Einsteins Theory of Special Relativity in 2 minutes

[skeight976]

how can we humans judge the speed of light? when we can only see a fraction of the actual spectrum of light.

[MrSharan1997]

/watch?v=Qg4nWT3FYJI

[marcos13af]

The light can not travel in diagonal path referent to the source,since then,the light speed is constant(in this case),light will take the same amount of time to reach each mirror,no matter how fast it(this sort of light clock,or whatever)travels...for both observers...

[thegodofevil]

I wish you were my physics teacher so bad!!!! =,(

[sikpikfrank]

I appreciate your very nice graphic explanation. Keep up the good work sir!

[sizzlerjoe1]

He's wrong, with the observer b on the train, they are only looking forward to see the one lightning strike, they would not see the other at all...

[okandjo]

well made ;)

[saedt]

ooh i get it!

[nickharvey7]

@99thmonkee Einstein also said “for us physicists the distinction between past, present and future is only an illusion”. Maybe a good education would help everyone!

[nickharvey7]

Very good video!! I am very interested in physics but I am only an amateur

[SuperMagnetizer]

Sorry, Herr Einstein, but you're wrong. (BTW, what happened to your German accent? I think you're an imposter!) What would observer B inside the train see if two tiny flasks of gunpowder exploded the instant that end of the train got struck? The answer is that she would see simultaneous strikes just like observer A. But she would still record non-simultaneous bolts of lightning outside the train. The lightning strikes were simultaneous, in universal time.

[DomhnallX50]

ur talking about newtonian time which states tht time is the same everywhere which is not true according to general relativity

[92rachh]

you're correct, but this works because the gunpowder flasks are within the train-traveller's inertial frame of reference, whilst the lightning bolts are not: thus you are comparing two different phenomena. good point, though :)

[SuperMagnetizer]

Thanks, 92rachh. I finally found a fellow thinker! . :) :) :)

[SuperMagnetizer]

An "event" happens at a specific point in space and in time. Each observer is located equidistant spatially and temporally within their own frame, from the two events. While the man outside the train isn't moving relative to the two events, the woman inside is moving spatially toward the forward lightning strike event and moving away from the rear strike, explaining her seeing the front one before the rear one.

[robertbright777]

The question is did the lightening strike at exactly the same time? If so the answer is, observer A is correct. Reason: Just because observer B see's the lightening strike in the front first does not mean that it actually struck first. The light just traveled to her first.

[ABE4217]

@robertbright777 Your so right. I love the way you put it!

[IcarusFlying]

best explanation yet :D thanks

[SoNotClever]

Patrick Bateman at 0:24? Or does he look like someone else from where you're sitting?

[kebabsallad]

This is dern interesting. !

[harmonicgrunt]

U thick Chav Jock.

[DerekG8383]

at 0:45 you made a mistake. You said that the light travels different distances and that is why the train observer B sees the lightning at different times. However, the light only travels different distances from the perspective of the OUTSIDE OBSERVER. From the frame of reference of the person inside the train, the light traveled an EQUAL distance from his frame of reference because he is in the middle of the train. THAT is the whole point of relativity.

[harmonicgrunt]

I have sent this video out ~~ Global >

This guy said he has seen the Lock-Ness Monster..as Well...LOL.

this guy is a JOKE> RETARD.

[trtnec]

@DerekG8383 no, actually the video is right, if the outside observer sees two strikes simultaneously, that means the train perspective does not see them simultaneously. Conversely, if the train perspective sees them simultaneously then the outside observer does not. People, stop thumbing up comments that are wrong! You guys are confusing the light bulb thought experiment, they are different, the light bulb experiment describes the latter situation (simultaneous event inside train).

[sprucegoose429]

Im confused. If the speed of light is constant for all observers, why does the observer on the train see the two lights at different times? In the animation, it seems as though the person is observing the speed of light to be slower when it comes from the left, but i know this can't be true. Can someone please explain?

[futurez12]

The speed of the light itself isn't changing, it's the observers point of reference that is.

The passenger on the train is moving towards the light at the front, and away from the light at the back, basically cutting down the distance the light needs to travel from the front of the train, and increasing the distance the light travels from the back. Where both beams of light are travelling at the same speed, the one travelling the shorter distance will hit your eyes first. hope that helps :)

[newyork471]

When the lightning strikes both ends of the train, the light moves towards observer b, and observer b moves towards the lightning too, since she is on the train. This means that the distance is shorter, meaning it will take LESS time for the light to get from the lightning striking point to Observer B. The fact that the speed of light always moves at the same speed has nothing to do with it. If you always move at 15mph, 1 mile to travel will take less than 2 miles to trave.

[deronryan]

It's not that it's slower, it's that the observer in the train is moving away from the approaching light on the left.

[whatthehellisaplough]

The speed is the same, the distance isnt. If you were walking towards your friend at 0.5mph, and he was doing the same towards you, It would take less time to reach eachother than if it were only you walking. It would take twice as long in that situation. Now the light that relected off the front of the train, becase he was moving towards it, took less time to reach him than the light at the back of the train, which he was moving away from. Since this light reached him first, he saw it first.

[Trivialnights]

JamesMorlan is right. You have to fix your video at 1:45.

Its the other way around. I know because I have a test in 2 days from now and I'm studying hard to pass that damn physics test.

Correct answer is:

For observer B: a short amount of time like hours

could be

For observer A: a looong period of time. Years to be exact.

[EH3Films]

I could fix it, but the debate is far more interesting, plus it was for a college course in TV production which i've managed to pass... good luck with the test ;)

[Trivialnights]

oh nice.

I actually appreciate your video a lot. Its helped me UNDERSTAND this theory a whole lot better.

Unlike the other ones -_-

which I won't name...

- Thanks for the good luck :D

[christiangoth84]

I would suggest that fixing it is important because otherwise it is likely to misinform some individuals who do not read the comments.

[fuckgodfuckyou]

Errr......your the one thats wrong!!

Observer A is the pilot...

Observer B is the land observer....

1 year for observer A could be 10 years for B, NOT the other way around!!

[conspirator272727]

Exactly. Hasn't anyone seen Planet of the Apes?

[kapplejacks22]

I would like to know are dreams another dimension? Sometimes in my sleep I feel like i'm on some adventrue for hours and hours, but when I wake up I realize I've only been sleeping for about 20 minutes. If dreams are another dimension, It could be used to explain the relativaty theory. Makes sense?

[overacid]

thanks for that

[JamesMorlan]

You mean to say, the closer you get to the speed of light, the SLOWER time passes. It's the person traveling near the speed of light that will see only one year vs. ten years for the guy on the space station.

[danielelteso]

lol...soccer is not easy..lol

[Asdam12]

Every video I watch, I learn a bit more about relativity!

Thanks for uploading!

[HaleyDCullen]

Learned a bit! THanks!

[danielelteso]

or...lets say ur playing soccer...two people at the same distance from u and on opposite sides throw a ball to you at the same speed

P1 YOU P2...

if u run towards P2, the ball that was launched from there will hit u in the face sonner because ur aproaching it...and ur running away from the ball from P1

[damnation2424]

EXACTLY!!

man u are just inspiring.

[atsporty]

man you must have taken a lot of balls on your face

[danielelteso]

ok..lets picture the girl part this way..lets say ur on a boat at 50 kph, and u go on another at 30kph...both go on opposite directions. At a defined distance, they move towards each other...since they both approach each other, they will meet sooner than if one stays still and is the other approaches

because the girl is ON the train she moves at the speed of the train towards the right side all the time.if something approaches FROM THE RIGHT, it will meet her sonner than something from the left

[Lsrpwer13579]

so, bacically if your going 299,792,458 mps, a light beam will pass you as if ur not even moving.you'd think since your going 299,792,458 mps (the speed of light), that you'd keep up with the end of the light beam and you could look beside you and see the end of it.but no, it somehow still passes you as if your not moving and its going the speed of light.Soo, for a person that REALLY isnt moving, would the light be going 2 times the speed of light?No.special reletivity is just weird.

[ubcphysicsyangbo]

S.R isn't weird; it's only weird because our common sense intuition of reality is dead WRONG

[Lsrpwer13579]

your right. sorry. its actuilly our thinking that is weird, even though its hard to think that way.

[Zanteogo]

One has to remember movement is only relevant to other objects. There is no "universal set point" to gage ones speed. Because of this frame of reference is what is "real" to any observers within that frame of reference.

This also means that to anyone it appears that rest of the universe is moving AROUND THEM and they are standing still.

Also, the speed of light appears to move at the same speed regardless of movement Even if one is moving away OR towards it, it still comes at the same speed.

[Zanteogo]

Cont...

Because of this, both flashes should reach the moving person at the same time.

I have seen this thought experiment shown several times and to me it seems wrong. I have yet to see a valid reason based our understanding of relativity why both flashes would not be seen at the same time.

I don't claim to be an expert, so there is a good chance I am wrong. I just have yet to see a good explanation as to why I would be wrong.

[vic47haden]

@Zanteogo

I agree that this train example which is often given is incorrect. The man on the track's perception would be that the girl would see the front strike first and the back last. That perception would be incorrect because of how light acts. Time and space would alter to allow the girl to see the strikes at the same time.

If the example is correct then a person travelling on a train going in the opposite direction would experience the strikes in reverse order. Surely that cant be right

[rickybirch]

This is impossible! Einstein once said that

if you hold a mirror and move forward with a

speed of light you could never see you on the

mirror! So how can second flash reach you if

you are movin forward with a speed of light?

And even if you see it after the second

one it would be because the second one needs

more time to reach you! An observer can see

both flashes cause he is not moving, so

everything is normall here.

[bozcro4lyf]

It is not possible for somthing with mass to travel at the speed of light. Thats why we use terms such as, half the speed of light. Remember its not possible to travel at the speed of light but it is possible to traval half it.

[54spiritedwill54]

pretty good i liked it sums it all up pretty much nothing really you left out or was in excess :)

[gbushisfun]

can you tell me why it takes longer for the longer path? so when you throw are seated in a moving plane and throw something down it takes longer to hit the floor than if you would not be in a moving plane? thats kinda weird

[SeanyFuckingG]

If you dropped something when you where in a plane, you would be moving the same speed as the plane when you dropped it, so to you, it would go vertical.If you cut the plane in half and allowed someone to see you drop something as you went past in the plane, say that person drew a line to show the path of the object, for him, that line would be slighty horizontal.

[SeanyFuckingG]

Draw a vertical line on a bit of paper(the path of a falling object), continuesly going up and down over the same line, then slide the paper to one side whilst doing this(the movement of a moving plane from the perspective of a stationary person), the line will no longer be vertical, even though you were drawing a vertical line. Because your perspective is different relative to the bit of paper.

[lamrof]

Fine, there will be a horizontal aspect in ball dropped or the line you are drawing, however why is it observed to be taking longer to bounce back up from the perspective of the external and stationary observer?

[kciNJNadon]

I believe you first example is wrong. Both observers would see both sources of light at the exact same time. Otherwise, you render the statement "Light is constant" obsolete. But the statement is not obsolete.

Example: You are running at 15km/h away from a friend. A friend turns a flashlight on at you (to your back). You expect the light to seem to travel at "c" -15km/h. This is not the case. Because light is constant, it will always remain at the speed of light.

[fartingabyss]

i think you misunderstood the video. The girl in the train would not see both lightning bolts at the same time, since light is constant, and by that meaning its velocity is always constant, then since the train was moving towards the lightning on the right it would see the right one first since both lighning bolts are travelling at the same speed, but not the same distance. :D

[Zanteogo]

I must admit I don't understand this either. Light is supposed to move at the same speed for all observers, no matter what speed they are moving at or the speed of the light source.

If this is true, the speed of the train should no effect the time the light takes to reach her. From her frame of reference she is not moving, the world around her is in fact moving. This would mean the light would reach her at the same time.

[bozcro4lyf]

Yes it is constant. That is why the girl in the train sees the front one stike 1st. To see both lightning strikes at the same time the speed of light at the back of the train would have to be faster than the speed of light itself, but as we know this is not possible. So if the speed of light dosent change something must. And that something is time.

[Zanteogo]

Yes, but if this where true light moving opposite to the movement of our galatic cluster would take longer to reach destinations versus light not, even if it started ON earth. (Or one could use the speed of our solar system moving around our galaxy)

Being as our galatic cluster is moving pretty fast it would be a measurable effect. Unless I am missing something it has never been noted.

[Telepcanin]

great, much better than In my fucking school where they just tell u some fucking definision and u have to me smart as albert to figure it out,

[Vorkagen]

Good good, but you should fix the sound on it.

[getteshome]

very helpful thanks

[zsam22]

Fantastic! Very succinct. You made your point without any mumbo jumbo. thankx ;0)

[eddiefonzarelli]

great video, hope you got an A mate.

[squirrelsivertsen]

soo does this mean if your travelling at half the speed of light & are looking at a star 10 light years away from earth.

You are seeing the star 6.66 light years away?

Because Your seeing light travel the speed of light + the speed your travelling at.

(300,000KM a second = 150,000KM a second)

Soo the star instead of being 10 light years away, it's 6.66 light years away.

Because 300,000 is two thirds of 450,000.

(10 x 0.66)

[reksub10]

i dont think so bcos a light year is a distance not a speed

[perltech]

Wow, Great way to explain it.

[obtainTR]

how can she see this if she's staring in one dierection she cant possibly see both the back and front at the same time

[lamrof]

Hahahaha, right. Smart people ask questions children ask.

[emperorles]

Would it be possible to let me know the name of the song that is playing in the background of this video? I really like it. Thanks.

[EH3Films]

Hi, the songs Natureland by Amon Tobin. Enjoy!

[GaryKoji]

Very much appreciated, I am trying to make a vid that explains the math. This is one of the best I've seen explaining the reason for the space time distortion, which I was struggling to understand properly.

Cheeers!

[ryan1111111555555555]

if you could generate i spiralled beam of light you can send stuff back in time!!, lol we have come very far as species, Einstein would be very proud

[arkmhed]

Please regard that Einstein was also an open advocate for peace and social justice. Could you confidently state that a man of his convictions be 'proud' of a world plagued by social unrest and vilification of many minorities?

[ryan1111111555555555]

no deffinately he understood where the world was going and even stated,

''WW4 will be fought with sticks and stones''

however no one can deny that our advances in technology are something to be proud of, even though it is being used for darker purposes

[spikeymidget]

Cheers Mike I hadn't realized that you had put this up... now the whole world can gaze in bewilderment at that sinful collection of hairs beneath my nostrils.

WORLD KNOW MY SHAME!!!!!!!

[thehatchninja]

"...the same is true if you run toward oncoming photons {light), or if you chase after them - their speed of approach or recession is completely unchanged, the still appear to travel at 670 million mph."

Quotes taken from The Elegant Universe, by Brian Greene. P. 31 and 32

[EH3Films]

thanks for commenting, agree with your point. there are a few points in the film that are'nt exactly on the mark but the 2 min maximum limited what i could explain, glad you liked how it was put together though :)

[thehatchninja]

That's a very well put together video. Unfortunately it's incorrect. Observers A and B would both observe simultaneous lightning bolts.

"Almost a century of effort by a series of dedicated experimental physicists has shown that any and all observers will agree that light travels at 670 million mph, regardless of benchmarks for comparison."

[ryan1111111555555555]

so your sayin the thory of relativity is incorrect????

[sebi123654]

YES THE light travels the same only the point of view changes so the light has a shorther distand 2 travel 2 point B than A so it reaches point B fastr than A kas point B is closer

[Zanteogo]

I have to agree with thehatchninja.

From the "moving" observers frame of reference everything else is moving and THEY are standing still.

Light apears to be moving at the exact same speed for everyone, no matter if you are moving towards it or away from it. This is why both observers would see simultaneous lighting bolts.

The only thing that changes is the speed of time.

[jlin91]

pretty good i liked it sums it all up pretty much nothing really you left out or was in excess :) good job :)

[EH3Films]

Thanks very much for the comments, glad you liked it :)