ye olde twin paradox - ozmoroid responds

[jbz3]

Wow I can't believe I understand this now! I watched your 5 relativity videos, then came back to this, and it all makes sense now!

[txvoltaire]

So, uh, when go they crash?

[1zacster]

@kristijanadrian I don't get the twin paradox, pleae explain it to me

[WaiteDavidMSPhysics]

@1zacster I thought he did. Anyway here's a basic equivalence way of looking at it:

watch?v=8stc9OtTUOA

[Madman1234855]

my brain hurts

[QW5ub255bW91cw]

uhhh.. Time..



[Redrum2381]

Even though in a visual model the three events happen at different times and we suppose the subjects would nottice this, I think they would not. I think that instead of a paradox this is just a mental glitch in humans that we have a hard time compensating for. For instane if you had never seen the color purple, then were asked to think of a color you had never seen, you would not think of purple. I could be off on this but this is my first reaction to learning about this paradox.

[jaimesthesaint]

I couldn't understand any of this because I couldn't tell which one was red and which one was green (I'm colorblind)

:(

[Serpico261]

fascinating video!!!

[quidproquo2004]

Haven't you written your coordinate transformations incorrectly? Shouldn't the relativistic factor read gamma = ( 1 - beta^2 ) ^ (-1/2) , where beta = v/c ?

[ozmoroid]

@quidproquo2004 I used the notation beta = 1/sqrt(1-(v/c)^2) which is what Einstein used in his original paper. Many texts use the notation you mention. I also chose units in which c=1.

[quidproquo2004]

@ozmoroid Yes, I see that now.  Thanks for the well done and informative vid.

[Flyborg]

One thing I've never understood is how speed is relative, but the speed of light is constant. Example: You have 2 planets which are stationary relative to each other. A ship is launched from the first planet on it's way to the second. The ship reaches light speed, and launches a smaller ship from itself. If motion is relative, shouldn't the 2nd ship be able to reach the speed of light relative to the first ship, which is moving at light speed relative to the planets? So who gets there first? :o

[ozmoroid]

@Flyborg Yes, the 2nd ship can approach the speed of light relative to the 1st ship, but to relative to the planets the 2nd ship will not exceed the speed of light. In relativity velocities don't simply add. There's an "addition of velocities" formula that can never exceed the speed of light.

[Flyborg]

@ozmoroid But then the question is, if the 2nd ship is moving at the speed of light relative to the 1st ship, and the 1st ship is moving at the speed of light relative to the planets, who arrives at the destination first? From the planet's perspective, both ships are moving at the speed of light (equal speed) and should arrive at the same time, but from the perspective of the 2nd ship, they're moving far ahead of the 1st ship at the speed of light. This is the part I don't get.

[ozmoroid]

@Flyborg Only massless particles (e.g. photons) can travel at v=1 (speed of light). But, say the 1st ship travels at v=0.9 and the 2nd travels at 0.9 relative to the 1st. Then the 2nd travels at 0.99 relative to the planets. Say the planets are 1 light year apart. When the 2nd arrives the perceived elapsed times are: planets-1.006, 1st-0.242, 2nd-0.106 When the 1st arrives the perceived times are: planets-1.111, 1st-0.484, 2nd-1.111

[ozmoroid]

@ozmoroid Each frame of reference perceives different velocities, times and distances such that they all see a consistent physical picture.

[Flyborg]

@ozmoroid Basic math is my Achilles heel. :( I was just thinking in relative terms. If a ship is moving at ~c (almost the speed of light, lets say 99.999%), it should reach a planet 1 light year away in NO LESS than 1 year. Reaching it any faster would be impossible due to the light speed barrier. But if it launches a 2nd ship which is also moving at ~c relative to the first, then the 2nd ship should see the 1st ship get left in the dust as ship 2 shoots ahead. And yet they must arrive together.

[ozmoroid]

@Flyborg You are correct in that the planet frame of reference will perceive them to arrive at almost the same time. But the ships will see each other arrive at very different times. The problem is that when we try to visualize this we use our intuitive classic space/time concepts, but those get thrown overboard near the speed of light.

[Flyborg]

@ozmoroid If everyone experiences different things, this sounds like a Star Trek style paradox. Visual anomalies aside, there should still be only 1 "real" location of objects, regardless of skewed observations. But it sounds like the crew of the 2nd ship which arrives first could land on the planet, greet the inhabitants, and then wait several months until both ships arrive at the same time.. and then the crew of ship 2 could greet the crews of both arriving ships.. including themselves.

[Flyborg]

@ozmoroid [cont.] The problem is visual I guess. If I'm in a small plane launched from a larger one, and I hit the throttle, and look behind me to watch the plane I was launched from rapidly shrink until it's just a little speck in the distance and promptly disappears, then when I arrive at my destination, I shouldn't look to my side and see the plane I was launched from right next to me or just behind me, as I "left it in the dust". (I hope I'm not using creationist logic here)

[fatfist]

In Relativity, ALL motion is relative. It is JUST AS VALID for the twin on Earth to be in motion, while the astronaut is motionless, making him the elder twin in the end.

Two different outcomes occur, based on which IFR we consider.

RELATIVITY DEBUNKS ITSELF!

[ozmoroid]

@fatfist The difference is that one of the twins changes reference frames in order to return to Earth. That is where the symmetry breaks down and why the Earth twin is older than the other.

[fatfist]

@ozmoroid

"one of the twins changes reference frames in order to return to Earth"

An IFR is a concept, it's not an object like a "bedsheet", that can be changed.

All motion is relative in Relativity. An IFR is a "mathematical" concept, with no physical reality. It is defined by setting up the domain or co-domain coordinates in a transformation. The transform can go in either direction, just like a person in a train in constant motion watching a stationary train.

[fatfist]

Depending on how you set up the transform between domain and co-domain, either the astronaut or the Earth bound sibling will be shown to age.

This contradicts the asserted conclusion of the Twin Paradox.

[ozmoroid]

@fatfist An IFR is a frame of reference in which the law of inertia holds. This is physically observable. The ages of the astronauts do not depend on how you set up the coordinate systems. It depends on the relative physical motion. The point is that one of the travelers will have to change reference frames and that would be accompanied by an observable acceleration. This is why the ages are not symmetrical.

[fatfist]

@ozmoroid

"This is physically observable"

Since you claim that an IFR is an object you can observe, please reference a picture of this object so I can see it for myself. Then we'll both know if it's "physically observable".

"The ages of the astronauts....depends on the relative physical motion."

Yes, that's what Relativity is about: absolutely ALL motion is relative!

[fatfist]

"The point is that one of the travelers will have to change reference frames"

The astronaut is in reference frame S' while the twin on Earth is in reference frame S. Please explain how the astronaut can magically change his location and magically appear on the Earth.

To an outside observer who models this situation with relativistic math, the astronaut remains in S' until re returns and "lands" on Earth, at which point he is in S again.

[fatfist]

"an observable acceleration"

Acceleration or inertial motion has nothing to do with it. Remember: Under GR, ALL motion is relative. Not just uniform motion.

This is why the age of any twin is "relative" to whether it is calculated from the domain or co-domain frames.

[fatfist]

Remember: Just like a person in a moving train is an absolutely stationary frame with a "viewable" stationary train, and vice versa. It is the same situation with the twins.

This is what Relativity is about. This is why it's called: Relative Motion.

The situation you are attempting to describe is "absolute motion". This is prohibited in Relativity.

[ozmoroid]

@fatfist No, I am not referencing any "absolute motion." I am talking about a change of reference frames for the return trip and that change would be accompanied by a physically observable acceleration.

[ozmoroid]

@fatfist "Acceleration or inertial motion has nothing to do with it." It has everything to do with it fatfist - I suggest you make a video explaining your objections. Work out the math and show that the results presented in my video are incorrect.

[ozmoroid]

@fatfist I get the feeling that you didn't bother to watch the video because this is clearly explained.

[ozmoroid]

@fatfist No, I did not say an IFR is an object. I said it is a frame of reference in which the law of inertia holds. This is physically observable. Yes, the law of inertia is physically observable and provides a means for determining an inertial frame of reference.

[kid0147]

I don't get this :(

[gimmethegepgun]

I hate relativity :(

Very good explanation though, I think my head is mainly intact afterwards

[Myrtone]

What's that didgeridoo opening?

[tennismike22]

Lets say along the space ships track are even amounts of radioactive matter that decay at the same rate, and time is determined by looking out your spaceships window to see how much of the matter has decayed. if you were standing still or in that fast spaceship you would measure time the same. True?

[raesnake]

we have a project about the twin paradox....

this video was better than what i've read and watched about this theory in relativity'....

but i cant fully understand the twin paradox....

could u give me an advice regarding this???

tnx!!! ^_^

[Kurtlane]

Thank you very much. This is the best explanation of the twin paradox I've ever seen.

[ozmoroid]

You are most welcome.

[Zubinen]

What's the point of this video? It's obvious to people who already understand this concept and people who don't understand this wouldn't watch videos of this type anyway.

[HKragh]

What do you mean by "Obvious"? I still dosn't find it "Obvious", even though I have some knowledge and much interest in the field. I like the graphical way of showing this, and found the video great.

How arrogant.

[jgough1993]

For people like myself who had to lern it. It was compulary for year 11 physics to learn about the Twin Paradox, and then teach it to other year 11s

[jgough1993]

I cannot believe that they teach this in year 11 physics in Australia, no scrap that (THEY EXPECT THE STUDENTS TO TEACH IT) nice try at this man, but i stiil don't get it.

[hackenbollox]

Ecellent work.

[jlmadill]

Nice video, but this is not the twin paradox. The paradox is not that one will age 8 years and one 10, but that, since while in motion each twin witnesses the other experiencing time dilation, then how, upon reuniting, can there be an asymmetric experience? TO answer the paradox one needs to talk about acceleration, decelation, and reference frames -- which are totally absent from this video. While not exactly the twin paradox, this video is nonetheless a great explanation of time dilation.

[ozmoroid]

jlmadill - thanks for comment. The key to the twin paradox is that one of the twins changes reference frames. I tried to illustrate that using the red, green and blue reference frames. Each frame sees time dilation in the other two, but the "handoff" occurs at different times in the three frames. If you use Gen. Relativity with an accelerating frame, and let the accel. become infinite for 0 time, you get the situation illustrated. See also my follow on vid watch?v=-mtxASNWD_s

[michalchik]

Wait, you just said that the speed of light is constant in inertial frames of reference. Does that ,mean that the speed of light does not have to be constant in non-inertial frames of reference?

[ozmoroid]

Yes, the speed of light is not necessarily constant in a non-inertial frame of reference. In fact, the reduction of the speed of light for radio waves traveling near the sun has been measured.

[jgough1993]

but if the speed of light is not constant wouldn't that effect the whole universe? and completely screw up every theory and application of light waves that uses the speed of light as a constant?

[ozmoroid]

The speed of light is constant in inertial frames of reference, but not necessarily in other frames or in gravitational fields. This is consistent with relativity theory.

[FlightIsLife]

VERY Illuminating, ive never heard it explained as well as this (possibly because ive never heard it explained by someone who fully understood it). Thanks!

[555D3M0N666]

wow.... thats a trip isnt it

[reasonintheright]

The traveling twin worshiped Jesus so he slowed down time for him but the other twin was a damn atheist so time stayed the same for him so he died first. I swear Einstein said this on his death bed so relativity is just a lie from Satan like evolution.

[AlanKey86]

I'm not sure this question answers dprjones' question.

My understanding is that the twin "paradox" arises because of Special Relativity, but can only be resolved with General Relativity. The video does not appear to address the inevitable acceleration that the twin in the Red/Blue rockets experiences.

Nonetheless, it is an excellent video for explaining how the twin paradox arises.

[ozmoroid]

//The video does not appear to address the inevitable acceleration that the twin in the Red/Blue rockets experiences.//

The acceleration occurs when the twin changes spaceships. In this scenario it would an infinite acceleration for an infinitesimal amount of time. You can extend this idea by having multiple frames of reference with small differences in velocity, but the bookkeeping certainly gets messy.

[foulplay2]

I've watched this video around ten times now, and am still struggling to wrap my mind around it. I understand the math but it's hard to understand WHY it works for me.

[thebeardedone]

Excellant illustrations! I wanted to watch the animations over and over again.

[ozmoroid]

Really glad you liked it. Hope it convey some useful information.

[LGreener25]

ow!..... my brain.....it hurts!

[Ripley747]

Based on this paradox, does anyone know if it's possible to NON-arbitrarily define a point in space that is "not moving?" From what I understand, in effect, the faster you go, the slower time goes (relative to us). Therefore, it would make sense that if we find a velocity relative to us that makes time move faster than any other velocity, then that point should not be moving in theory. After all, we know the Earth is moving through the universe. Has anyone ever tried this? Would it even work?

[ozmoroid]

It is not possible. Every non-accelerated frame of reference can consider itself as the "not moving" frame. The time dilation effect only depends on the relative velocity between reference frames, not on any idea of "absolute motion."

[Ripley747]

That's kinda what I thought but I am still a little confused. Are you saying that if you are the one who is accelerating and your twin is not accelerating, then you will be the one who ages? If so, that kinda makes sense, and I would also ask why time doesn't "go back" to the "non-moving" frame of reference when they reach the speed of light and not accelerate (or their max speed at close to the speed of light)? I'm going to check out your follow up now. Thanks!

[dwoclan]

Your wicked smart.

[JustAnAdjunct]

My brains are splattered all over the wall, because you just blew my mind man =O

[TinyCoconut]

Ozmoroid. This vid is a tidy little masterpiece!

[sjw4ng]

good job! can you explain the barn paradox?

[addmoreice]

yes please do!

i can understand it from a math point of view, but i've never been able to visualize and conceptualize how this one works in a visceral sense like i can the twin paradox.

[unaka2012]

Great! Excellence response video!

I can say, without a doubt, that I almost understand it ;)

[ndjarnag]

Question: If all colors emitted radio waves, would the result be ths same?

[ozmoroid]

Yes. There would just be a bunch more lines flying around in the figures.

[carrierexchange]

Very interesting! Great video! 5*

[coldsun1979]

Great ozmoroid, learned something relatively new today :D

[ionz75]

Freaking creepy!

[qanazir]

The mechanics of Time (and space!) do indeed change, depending on the circumstances, velocity being a crucial one.

They're but realitve concepts and not constants.

[325982668]

I love the Didgeridoo but the rest of the intro still scares the hell out of me, great vid though

[antiantiantifahool]

do you have a video or plan to make a video shwoing the speed of light to be constant in all frames of reference? I mean Maxwell's equations and stuff.

[DustyMay1944]

addmoreice;

I think you'll need just a little more science background to debate science with scientist! There is not enough characters permitted on YouTube to get into an indepth discussion. The type of confusion you have is what I've attempted to correct when laymen regurgitate inadequate science text.

[addmoreice]

again, i understand it perfectly well. i've done tensor calculations. i'm currently researching how to produce processors that do tensor calculus a tiny bit faster. this is my area of research.

the fact that you think that relative in this context means subjective and you think that there IS such a thing as 'absolute time' instead of a dimensional construct tends to make me think your the one lacking knowledge here.

[DustyMay1944]

If you had read and understood what I said you would not need to retranslate my words to what you THINK I said. The tactic called "putting words in my mouth" is asinine and childish in an attempt to declare yourself the smarter.

Read again: The math works; no argument. The "INTERPRETATION" of the math is wrong. The twin paradox is not a consequence of the math (Relativity) but of the different influence that the different motions have on the atomic behavior of objects and measurement.

[addmoreice]

and again, i get what your saying.

I say it again.

your wrong.

it is not an effect of motion on the rate of particle vibration, or particle decay, or measurement of particle spin or the fifty OTHER all co-confirming effects that show time dilation, and to the EXACT rate predicted by relativity.

your saying 'the clock slows down, not time'

I'm saying NO.

many different TYPES of clocks are ALL slowing to the EXACT rate predicted EVEN when no motion occurs but only gravity is applied.

[DustyMay1944]

My wrong says you're wrong.

Using "your" for "you're" once or twice is forgivable. You've exceeded your limit. YOU'RE giving me doubts of what you claim.

I'll give you some time to stop letting the math dictate reality for you. It works only due to the fact that spacetime is just another name for "ether" or "quantum foam". Don't turn science into a religion by preaching science doctrine without questioning it. You're not questioning, you're just believing!

Have fun SFB.

[addmoreice]

yes, point out my spelling and grammar, surely that makes you right!

all that aside, I'm sorry that YOUR [sic] so annoyed by the fact you have been shown to be wrong.

again. the math works. saying 'there is ether! the foam knows!' does not mean this is so. provide EVIDENCE for your claim. all the 'ether' arguments fail to produce the results experiments dictate to be so, and the "quantum foam" and even loop quantum gravity DO suggest time dilation effects.

[addmoreice]

saying i'm simply swallowing 'doctrine' is silly. do you see above me asking for EVIDENCE of your claims?

not just bluster but evidence?

you made a claim (the clock is slowed my motion not time) then i point out in TWO WAYS why we know this is not so.

see how that works?

either provide evidence or simply retire from the field till you find evidence that does support your claim.

I'm willing to reconsider my views on this, simply provide the evidence commiserate with the claim.

[DustyMay1944]

The evidence shows that the accelerated clock runs slow.

The evidence shows that gravity has an index of refraction.

The evidence shows that length contraction (as predicted by Relativity) is wrong. All dimensions of an object contracts under acceleration.

Relativity is a gauge theory that predicts the numbers not the meaning of the numbers!

Where again is that evidence that time dilates?

[addmoreice]

1) yup as it should.

2) never seen that research. everything _I_ have seen shows gravity effects in straight lines (through 3d space) and has NO index of refraction.

3) every paper i have read has indicated either length contraction exactly in line with relativity or involved a failure of experiment (though not of the theory). what pier reviewed paper indicates this? reference please.

the evidence of time dilation is above. time dilation of exact amount predicted under acceleration AND gravity.

[DustyMay1944]

"There are no absolute measures of time nor distance". The measurements are dependent on the observers (subjective). The actual slowing of the clock is a physical phenomena and thus an "objective" observation; you cannot say that the relative states of the observer is what caused it. The twin paradox does not prove Relativity predicts actual physical phenomena. It only gives understanding to the process of measurement variance.

I'm using the same data and text you are.

[addmoreice]

"The measurements are dependent on the observers (subjective)"

NO they are NOT subjective. they are RELATIVE.

RELATIVE from one frame of reference to another. if i do the measurements FROM MY LOCATION but using your relative frame i can predict YOUR time dilation. it's not subjective, i don't think it 'feels like' time has slowed.

time HAS SLOWED.

and it's not JUST motion that changes things.

a GRAVITY field does as well. explain THAT.

relativity _does_ you have not.

[addmoreice]

your arguing that motion throws off the clocks. time isn't slowed. it just seems like it.

except we wouldn't expect different TYPES of clocks to be slowed the same way or the same amounts. if this type of effect was artificial and not an inherent property of the time dimension then we would expect a cesium vibration clock to be effected one way, a photon bounce clock to be effected another way etc etc. we don't see that.

[cont]

[addmoreice]

and furthermore if it was ONLY the effect of motion then we should NOT expect to see the same effect when we instead simply use a gravity field. we should expect to see the effect only when moving.

we see this effect with just a gravity field as well.

it's not simply motion throwing off the clock.

it is actual, factual, time dilation.

[DustyMay1944]

OZ;

Relativity is a subjective theory. Attributing the aging process or the slowing of the clock to subjective observations is not science. Time is immutable; the measurement of time is not. The objective data is the result of the influence of motion on the physical behavior of the objects. Relativity is just a convenient way to compensate for the physical processes that occur. Common sense requires common knowledge but logic will lead to truth. If it's bazaar, it's wrong.

[addmoreice]

sure, because when common sense said the sun revolves around the earth, common sense wins out.

NO.

EVIDENCE wins, not logic, not common sense, not personal bias or belief.

EVIDENCE.

the _evidence_ says that the OBJECTIVE result of making a measurement to the _relative_ position changes the measurement (and in fact the underlying actuality).

relative, not subjective.

look up the two words. figure out what they mean. they do not mean the same thing.

[DustyMay1944]

It is not the evidence that is in question; it is the interpretation of the numbers. The interpretation is saying that the position of the observer is influencing the measurement of time; that IS subjective. I'm saying it is the difference in the state of an observer's "absolute motion" that influences the measurement of time. The measure of time (a clock) and proper time (universal) are not the same. We do not a a universal reference that would allow for the measure of proper time.

[addmoreice]

I get what your saying. i'm still saying your WRONG.

1) there is no 'objective observer' thats a direct consequence of the theory.

2) it's not subjective. the results match predictions out to a very high level of accuracy. it's RELATIVE not SUBJECTIVE the two terms are not the same.

my measurement RELATIVE to another measurement is correct. the measurement device didn't some how become innaccurate. it's the time that i'm measuring that dilates.

otherwise why would the measurements agree?

[DustyMay1944]

You cannot attribute time dilation to proper time; only to measured time and that is a clock that is influence by the differences in relative motions; not relative positions.

[addmoreice]

so....the experience of time and what we measure it acts just like time in einsteeins equations say it does but this has no relation to 'true' time but then we can never experience and measure 'true' time?

you do get how silly that 'argument' is right?

[addmoreice]

bah spelling.

anyways. lets try this another way see if you can get where your getting this wrong.

would you expect to experience the same acceleration due to gravity on pluto that you would on earth?

in the same way why would you expect to have the same 'time acceleration' when accelerating as you would when NOT accelerating?

but then in BOTH systems you have chosen an arbitrary relational frame...and hence a different frame would see different relative results. SEE?

[DustyMay1944]

To measure proper time, one requires a fixed reference that does not change it's location in the universe, thus our only option is to develop a time measuring system that is based on something that renders the same numerical value regardless motions. The measurement of the speed of light in a vacuum provides this constant number and thus the means to correct and compare observations. I think saying that the universe changes its motion (time dilation) for each observer is the silly notion! :)

[addmoreice]

and again your wrong.

the speed of light is a constant IRRESPECTIVE OF MY VELOCITY. if i travel a thousand miles per hour relative to something else or 2. the speed of light is constant for BOTH.

a+a != 2a

relativity explains this. why do we FEEL like this is wrong? why does a snail not notice wind resistance?

the _only_ interpretation of the data that makes sense is that the _time_ we measure between the events has changed. it's the only interpretation that fits the data.

[DustyMay1944]

Again you make a very common error that is made by many laymen and just plain ignorant people: "The MEASURMENT of the speed of light in a VACUUM is constant."

Since you don't have a science background it is useless to try and educate you on YouTube. The Stanford channel has many excellent lectures on the topic if you have sufficient background to follow them.

Sorry addmoreeice, but to me you are just another neophyte going through his young and dumb phase of life.

[addmoreice]

ad hominem. sure sir that convinced me.

yes it's the speed of light in a vacuum that is a constant. i get this perfectly well.

AND? it's the same speed IRRESPECTIVE OF VELOCITY OF THE OBSERVER. _thats_ what lead to this conclusion. thats why this is important.

i am perfectly aware that the speed of light in OTHER material is lower (and i am even aware of Čerenkov radiation which is a result of this fact), and by the way i DO have a science degree. a young age does not mean ignorance.

[DustyMay1944]

Do you realize that your #2 contradicts your #1. You can't have it both ways!

[addmoreice]

um, no it does NOT contradict it. i say it again so maybe you will understand. relative is not the same as subjective.

it is purely objective. we pick a reference frame then measure. the result is NOT subjective (up to the person) it's up to the REFERENCE FRAME.

just like if i say 'what is my velocity' it depends on what frame of reference i pick. if i pick relative to earth i get something far different then if i pick relative to the sun, and if i pick relative to the galactic center.

[addmoreice]

again, the fact there is no objective observe does not mean the measurement is subjective. it's RELATIVE (and hence the name of the theory) to a frame of reference.

the math works. if you don't like the theory find a better one that explains the facts.

8 years of college (i have 5) and 40 years experience as an electrical engineer. cool. I have 5 in computer science, are either of these relevant to physics?

well I'm doing my research on speeding up tensor calculations, so a bit.

[addmoreice]

either way, it's not the AMOUNT of education brought to the board (we both know argumentum ad authoritate doesn't work). It's the evidence.

the evidence _I_ have is that in every test of the theory it has shown to work perfectly well to explain the massive and the fast moving (though not the quantum).

your claiming it doesn't work.

ok, present your evidence sir.

[addmoreice]

here lets start right from the top. MOTION is not the only way to slow time. a gravity field is all that is required (acceleration is equivalent to a gravity field, another consequence of relativity).

hence an atomic clock on the top of a mountain should run slower then one at the bottom.

does this happen? yes it does. no motion needed.

and even by the amount EXACTLY predicted by the theory, imagine that!

[addmoreice]

rofl! strike that reverse it! the one at the bottom should run slower [smacks self in face].

larger field, greater dilation.

[collieh1]

DustyMay1944.

The big confirmation of relativity was when muons where measured at the top of a mountain and at the bottom of the same mountain. We knew the half life of muons and could predict the expected number of muons that would reach the bottom. However, unless time dilation was factored in, the measured muons at the bottom of the mountain was much greater than the expected amount. The muons were traveling at almost the speed of light, and time slowed down for them a lot.

[addmoreice]

man this has to be the worst way i have ever explained this but ugg whatever.

accelerating 'pulls' on the fabric of space and time. the faster the acceleration the greater the 'pull'.

just like the acceleration we experience on earth is different for different planets the time we experience is different based on the accelerations.

[cosmicism]

fuck cant wait till i start learning this in univ

[MetalAtheist93]

We need to try this in real life!!!

This is the only reason we need to develop space travel!

[crazychessman]

"Of the many things that come out of relativity THEORY..."

Relativity is only a theory! The fallacy of your entire presentation follows form this fact! It's just deception by the Devil to convert weak-minded Christians to the contemptible philosophy of methodological naturalism! Different times in different frames? Blasphemy! Only a mindless atheist can accept such an obvious absurdity!

Sorry, had to take the bait. This and all your other videos are excellent. I happily await the next one.

[ozmoroid]

And they want to teach this in our schools! Why don't they teach the controversy!!!

[oscar2k]

Nº 100 ... 5 Stars ^^

Nice vid :)

[zebruh]

Absolutely, indescribably, unbelievably fascinating.

I've known that relativistic effects are real and fundamental to GPS, but every time I hear about it i am just dumfounded and amazed. Thanks for this superb video.

[mortemdei]

Excellent!!!!

[endergt]

I love your ability to explain things in a simple yet technically accurate manner. Thanks for another great video!

[Singebuggercat]

Incredibly well done. That's the closest I've ever come to understanding relativity.

[Josan117]

Nice explenation, I really liked the fact that you used 3 space ships, as I've only heard of it using 2 space ships, which makes the whole thing about there being more than 2 refrence frames easier to grasp, I will definitly use 3 space ships if I ever try to explain it in the future.

[ozmoroid]

Thanks. The change of reference frames for the "younger twin" is the key to the "paradox." If they both stayed in single reference frames their experiences would be symmetric (both would think time was moving slower for the other twin) but they could never get back together again.

[pocoapoco2]

If we put an atomic clock on Mars, what would we see as a result? Would we need observers on both planets in order to be able to verify the results? There is points in time where Earth and Mars are receeding from each other at fair rates of speed as well as approaching each other. I'm wondering if Michaelson-Morley failed only because they were limited to orientating their apparatus in only three dimensions.

[androgenik]

ozmoroid, what program did you use to make the animations?

[ozmoroid]

povray to render the frames and virtualdub to assemble them into video. Both are free online.

[JRBendixen]

Congratulations with the 1000 subscribers.

Cheers :)

[ozmoroid]

Many thanks!

[SIASLbyRAH]

I thought "velocity" was a direction and speed. Wouldn't either 1 or 2 be moving at velocity "-v"?

[PygmyLepper]

Yep, but tis a small mistake, can be easily overlooked.

[ozmoroid]

Correct. We can express that as +/-v, as shown in the equations, or as opposite vector directions, as shown in the figures (e.g., 0:20 ). We can say that the blue spaceship moves to the left with velocity v, which is the same as moving to the right with velocity -v.

[SIASLbyRAH]

I agree it COULD be easily overlooked but it's a pet-peeve of mine which comes, in part, from watching sci-fi shows like STNG in which Data (of all "people") advises the captain that the Enterprise is traveling at a "velocity" of warp 5.

[RyuDarragh]

One additional way of helping the confusion about time changing when v approaches C is to remember that old chestnut about gravity being a spatial curvature. When it was finally verified by observing light being bent by passage through the suns g field during an eclipse, it was also noticed it was slightly red shifted. Every object curves space. The faster they go, the steeper the curvature. The steeper the curvature, the slower time passes for those inside that curved space.

[dave28lax]

Excellent explanation - that made a lot of sense, and was relatively (!) straightforward to follow.

Thanks. I think I'm gonna like this series from dprjones.

[Kajio3033]

I finally understand this now, thanks! Now if you can explain black holes and quarks, I'll be set!

[limeffdd]

Well said, :)

[Stegocephalian]

That was very interesting, and ultimately illuminating too, though my poor brain needs to cool down for a while now, methinks. :)

[whoarentyou]

enlightening, i'll have to watch it many times more to understand it better though.

great explanation.

[yaddah3]

I think it was Albert Einstein or maybe Britney Spears.

[draagon66]

"The more I know, the less I understand."

Who said that?

[ImposingSumo]

Paul Weller, "Changingman".

[draagon66]

ImposingSumo

I have this odd feeling that John Lennon also said it.

Then again, i don't get out much.

[Verrimgard]

Buh? Agh! My brain! What have you done!?

Something seems screwy about all this. I mean, even if events occur more slowly in one place, how would that mean less time passed? Time is just a concept isn't it?

Like, what if you froze one twin and thawed him out ten years later. One twin is 10 years old, the other still a baby. Or are they both ten years old, but one had been frozen?

Damnit. I don't get any of this.

[addmoreice]

if you freeze them in suspended animation then yes, neither of them would age...but this 'paradox' demonstrates that while neither of them would 'age' per say they both would experience different amounts of time. thats the point of it.

while it seems contradictory to the way we normally deal with things, it never the less is observed to work this way.

the best short answer i can give why we never notice this is:

why don't snails notice wind resistance?

same idea.

[yaddah3]

The twin paradox , which I found very interesting when I read about it as a child, seemed always to involve a round trip on one spaceship. Just a trivial question - how does the twin survive bodily the transfer between the two ships - the change in inertia, would be significant. Really enjoyed the video, I guess I just wanted to point out any analogy has to have exceptions to a real world example.

[ozmoroid]

The "transfer" twin would be in a world of pain - "pancake twin." More realistic would be to exchange a signal recording the elapsed time.

If you do it with a round trip on one spaceship then that spaceship needs to accelerate and special relativity doesn't work quite right.

[jamminjago]

what program did you use to make the animation with all the dots?

[ozmoroid]

povray to render the frames and virtualdub to assemble them into video. Both are free online.

[11mc22]

This is hurting my brain

its a bit confusing

[thorungal]

loved the animation. made good sense.

[Weirdo10o4]

*Brainhurt

[thorungal]

I can't relate, I already understand special relativity. Haven't tried general relativity yet.