history of the speed of light and how its speed was determined

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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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Using a microwave to determine lightspeed - • Determining the speed ...
Why the speed of light is precisely 299 792 458 m/s - • why is the speed of li...
Maxwell who determined light was an electromagnetic wave - • Maxwell's Equations An...
Michelson and Morley's null result at detecting Aether - • michelson morley exper...
An Intro to Special Relativity which relies on the constancy of the speed of light - • Einstein and the clock...
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Опубликовано:

18 апр 2019

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Комментарии : 540

@Squishergeo 4 года назад

Just a note to say thank you! This was a great video. Have subscribed. Keep up the excellent work!.

@PhysicsHigh 4 года назад

Thanks Daniel

@AbhayKumar-um8vl 3 года назад

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.

@kennethmacleod5926 3 года назад

@@PhysicsHigh llllllĺĺllllĺllllll2

@archimedesmaid3602 10 месяцев назад

@@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%

@alexandrekassiantchouk1632 2 месяца назад

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.

@IngmarSweep 4 года назад

Thanks for not disturbing your interesting story with background music.

@primemagi 2 года назад

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

@jimlassiter749 11 месяцев назад

Amen...!

@MrSorbias 11 месяцев назад

@@primemagithat's not why we do it tho 😅 The music is added to combine it all together and hide for example background noise.

@keithtomey5046 11 месяцев назад

@@MrSorbiasIt makes videos impossible to endure - such a shame when the content is otherwise good. (Dot)

@savage22bolt32 10 месяцев назад

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.

@xaplomian7294 3 года назад

Timestamps for each speed of light experiment Ole Romer 1:04 James Bradly 5:12 Hippolyte Fizeau 7:53 Leon Focault 12:15

@dalitnahipehlehinduhu6569 2 года назад

Vedas said first

@mobashwerabegummrs.7857 Год назад

Thanks

@lucvl4557 11 месяцев назад

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.

@TiniDarer 5 лет назад

This is amazing! This video definitely deserves more views! Thank you.

@robertgoss4842 4 года назад

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!

@PhysicsHigh 4 года назад

That’s great feedback. Thanks. I do hope you share.

@josepacheco4093 4 года назад

Good job. Very nice explanations. You provide the right insight without going into much detail.

@morley7584 4 года назад

This video deserves more attention. You guys really helped me with my uni report on thr measurment of light speed

@beenaplumber8379 11 месяцев назад

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.)

@ptgr12 8 месяцев назад

It’s all incorrect knowledge, and should be retracted. Roemer would never witness a delay in anything, because he was using a telescope.

@beenaplumber8379 7 месяцев назад

@@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.

@ptgr12 7 месяцев назад

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.

@ptgr12 7 месяцев назад

@@beenaplumber8379 I am right. 100%, and all it takes is a little common sense, which is something lacking everywhere. Obviously.

@beenaplumber8379 7 месяцев назад

@@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?

@marksimpson2321 10 месяцев назад

A fabulously clear explanation of how Roemer calculated the speed of light! Worth it for that alone! Ty

@robertsynclair9046 4 года назад

excellent video, thank you for investing your time and effort on this. I am sure that with time this will become a very popular channel.

@PhysicsHigh 4 года назад

Thanks. Hope so

@user-vk3sf2qp4d 11 месяцев назад

Excellent! A bit closer to understanding the speed of light! Thank you!. Absolutely fantastic! Thank you so much. Keep them coming..

@AlexThompson171 5 лет назад

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)

@PhysicsHigh 5 лет назад

Thanks Alex. I stand corrected.

@avnertishby 4 года назад

@@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.

@PhysicsHigh 4 года назад

...and I am working on a fix.

@PhysicsHigh 4 года назад

Here is my correction: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-TAIlswch5d0.html

@justinclark3199 Год назад

THANK YOU SO MUCH I WAS SO CONFUSED AS TO HOW HIS EXPLANATION WOULD HAVE WORKED

@dqvissmyph2968 11 месяцев назад

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!

@randallblake1213 10 месяцев назад

Excellent video. Subscribed!

@mpolier 11 месяцев назад

Excellent! A bit closer to understanding the speed of light! Thank you!

4 года назад

Good watch after videos about the Maxwell's equations and his realisation that light is but an electromagnetic wave.

@thalesnemo2841 4 года назад

Excellent video! Clear and concise.

@robertgoss4842 2 года назад

Excellent! A fine blend of mathematics and ordinary human language. Well done! I quickly subsccribed.

@dwtalley 11 месяцев назад

Wow. At age 65, I am suddenly a high school student studying a subject that teenaged-me dismissed as boring. Thanks for that!

@profdc9501 4 года назад

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.

@bpolat 2 года назад

Wonderful content. Thank you very much for great video.

@BobtheScienceGuy 5 лет назад

very nice video, I've been getting questions about this and may adapt it for my channel.

@WitchingNumbers 10 месяцев назад

It's appreciated that this is a history/basic concept video , yet an introduction to the measurement being relative to Earth normal space with time dilation would be appropriate.

@philo5923 3 года назад

Absolutely fantastic! Thank you so much. Keep them coming.

@PhysicsHigh 3 года назад

Thank you! Will do!

@simranjoharle4220 4 года назад

This was an amazing video....thank you sir!

@tanishashiuli8037 3 года назад

Wow!!really so much informative☺

@pushkarranade 3 года назад

Nicely done 👍🏻

@DutchZippy 4 года назад

Excellent video, a difficult concept explained really well.

@PhysicsHigh 4 года назад

Glad it was helpful!

@archimedesspiral 4 года назад

Good explanation and genius experimenter

@ninalehman9054 10 месяцев назад

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.

@CandyCodedBasix 3 года назад

Amazing video. Thank you for this.

@PhysicsHigh 3 года назад

Glad you enjoyed it!

@GerardHammond 11 месяцев назад

Wonderful. Subscribed immediately

@PhysicsHigh 10 месяцев назад

Awesome, thank you!

@olegyamleq7796 3 года назад

WOWWWWWW!!!!!!!! This was brilliant !!!!!!!!!!! Thank you. Excellent explanation !!!!!!!!!!!!!!!

@PhysicsHigh 3 года назад

Thanks!!!!

@jeffrogers210 11 месяцев назад

Excellent! Thanks!

@marksmith1960 2 года назад

Seriously though excellent lecture.

@mr.e7379 3 месяца назад

jUST CONTENT!!!! nO ADS??? I have GOT to support you good sir.!!

@jlpsinde 4 года назад

Amazing video, thanks.

@PhysicsHigh 4 года назад

Thanks for your comment

@samk6042 5 лет назад

Thanks sir! Will u be releasing more videos for physics hsc syllabus module 7? Really wish u were my physics teacher at school!!

@PhysicsHigh 5 лет назад

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

@spiralsun1 11 месяцев назад

Awesome ❤thanks!

@BBQDad463 4 года назад

Thank you for this excellent presentation of the history of the speed of light.

@PhysicsHigh 4 года назад

You’re welcome. Please do share

@syb36 3 года назад

I missed Morley!

@noxnc 4 года назад

Great video, thank you.

@jeffreystarnes9500 3 года назад

Excellent!!!

@astrospeedcuber 2 года назад

This is an amazing channel

@PhysicsHigh 2 года назад

Thanks

@jeliasc 4 года назад

Great video

@damienbull8160 3 года назад

When I watch this program I understand the great minds and brain power that these individuals possess. These are truly remarkable individuals and they were working from the foundation that was laying down thousands and thousands of years ago by their ancestors. And when I say Foundation I mean genetically.

@jamesbarringer2737 2 месяца назад

This is brilliant.

@JustsomeSteve 2 года назад

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!

@ripsumrall8018 4 года назад

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!

@daleeasternbrat816 3 года назад

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.

@ripsumrall8018 3 года назад

@@daleeasternbrat816 I know that!

@davez4285 2 года назад

Excellent video, thank you! I have a question : James’ method demonstrates the speed of light is relative to earth’s motion. If every two years or two turns, the angle will be twice. If the reference frame is on earth, the light speed c, will be a function of the speed of earth. Why we think the speed of the light is considered as constant regardless of reference frame?

@okaro6595 11 месяцев назад

The speed of light is same relative to all observers. Of course he could not know it.

@daved3494 4 года назад

Excellent overview of the early days of establishing the value of C. Really well done.

@PhysicsHigh 4 года назад

Thank you Dave

@jakekp4739 5 лет назад

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

@vtbn53 4 года назад

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.

@howardcallahan6692 4 года назад

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.

@PhysicsHigh 4 года назад

thanks Howard, you are correct and my error, I am working on a fix

@PhysicsHigh 4 года назад

Here is my correction: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-TAIlswch5d0.html

@user-ky5dy5hl4d Год назад

@@PhysicsHigh I think you have a mistake in the video. At 14:54 min., you have 299,792,472 km/s. I think it should be meters/second not kilometers per second.

@johnaugsburger6192 3 года назад

Thanks so much

@ramadash2472 4 года назад

really good information which is not available at text books👌

@vihanroy2842 4 года назад

Hi sir. For this dot point in our syllabus, how much maths do we need to know? Or do we just need to understand the concept? I will wait for you reply Thanks Sir

@PhysicsHigh 4 года назад

I am not the exam committee so I can’t guarantee everything but my decades experience tells me, no you’re very unlikely to get a maths question on this this outcome (we don’t refers to them as dot points anymore). What I would say is that you should be familiar with a number of historical examples of light speed determination. Also you should be able to discuss how science works - the prediction of light as a wave with a finite speed and the experiments that validate that model, and how each experiment, with increasing precision leads to increasing accuracy. Note how I use the terms. Hope that clarifies. You ask a good question that deserves a longer answer.

@professorParsley 4 года назад

indeed superb!

@webjammer1 4 года назад

A simple way to test the speed of light is to try and open the refrigerator door before the light comes on.

@rudolphguarnacci197 4 года назад

It's actually faster because it's cooled. And everyone knows light travels faster in a vacuum cleaner and a refrigerator.

@stefanc4520 Год назад

So if I open my fridge I could somehow deduce the exact speed of light? Lol

@OmniGuy 11 месяцев назад

Or hit the light switch and be in bed before it gets dark.

@ColinWatters 11 месяцев назад

Get through the road junction before you see the red light.

@mariorqmsilveira3270 Год назад

14:54:..... this align so much with the speed of light (events) that Maxwell could state light was a form o electromagnetic wave! To me, in this resides the greatness of this video! Thanks!!

@jpapan1 3 года назад

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.

@PhysicsHigh 3 года назад

thanks for the support

@josenriqueha 4 года назад

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.

@adrianpjones 10 месяцев назад

Exactly right

@adrianpjones 10 месяцев назад

Such a fundamental mistake seriously reduces the credibility of the video.

@myherpesitch7763 4 года назад

Love your accent Love your teachings

@PhysicsHigh 4 года назад

Thanks

@studypurpose7804 Год назад

Good!

@sandmonke21 4 года назад

Damn. This really is good, physics is one of the most interesting things in life.

@acmefixer1 4 года назад

@Creed Follower **Physics is everything**

@sandmonke21 4 года назад

@@acmefixer1 pure facts

@kimmariager3420 4 года назад

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.

@behnamashjari3003 3 года назад

Great video. More than high school level.

@outlawzgosu Год назад

What software is being used here? It looks like all of those are object you drag with your mouse and not just animations.

@MegaLokopo 11 месяцев назад

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?

@godsrighteousness5003 4 года назад

great video

@PhysicsHigh 4 года назад

Thanks

@zitscx886 2 года назад

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.

@nugget4life420 Год назад

Our teacher loves to use your videos

@fa6805 4 года назад

Suggestion. Please put captions. It was kinda hard to hear the names of the scientist you mentioned.

@hariprasadreddy108 4 года назад

Its simple ele vara#$&*"&eee

@PhysicsHigh 4 года назад

Captions are available - you just click the caption icon

@janedoe5229 3 года назад

click the little "cc" button in the lower right of the video screen.

@acmefixer1 4 года назад

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.

@colt4667 2 года назад

The tube (a pipe) was pumped down to a vacuum. Does it still exist?

@ProProboscis Год назад

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?

@b0101001110 3 года назад

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 ?

@njodzenyuyadamubatinyuy6075 3 года назад

Need to know more please

@johnbrock1602 4 года назад

Could you say something about the speed of light experience done on top of Mt Wilson? Thank you

@PhysicsHigh 4 года назад

Interesting you should ask that. My next video released this Friday will touch on Michelson experiment though not in great detail. I focus on his final experiment in 1931 but uses pretty much the same “time of flight” method.

@greggweber9967 Год назад

About a year ago, I saw a RU-vid video saying that because of the new way of measuring the Speed of Light, we wouldn't know if it changed. Can we detect any change?

@lambda4931 4 года назад

The angle of the reflection needs to be divided by 2. If a mirror rotates 5 degrees the mirror’s reflection will move 10 degrees.

@meibing4912 4 года назад

Did the Fizeau experiment in High School Physics. Could drive you crazy setting it up right. A sneeze and it was ruined.

@PhysicsHigh 4 года назад

that would be a challenge. Did you get a credible result?

@meibing4912 4 года назад

@@PhysicsHigh not really. It was too difficult to get a stable setup. I'd call the results very "biased" towards merciful interpretation of the facts.

@JDrwal2 4 года назад

Great educational video. But I watch 5 such videos a day, so how can I support all of them? There is something wrong with the system or with the expectations.

@PhysicsHigh 4 года назад

Thanks for the feedback. 5 a day huh. Must love physics then 😀

@wplg 3 года назад

Light-Speed is measured by the around trip a+b=c. Take away "a" light speed speed will change.

@BadPennyDogBoy 3 года назад

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!?

@PhysicsHigh 3 года назад

🤓 have you been watching Derek Muller’s video?

@davidkleinthefamousp 3 года назад

I got the star measurement method. Cog? not a clue. Do they use a stopwatch?

@MrBeen992 4 года назад

Very good

@PhysicsHigh 4 года назад

Thanks

@johnaugsburger6192 3 года назад

Thanks

@JoeBlowUK 11 месяцев назад

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.

@christobotha5378 4 года назад

Major issue I have with topic. Does the light travel that fast or is it the speed of illumination that travels that fast. Light must have a certain value of power, strength or intensity. Does this mean the speed of light is variable, but the speed of illumination is the same. Speed of lght using planets is not scientific. Is the universe not expanding? How do they have exact distance to planets?

@rushilpatel7418 2 года назад

This was extremely interesting... high school science should also include the brilliant ways our ancestors made their discoveries

@tanishmalik9807 2 года назад

There is the chapter in 10 standard ncert book . If you study you will know .😅

@basudevsamantaray2363 Год назад

God.....still boy you don't get enough from Newton's apple????😮😮

@2869may 2 года назад

How did Fizeau set up a 4,315 meter experiment? what was the light source? what produced the constant rotation of the cog?

@colt4667 2 года назад

Good questions, Nick. And how were the revs per second of the wheel measured with accuracy?

@2869may 2 года назад

@@colt4667 Right, What kind of time instrument could record a speed of 186,000 per second at a distance of 8,630 meters...? That would be in the 1,000ths of a second a if not 10,000ths or 100,000ths.... I don't believe anything...! LOL

@bobhoward6750 Месяц назад

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.

@burntsider8457 4 года назад

Interesting topic well presented. Refreshing to view a STEM video without puerile inanity.

@petefluffy7420 11 месяцев назад

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.

@erickrajan7401 4 года назад

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 ?

@josenriqueha 4 года назад

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.

@erickrajan7401 4 года назад

@@josenriqueha right yea this does make sense. Thank you

@josenriqueha 4 года назад

@@erickrajan7401 You're welcome. HighSchoolPhysicsExplained gives this explanation in the link that appears at the end of this one.

@ibmlenovo1 3 года назад

This by itself is a serious question that, which or what clock were these scientists using at the time of experiment.

@andywander 11 месяцев назад

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?

@adrianpjones 10 месяцев назад

Exactly right

@PhysicsHigh 10 месяцев назад

Did you see my errata?

@IBITZEE 4 года назад

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?

@PhysicsHigh 4 года назад

c stands for celeritas, which means swift in Latin .

@GeorgeSPAMTindle 4 года назад

@@PhysicsHigh Which is also where we get 'acceleration' from, it means an increase in swiftness.

@GeorgeSPAMTindle 4 года назад

@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'.

@Whiteyy191 2 года назад

I have a couple of questions: how did fizeau determine the rotating speed of his wheel and how did he maintain a constant speed without an electric motor?

@2869may 2 года назад

It's all Bullsh!t....!

@2869may 2 года назад

And what was use as a source of light at that time....?

@backnineblues5843 4 года назад

There were so many brilliant scientists who toiled in relative obscurity. Of course Maxwell was famous but I had never heard of these other gentlemen.