therefore unable to articulate clearly.
The speed of light has NEVER been measured, just estimated. You literally cannot measure it because neither space nor time is constant and ni way to prove that space-time is constant. Similarly, there also is no empirical way to determine that the speed of light in a vacuum is constant. That is just an assumption that simplifies some theoretical physics equations, which are proving each day to be less reliable.
The really tragic story behind this, is that it is all wrong. It is incorrect knowledge, and it should be retracted with an apology. There would never ever be any delay in anything that Roemer observed, because he was looking through a telescope. This is not anything other than the beginning of a tale. Please take five, think, retract, and apologise for the error.
6:35 That explanation ist clearly wrong. The effect has nothing to do with the time it takes light to travel from the star to the earth. If it had, stars in different distances would have a massively different effect (since the distances of stars and galaxies differ easily by a factor 10^9).
Thr effect he saw is about the perceived change of direction due to earth's movement. Compare it with a car. If the car is at rest, the wind can come from the side. The faster you go, the more the wind seems to be coming from the front.
It is not clear how Roemer was measuring the periods of Io and determine it's about 45 hours.
Watch the addendum.
The speed of light is variable through the same material depending on time but not on place. The speed of light is not a constant. Discuss...
Great video. But what happens if it turns out that light travels at different speeds coming back from the mirror to that going towards the mirror? These measurements assume that the speed is constant in both directions, and measures the average speed!?
🤓 have you been watching Derek Muller’s video?
there's no real determined speed of light because there's no one way speed of light because in some directions it could travel faster than others. Say for example you were on mars and you were trying to adjust your time to that of the earth, and normally with the one way speed of light it could be possible that it takes 10 minutes to travel to mars and back so to say, you get a message that says "this message was sent at 12:00" then u would be able to say that the one way speed of light took ten minutes to travel to you and set the time to 12:10 and say "this message was sent at 12:10" and noone will have an issue cause they assume it took ten minutes for the one way speed of light to reach you. But there's a problem. Noone knows how the speed of light travelled, so it could be that the speed of light had travelled 20 minutes to reach you but you wouldn't know because you can't time it, so the speed of light could've taken 20 minutes to reach you but to go back to the earth it could be instantanious, but since noone was monitoring it and you don't know the time you would just assume itwas 12:10 with the one way speed of light.
jUST CONTENT!!!! nO ADS??? I have GOT to support you good sir.!!
This is foolish thing, because when earth is far, then the light will also come late to earth, why are you not able to understant small thing, so there is no difrence betveen elicpse interval. Speed of light is infinite but just looses its way after some distance according to size of object.
2:33 Hi, Please if you have a minute: why around H, Jupiter would get in the way? Doesn't its natural satellite end up on one side or the other of the orbit where it is visible again?
Has anybody worked out the measurement of the speed of light in a one-way test as opposed to halving the results of out and back measurements?
thanks -> to all those people
This was extremely interesting... high school science should also include the brilliant ways our ancestors made their discoveries
There is the chapter in 10 standard ncert book . If you study you will know .😅
God.....still boy you don't get enough from Newton's apple????😮😮
Dats fuckn awesome
Keep thinking if redoing Foucoult's method. Just to do it myself. One day...
What software is being used here? It looks like all of those are object you drag with your mouse and not just animations.
Stay tunes. Why put a break in an otherwise good video? Is it because professions do it that way and you are a mimic?
When my Mrs has a go at me I can easy break the speed of light getting down the pub! Love her to pieces but just sometimes I need a pint!
I love ur white coat
Is it 300,00 km/sec?
They set it going and after that no one could catch up to it to turn it down. Always been that way, and forever will be.
I kinda understand and get how mechanical waves move forward but how does light or any electromagnetic wave move? Or what does make it move and with that kind of velocity? All from that I’m just blown away with this universe🤯
WOW
It moves because a change in the electric field causes a change in the magnetic field, that change in the magnetic field then causes a change in the electric field and so on. The rate of change of of the electric field is determined by the universal constant the permittivity of free space, and the rate of change of the magnetic field is determined by the universal constant the permeability of free space, together they determine the speed at which light travels. No one knows why free space has these values, it just does.
Has anyone measured the 1 way TOF for light? Also, how does relativity play into it and... in the 2 way TOF, is the return speed the same as the send speed? Essentially , how do we Actually know if the speed remains constant between send and return?
They don't know. All their physics and theories fall apart unless light speed is constant. Which it isn't.
The celestial and planetary experiments don't appear to factor in the movement of our solar system through space (~500k mph), or the motion of the stars either. With those factors taken into consideration, the distances would be greater.
I fail to understand the Romos experiment. Even if Earth is farther from the Jupiter on Positions K and F as compared to G and L, the measurement of the periods on the moon must remain unaffected.
Have you seen the errata?
i call it bulshit, there is no speed of light. in order for something to have speed it has to be a physical object, imaginary objects can't have speed in reality.
Sound's not a physical object but it has speed.
@@phillipfubar8869 wrong it has no speed. sound is perturbation of medium just like lite
@@kestutisnikolajevas9870 Sound & light travel. They go from point A to point B. To say they have no speed is one of the dumbest things I've heard.
@@phillipfubar8869 contrary to your belief it does not trave. bullet can travel, your car or you can trave sound or light can't trave because they are not physical objects. hanse no light particle or sound particle being created to travel in the first place. it's simply field perturbation of a medium.
@@kestutisnikolajevas9870 So according to you, waves don't travel across water because they're perturbations of a medium?
Ding, cuckoo! Ding, cuckoo!
Christian Huygens was a brilliant guy, sadly even in the Netherlands he is underestimated
As a fellow Dutchman, I agree
Fizeau s cogwheel not drawn in 3d perspective may confuse student, as i was at 1st
300,000 km/s?
I believe it travels at 186,282 Miles per Second!
Is that so. Same thing.
ALLAH has mentioned the actual calculation of the speed of light in Quran
The only think is , they make a mistake couple of miles, so all the next mathematics are completely wrong
Could have just asked the girl from Planet Claire to check her speedometer. 😆
Good video but, how can it be proved that, over the vast distances of the universe, that light does not slow down?
If you say thet light moving in difference speeds true mettars, is it not make sence thet the numbers thet they meter in the begining is correct ?
Curiously, if you take the speed of light at 299,792,458 m/s and perform gematria on the number triplets the result equals 1. 2+9+9=20, 2+0=2. 7+9+2=18, 1+8=9. 4+5+8=17, 1+7=8. 2+9+8=19, 1+9=10, 1+0=1. If we perform gematria on the whole number the result is magic number 9. Add 9 for the whole number and 1 for the triplets and we get 10 which adds back to one. Don't know what any of this means but there is music in that number.
That's meaningless.
What’s the one way speed of light? It’s always measured in a return trip.
This is fascinating. Have no idea if all is true or accurate...but really curious who is giving this a thumbs down...but more importantly...why?
Is the info not good? Do they not like this guy? His presentation? What?
I've never thought of this question before...but find this a great place for me to start.
thanks for the support
How does different positions of earths orbit produce different periods for io? Although light takes longer to travel, this will just delay when we first see the moon (start of period) and when it finishes its orbit (end of period). But won’t the duration of the period itself remain constant ?
Erick + You are right. A lot of YT videos give the same reasoning that this one, but there are videos where they give the correct reasoning. As the Earth and Jupiter move in their orbits there are periods when the distance between them becomes smaller, they are closing to each other, and there are periods where the distance becomes larger and larger. In both situations you see Io starts an eclipse and measures the time when it is visible again. In the first situation the light had to travel a shorter distance that in the second situation, so the eclipse is "shorter" than when the planets are moving away each other. So the important factor is the relative movement between Earth and Jupiter.
@@josenriqueha right yea this does make sense. Thank you
@@erickrajan7401 You're welcome. HighSchoolPhysicsExplained gives this explanation in the link that appears at the end of this one.
More rigorous explanation of James Bradley experiment would be appreciated. Everything with thorough details of wave vector directions, animated diagrams of stars, earth movement.
I know it is hard work to be thorough with this )). Maybe someone has already done it?
The universal constants are not really constant ? Speed of Light is one of them
The speed of light has no history.... it's always been there.... ;-P