The Science Behind Time Dilation: How Does Time Stop at the Speed of Light?

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In summary, time is affected by motion and appears to slow down as an object approaches the speed of light. This is demonstrated through experiments involving light clocks and the decay of particles at high speeds. This phenomenon is known as time dilation and is a fundamental concept in the theory of Special Relativity.
  • #36
physicscrap said:
I still don't understand. In space... there are no real forces acting upon you. Just you and your ship traveling close to c. So you are basically standing motionless because you are at a constant speed, and nothing else is acting on you. So, with that said, whatm akes that any different from standing on Earth with a clock? Doesn't seem to be any different. I do not understand how time actually slows down. I understand howthe photon takes longer to bounce which make that TYPE of clock slower, but not a mechanical clock. Because what force is acting upon the gears of a clock while traveling close to c? nothing right? I do not understand how the distance is actualyl shorter, though it could be MEASURED shorter relative to the PHOTON clock, not a normal clock. I just don't see how you think slower since you are ...motionless...

I understand tiem as a universal measurement. It never changes. You could be going 1000 X c(not possible so far) and the time will still be the same but you would be hauling ass everywhere and would not be seen. I just don't get it, plain and simple, and at the moment I am calling you and all the geniuses idiots, because this seems obsurd and beyond the point of sanity. But I want to understand this if it is truly true, and I will continue to expand my understanding of it.
If you start with the assumption that time is absolute, then any logical path you take from that will lead to the physical contradiction you are seeing. The assumption that time is absolute is in conflict with OBSERVED REALITY. You really need to accept that fact. Launch a clock into space - any kind of clock that has sufficient accuracy - and then bring it back to Earth and it will not match a clock that has stayed on the ground.

To me, the key concepts here are the facts. Start with accepting the facts and everything else will fall into place. (Caveat: yes, it is true that time dilation was predicted before it was observed, but to an incredulous learner, it is a heckuva lot easier to accept something that has been observed than something that has "merely" been mathematically predicted.)

So to go back and answer a couple of questions there:
In space... there are no real forces acting upon you. Just you and your ship traveling close to c. So you are basically standing motionless because you are at a constant speed, and nothing else is acting on you. So, with that said, whatm akes that any different from standing on Earth with a clock? Doesn't seem to be any different.
Forces? No forces - it is time itself that is relative, so of course, no forces are required. If forces were involved, that would imply that it wasn't time itself that varies.
I do not understand how time actually slows down.
There is no "how". It can (and has) been explained as a logical consequence of observation or simply as an observation itself, but a mechanism is too much to ask for at this point. We don't have a mechanism for gravity, for example, but that doesn't stop us from understanding what it does.
 
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  • #37
physicscrap said:
I understand how the photon takes longer to bounce which make that TYPE of clock slower, but not a mechanical clock.
Okay physicscrap, I added bold to your above statement to drive home the fact that you're not thinking about this statement enough. The photon does NOT take longer to bounce between two mirrors; remember that c is constant. So what does that mean??

The photon traces a path that's longer than twice the distance between two mirrors from the perspective of an observer, but traces a path equal to 2d from the perspective of the mirrors. So what gives? Who is right? Did the photon travel distance 2d? Or a distance greater than 2d?

But remember that Distance = Rate x Time, and Einstein argues that the rate of the photon never changes, so either distance or time must give...
 
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  • #38
ok so time just slows to an observer... How does a clock look slower from an observer? I still don't understand how "Launch a clock into space - any kind of clock that has sufficient accuracy - and then bring it back to Earth and it will not match a clock that has stayed on the ground." works. It is not clicking for me. Because you say there are no forces, just time. Well a clock that measures time via gears is somehow affected according to you, how is it affected in such a way that is slows down?

grrrahawrwafhawofghoaw;gou;wa! you I am confused
 
  • #39
Again, the only way around this is to stop thinking that the clock slows down. Time slows down. Nothing at all happens to the clock.
 
  • #40
physicscrap said:
ok so time just slows to an observer... How does a clock look slower from an observer? I still don't understand how "Launch a clock into space - any kind of clock that has sufficient accuracy - and then bring it back to Earth and it will not match a clock that has stayed on the ground." works. It is not clicking for me. Because you say there are no forces, just time. Well a clock that measures time via gears is somehow affected according to you, how is it affected in such a way that is slows down?

grrrahawrwafhawofghoaw;gou;wa! you I am confused

First let's deal with the mechanical clock vs. light clock issue. Remember that your mechanical clock itself is held together by electromagnetic forces. And these electomagnetic forces make themselves felt from atom to atom at the speed of light. So the forces holding the mechanical clock together form tiny little light clocks inside the mechanical clock itself.

The second issue is when you say:
I understand time as a universal measurement.

But time isn't a universal measurement, it is a relative one. I know that this is a hard concept to grasp, because in everyday experience time sure seems to be a universal measurement.
You and a friend sychronize your watches, and he goes off on a train trip. You are sure that at any given moment you both will agree that your watches read the same time. When he returns, you compare watches and they still read the same. From this, and other experiences, you conclude that time is universal.

The problem is that at the speeds we normally deal with, the Relativity of time is just not apparent. Your watches don't read the same time, it's just that the time difference is so small you'd never notice it.

An analogy is this:

Over small areas, the surface of the Earth seems flat. For centuries, people believed this to be true. As a result, "down" was considered a universal direction. Someone pointing down at one point of the Earth would be pointing in the same direction as anyone else at any other point. This is like universal time.

Of course the Earth's surface isn't flat, it is curved due to the Earth being a sphere. As a result, people standing on different points of the Earth point in different directions when they point "down" (if I was standind on a level surface in San Fransisco, and could see through the Earth to someone in London, they would seem to be "below" me and tilted at an angle. To them, I would be the one "below" and titled at an angle.) This is because we each have our own notion as how you measure "down".
This is like Relative time.

A universe with Relative time behaves differently than one with universal time. You can do experiments that can distinguish as to which type of universe we live in. All experiments to date agree with us living in a universe with Relative time.
 
  • #41
physicscrap said:
I never understood how time can slow down as you reach the speed of light then it stops...

I see time as a measurement by a mechanical clock. One second will always be one second.

My ap physics teacher said they did this experiment. They took a photon or something with a very small half-life. They shot these across a measured distance x and predicted that only like 2% of them should be left when they reach impact or whatever. v=d/t, them knowing the initial velocity and distance, the time calculated showed a ton of decay. But there was 98% left, which they concluded time stopped...

Ya anyways is it the process in which it is decaying that is lowing down, not time itself? Can someone clarify this for me? Like is you traveled at the speed of light, someone on Earth with a stop watch would read 10min, so would your watch right? I need understanding ahh!

I have tons of questions, but it is late!

Thanks

Your problem is your not realizing that different observers will not agree on how fast that clock goes, different frames of reference get different measurements.
 
  • #42
Either the speed of light or time is absolute, but not both. The former is much more consistant with experiment and the principle of parsimony.
 
  • #43
"First let's deal with the mechanical clock vs. light clock issue. Remember that your mechanical clock itself is held together by electromagnetic forces. And these electomagnetic forces make themselves felt from atom to atom at the speed of light. So the forces holding the mechanical clock together form tiny little light clocks inside the mechanical clock itself. "

Well I understand the whole concept of relativity, it is just the clock thing... As you said, there are forces that make a mechanical clock work. But when you say they form tiny little light clocks, how ever that might be, they are not the same photon clocks such that the photon would travel diagonal bouncing between mirrors, thus slowing that clock. So how does the mechanical clock slow down in detail?

If proven to me, that time is indeed relative, it will still make no sense. I grasp the concept of a photon clock slowing down, thus time slows down relative to the clock moving. Relative to the person moving, he is moving normally, but relative to an observer, he is going slow(why? not like you could observe someone bouncing a ball close to c, also you would bounce that ball like once after traveling a long distance lol, possible making you seem slow?).

But for an object to actually slow down when actually going faster is ya, hard to grasp, to say the least.
 
  • #44
physicscrap said:
Well I understand the whole concept of relativity, it is just the clock thing... As you said, there are forces that make a mechanical clock work. But when you say they form tiny little light clocks, how ever that might be, they are not the same photon clocks such that the photon would travel diagonal bouncing between mirrors, thus slowing that clock. So how does the mechanical clock slow down in detail?

But see, the "light clock" is the UPPER LIMIT of an ideal case. If I can show logically that the simple light clock will slow down, I have proven ALL other mechanical clock will slow down. Why? Because at the fundamental level, the clock is made up of tiny fundamental particles that form a solid based on electromagnetic forces, i.e. LIGHT!

If proven to me, that time is indeed relative, it will still make no sense.

This is a strange thing to say. You want "proof"? How about the millions of particle in a particle accelerators, especially the exotic particles that were created in a particle collider that had miniscule life time? What about the muon example that I have earlier?

And again, you are using your "sense" as the "standard" here. Do you think your sense is accurate all the time? For example, if you have a helium balloon suspended from a string in a vehicle that is uniformly accelerating in one direction, which direction do you think the balloon will try to move? Please use your common sense and see if you can answer and explain this.

I grasp the concept of a photon clock slowing down, thus time slows down relative to the clock moving. Relative to the person moving, he is moving normally, but relative to an observer, he is going slow(why? not like you could observe someone bouncing a ball close to c, also you would bounce that ball like once after traveling a long distance lol, possible making you seem slow?).

But for an object to actually slow down when actually going faster is ya, hard to grasp, to say the least.

At some point, YOU have to do the work for you. This means that all of us here can only do so much. In the process of learning something, the first responsibility in getting that education is you. There is no substitution for a good text or written source. As good as PF is, we are limited in our ability to SKETCH, describe, etc... The explanation has been given repeatedly, and it appears that either you still don't understand, or from what I can tell, REFUSE to understand, because you keep using what does and doesn't make sense to you. This of course ignores the FACT that you are already using various theoretical predictions of Special Relativity in many aspects of your life without you realizing it.

To me, that doesn't make sense.

Zz.
 
  • #45
Consider an inertial observer at rest. His mechanical clocks and a light-clock, by construction, agree. The Einstein Principle of Relativity would be violated if a corresponding set of clocks carried by another inertial observer didn't agree.
 
  • #46
physicscrap said:
Well I understand the whole concept of relativity, it is just the clock thing... As you said, there are forces that make a mechanical clock work. But when you say they form tiny little light clocks, how ever that might be, they are not the same photon clocks such that the photon would travel diagonal bouncing between mirrors, thus slowing that clock. So how does the mechanical clock slow down in detail?
Simply put, nothing - neither the propogation of photons in the light clock, nor movement of atoms in the mechanical clock - happens instantly.

The mechanical clock has parts made of atoms that can only interact - AT BEST - at the speed of light (this interaction has nothing to do with light, just with the speed).

There is no such thing as a perfectly rigid body. (If there were, you could make it into a 225,000 mile long pole, extend it to the Moon and send signals instantaneously merely by tapping on it.)
 
  • #47
ZapperZ said:
At some point, YOU have to do the work for you. This means that all of us here can only do so much.
I think ZapperZ hit the nail on the head here. I believe 4 pages of feedback are enough, and that it's your turn to perform an independent inquest...the fact is we've all performed our own personal journeys in this area, and that's the only reason we're comfortable in this topic. It's your turn, physicscrap! :)

Here are some nice links for further research, but the fact is you will find tons beyond this:
Of course, Wikipedia is good
A Standford University page
Written for Independent Students of a USC astronomy course

Please come back with specific questions, everyone here is awesome at explaining stuff. But Zz already said it; we can't overcome your own common sense, only you can do that. Change your perception of reality or not, it's really up to you. Maybe it's all a bunch of malarcky anyway, right?

:-p (I don't think so)

But keep in mind that the theory you are ready to dismiss as nonsense (General Relativity) is so elegant, its equations wrap around all accepted, tried, and true Newtonian equations. The GR equations yield more precise results than the Newtonian ones at ordinary speeds, and they yield correct results at abnormally fast speeds where Newtonian equations break down! Different equations that are strictly better than accepted Newtonian equations! You got to admire that...
 
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  • #48
robphy said:
Consider an inertial observer at rest. His mechanical clocks and a light-clock, by construction, agree. The Einstein Principle of Relativity would be violated if a corresponding set of clocks carried by another inertial observer didn't agree.

Or better, the Principle of Relativity would be violated if those same clocks as viewed by another observer (in relative motion) didn't agree. How can two clocks, sitting right next to other (or moving together, right next to each other), appear to be "ticking" in step according to one observer but are out of step according to another one?
 
  • #49
physicscrap said:
I never understood how time can slow down as you reach the speed of light then it stops...

I see time as a measurement by a mechanical clock. One second will always be one second.

My ap physics teacher said they did this experiment. They took a photon or something with a very small half-life. They shot these across a measured distance x and predicted that only like 2% of them should be left when they reach impact or whatever. v=d/t, them knowing the initial velocity and distance, the time calculated showed a ton of decay. But there was 98% left, which they concluded time stopped...

Ya anyways is it the process in which it is decaying that is lowing down, not time itself? Can someone clarify this for me? Like is you traveled at the speed of light, someone on Earth with a stop watch would read 10min, so would your watch right? I need understanding ahh!

I have tons of questions, but it is late!

Thanks
Consider an electromagnetic wave propagating in free space. We can consider that the electromagnetic oscillations taking place in it are a realiable clock propagating relative to all inertial observers with speed c. Conider two inertial observers located in the space where the wave propagates, moving with relative speed V in the direction in which the wave propagates. They are engaged in a time dilation effect or in a Doppler Effect experiment. In both cases the formulas that relate the periods of oscilaltions depend on V. If V could reach c then the observer considered as stationary could obtain for the period an infinite value and so for him time would stop. But as we know that can not happen.
If ou consider the same experiment in an acoustic wave many interesting effects could occur because we should distinguish three cases V<u,V=u and V>u, u being the propagation velocity of the acoustic wave.
 
  • #50
Janus said:
But time isn't a universal measurement, it is a relative one. I know that this is a hard concept to grasp, because in everyday experience time sure seems to be a universal measurement.
You and a friend sychronize your watches, and he goes off on a train trip. You are sure that at any given moment you both will agree that your watches read the same time. When he returns, you compare watches and they still read the same. From this, and other experiences, you conclude that time is universal.
If you were viewing our universe from outside it however, that would be absolute time?

physicscrap said:
grrrahawrwafhawofghoaw;gou;wa! you I am confused
I'm surprised no body has told you your username sucks. :-p :biggrin:
 
  • #51
hmmm I think physicscrap might be getting confused about the twin paradox.. I remember puzzling horribly about that one, age sweet sixteen, almost every night (maybe I'm exagerating, I was probably thinking about other stuff :P hehe) until I heard about the fact that what distinguishes the guy travelling, away from, and back to the starting point, is that *he* has accelerated and the other guy has not (GR; *very* complicated bizness) ... hence the guy that traveled away is the one that ends up looking youngest when the two guys meet up.

I hope that helps physicscrap. But when u do understand, ull realize physics is wicked and not crap.
 
  • #52
I have a question, is time as we know it, a man made mathematical mechanical apparatus, with regards to the questions and the answers that have been given over the last four posts? And isn't it true, with enough force or wear, anything mechanical can be effected, and that it is with relative certainty that no two objects created (mechanized outside of computer controlled) will ever be or function exactly the same?

Which brings about another set of questions. If that mechanical process is computerized, and both clocks are synchronized to the absolute zero starting point, and both draw from the same power source, would both clocks always remain the same?
Also along that same question, if, both clocks traveled at the speed of light, yet they where separated by the complete length of the ship in which they flew, would they both remain the same at both the start up and stopping point of that ship?
 
  • #53
Holy crap litlbunny, your generous use of extra commas makes it a bit difficult to decipher the flow of your thoughts. I'll offer some answers tho.

litlbunny said:
I have a question, is time as we know it, a man made mathematical mechanical apparatus, with regards to the questions and the answers that have been given over the last four posts?
Why would it be? Man-made apparatuses measure the flow of time using an arbitrary standard (the frequency of a vibrating quartz crystal with a set amount of current applied to it, right?). But if the clocks weren't there time would still pass.

litlbunny said:
And isn't it true, with enough force or wear, anything mechanical can be effected,
Yes, I think maybe. But it depends on what you mean by "affected".

litlbunny said:
and that it is with relative certainty that no two objects created (mechanized outside of computer controlled) will ever be or function exactly the same?
Not sure what you mean here, but in a non-rhetorical sense I believe this is false. Two staples that hold two sets of paper together will I think, for all intents and purposes, function exactly the same.

litlbunny said:
Which brings about another set of questions. If that mechanical process is computerized, and both clocks are synchronized to the absolute zero starting point, and both draw from the same power source, would both clocks always remain the same?
Probably, but only because since they draw from the same power source the two clocks probably remain in the same inertial reference frame together. If one of the two clocks left that reference frame (solar powered??) their synchonization would change.

litlbunny said:
Also along that same question, if, both clocks traveled at the speed of light, yet they where separated by the complete length of the ship in which they flew, would they both remain the same at both the start up and stopping point of that ship?
As long as they stayed in the same inertial reference frame as the ship, yes.
 
  • #54
litlbunny said:
Which brings about another set of questions. If that mechanical process is computerized, and both clocks are synchronized to the absolute zero starting point, and both draw from the same power source, would both clocks always remain the same?
While this is technically true (they would *not* measure *exactly* the same, although the accuracy is astonishing) it is a moot point.

The scientific method in general and the design of experiments in particular account for variations such as this in a number of ways. Multiple tests are done, independent research, testing under different circumstances, these all converge on one answer - and even then the various errors can be mathematically calculated to provide an answer that is accurate to as good precision as the theory calls for.
 
  • #55
Why would it be? Man-made apparatuses measure the flow of time using an arbitrary standard (the frequency of a vibrating quartz crystal with a set amount of current applied to it, right?). But if the clocks weren't there time would still pass.
Okay, but time as the standard that is used in several theories, they use time within reference to this planet do they not? So I guess the question I will ask next of you is, would time still flow if we didn't use our standard understanding of it? And if the ticking of the universal clock where to continue ticking even if we are not using our own understanding of time, then how far does the universal time clock travel and does it encompass the entire universe simultaneously?

Not sure what you mean here, but in a non-rhetorical sense I believe this is false. Two staples that hold two sets of paper together will I think, for all intents and purposes, function exactly the same.
Even though staples I believe are a bad example, I will concede the point if you said paperclips, cause technically one could argue that they are in fact a mechanical apparatus. So let me rephrase that previous question this way. If two clocks are created both with the exact same parts, both are used exactly the same way in exactly the same fashion and environment, would they both keep time exactly, or would they both give a different time to time? Outside of the variables I used in my previous question, what else do you suppose is causing this discrepancy? (Yes I am aware of the studies that have tried to answer this, I am looking for new thoughts on this matter.)

As long as they stayed in the same inertial reference frame as the ship, yes
So you are saying if they do not stay within the same inertial reference point they would not stay the same correct? If that is true, what would the effect be if one person was standing on top of that first clock and another was standing on top of the second clock while both persons where inside that same ship, at both the startup and stopping points while traveling at the speed of light?
 
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  • #56
While this is technically true (they would *not* measure *exactly* the same, although the accuracy is astonishing) it is a moot point.
At what point does it make itself a moot point? (at first glance I thought your entire statement answered this question, but I need more clarification from you to try and see where you are going with this train of thought)

The scientific method in general and the design of experiments in particular account for variations such as this in a number of ways. Multiple tests are done, independent research, testing under different circumstances, these all converge on one answer - and even then the various errors can be mathematically calculated to provide an answer that is accurate to as good precision as the theory calls for.
Would location within the universe be the main reason why there are discrepancy when it comes to clocking time more then any other variables? (Meaning if the Earth wasn’t there, yet the clocks remained in their physical location within the universe, would that be the main reason for the discrepancy if the experiment principles I used remained the same?)_
 
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  • #57
To follow up in general.

If both clocks (computerized) where set at absolute zero starting point at the same location within our galaxy separated by only a fraction of a inch, and one stayed absolutely still (did not move at all, no universal forces could move this clock) while the other traveled at the speed at which our galaxy rotates, yet both remained connected to the same power source (non solar) would their times still be the same or close to the same? Or would time change drastically between the two clocks?
 
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  • #58
litlbunny said:
I have a question, is time as we know it, a man made mathematical mechanical apparatus, with regards to the questions and the answers that have been given over the last four posts? And isn't it true, with enough force or wear, anything mechanical can be effected, and that it is with relative certainty that no two objects created (mechanized outside of computer controlled) will ever be or function exactly the same?

Actually, this isn't true. Consider atoms. (Specifically, stable non-radioactive atoms). They do not "wear out", or change their properties, no matter how much you use them. Also, any two atoms of the same isotope are as far as we have been able to determine experimentally, exactly identical (same mass, same charge, same everything) - there isn't any "manufacturing variation" that we've been able to find.

These are some of the reasons atomic clocks are so astonishingly accurate. It's the atoms themselves that are used to keep the time. The support equipment in an atomic clock is needed only to measure what the atoms do.

Which brings about another set of questions. If that mechanical process is computerized, and both clocks are synchronized to the absolute zero starting point, and both draw from the same power source, would both clocks always remain the same?

Also along that same question, if, both clocks traveled at the speed of light, yet they where separated by the complete length of the ship in which they flew, would they both remain the same at both the start up and stopping point of that ship?

Clocks (even atoms) do not travel at the "speed of light".

If you take a clock on a round trip at high velocities (such velocities will always be less than the speed of light!), it will not read the same as a clock that you left behind. We can see this most clearly with atomic clocks, but at high enough velocities, any-old kludgy clock would detect the difference, even a very primitive clock.

Note that the lifetime of muons serves as a crude "clock" of sorts, and at the velocities that muons travel when they are generated in the upper atmosphere by incoming radiation, the change in lifetime is noticable by the very crude "average lifetime of a muon" clock. If it were not for relativistic effects, muons could never live long enough to reach the Earth's surface - but we observe that they do reach the Earth's surface.

I can't make heads or tails out of your last question, sorry.
 
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  • #59
pervect said:
Also, any two atoms of the same isotope are as far as we have been able to determine experimentally, exactly identical (same mass, same charge, same everything) - there isn't any "manufacturing variation" that we've been able to find.
I like that phrase "manufacturing variation".

I'll expand on your idea: I believe it is more than merely "variation that we've been able to find". I believe that it has been proven that - by definition - subatomic particles are identical. I'm not positive (heh) about the nucleus, but it is true about electrons. All electrons in the universe are interchangeable. (In fact, to take it to the extreme, it has been somewhat fancifully proposed that there IS only ONE electron in the entire universe, looping back and forth through time.)
 
  • #60
litlbunny said:
At what point does it make itself a moot point? (at first glance I thought your entire statement answered this question, but I need more clarification from you to try and see where you are going with this train of thought)?)
I'm second-guessing you. I'm heading off the potential line of thinking wherein you point to minor variations between the functioning of the clocks munging up the numbers demonstrating the theories. I am merely saying that you can do enough checking to ensure that there is no error creeping into the final answer due to deficiencies in the apparatus.


litlbunny said:
Would location within the universe be the main reason why there are discrepancy when it comes to clocking time more then any other variables? (Meaning if the Earth wasn’t there, yet the clocks remained in their physical location within the universe, would that be the main reason for the discrepancy if the experiment principles I used remained the same?)_
I wish to define "discrepancy" as "a devation from theorized, expected, calculated values". Any good theory will take all your factors into account, thus they will not be discrepancies. The discrepancies would be anything that the theory fails to explain.
 
  • #61
litlbunny said:
At what point does it make itself a moot point? (at first glance I thought your entire statement answered this question, but I need more clarification from you to try and see where you are going with this train of thought)?)
I'm second-guessing you. I'm heading off the potential line of thinking wherein you point to minor variations between the functioning of the clocks munging up the numbers demonstrating the theories. I am merely saying that you can do enough checking to ensure that there is no error creeping into the final answer due to deficiencies in the apparatus.


litlbunny said:
Would location within the universe be the main reason why there are discrepancy when it comes to clocking time more then any other variables? (Meaning if the Earth wasn’t there, yet the clocks remained in their physical location within the universe, would that be the main reason for the discrepancy if the experiment principles I used remained the same?)_
I wish to define "discrepancy" as "a devation from theorized, expected, calculated values". Any good theory will take all your factors into account, thus they will not be discrepancies. The discrepancies would be anything that the theory fails to explain.
 
  • #62
DaveC426913 said:
I like that phrase "manufacturing variation".

I'll expand on your idea: I believe it is more than merely "variation that we've been able to find". I believe that it has been proven that - by definition - subatomic particles are identical. I'm not positive (heh) about the nucleus, but it is true about electrons. All electrons in the universe are interchangeable. (In fact, to take it to the extreme, it has been somewhat fancifully proposed that there IS only ONE electron in the entire universe, looping back and forth through time.)

I tend to agree, actually, but it's probably safer to say that we haven't been able to find any variations than for the thread to get sidetracked on some philsophical disucssion of "how do we know for sure there aren't any differences between atoms".

Certainly, the quantum mechanical viewpoint is that all atoms of the same type are identical.
 
  • #63
Clocks (even atoms) do not travel at the "speed of light".

If you take a clock on a round trip at high velocities (such velocities will always be less than the speed of light!), it will not read the same as a clock that you left behind. We can see this most clearly with atomic clocks, but at high enough velocities, any-old kludgy clock would detect the difference, even a very primitive clock.
I agree with this statement 100%. But, that brings about another question. If velocity can affect the measurements of time shouldn't that same principal be observed if both clocks where traveling within the same ship, yet at two locations within that ship, if that ship was traveling at a high rate of speed? Meaning using your above statement that two separate clocks one in motion and one being left behind would show a variation, so one can theories, could they not, that the same principles would be observed if two clock traveled on the same ship but in two separate locations. Even after taking into account all the mechanical discrepancies that can be explained away?

Note that the lifetime of muons serves as a crude "clock" of sorts, and at the velocities that muons travel when they are generated in the upper atmosphere by incoming radiation, the change in lifetime is noticable by the very crude "average lifetime of a muon" clock. If it were not for relativistic effects, muons could never live long enough to reach the Earth's surface - but we observe that they do reach the Earth's surface.
Once again I agree, however, because muons are reaching the earth, can we then speculate they are reaching Mars and possibly all the way to Saturn and beyond? If so, are we then saying it is simply because muons have "collided" with the Earth that is why they have come out of their relative state? And if that is true, are we then saying they would stay within that state forever if they never come into contact with a solid body? And if that is true, then how does relativity account for something that stays within that state forever? Is relativity just another level of the universe, in and of itself, in which something can last forever in? Or, is there something else happening we cannot explain yet?
 
  • #64
I'm second-guessing you. I'm heading off the potential line of thinking wherein you point to minor variations between the functioning of the clocks munging up the numbers demonstrating the theories. I am merely saying that you can do enough checking to ensure that there is no error creeping into the final answer due to deficiencies in the apparatus.
Agreed, chances are good its not the mechanical apparatus itself causing the change in time. So, we are left with velocity in direct reaction to time that is causing the deficiencies, or could it be the measurement of time itself? Meaning, when we theorize about relativity, are we using the wrong formula to measure time?

Earlier I asked, "If both clocks (computerized) where set at absolute zero starting point at the same location within our galaxy separated by only a fraction of a inch, and one stayed absolutely still (did not move at all, no universal forces could move this clock) while the other traveled at the speed at which our galaxy rotates, yet both remained connected to the same power source (non solar) would their times still be the same or close to the same? Or would time change drastically between the two clocks?"

Wouldn't are measurement of time completely change within the stated parameters within this question? Meaning, would time be the same everywhere, or would time within our calculated measurements need to change everywhere we went?

Or would time be this question I asked earlier as well, "Okay, but time as the standard that is used in several theories, they use time within reference to this planet do they not? So I guess the question I will ask next of you is, would time still flow if we didn't use our standard understanding of it? And if the ticking of the universal clock where to continue ticking even if we are not using our own understanding of time, then how far does the universal time clock travel and does it encompass the entire universe simultaneously?"

After reading several theories that attempt to answer the question of time and relativity, those two question I just asked have perplexed me the most.
 
  • #65
litlbunny said:
I agree with this statement 100%. But, that brings about another question. If velocity can affect the measurements of time shouldn't that same principal be observed if both clocks where traveling within the same ship, yet at two locations within that ship, if that ship was traveling at a high rate of speed?

I think you may be misunderstanding time dilation. The people on the ship see their own clocks as running normal, and themselves as stationary.

It is only the people who are watching the ship move who also see the ship's time apparently running in "slow motion".

This is assuming that the ship is not accelerating and simply moving at a high speed - there are some additional possibility for more and different sorts of confusion if the ship is accelerating.

Once again I agree, however, because muons are reaching the earth, can we then speculate they are reaching Mars and possibly all the way to Saturn and beyond? I

The muons are being generated by high energy cosmic rays in the upper atmosphere. They are not traveling millions of miles because, even with relativistic time dilation, they can't travel that far.

See for instance http://einstein.byu.edu/~masong/HTMstuff/C9Q1.html

Besides these cosmic ray generated muons, there are experiments where the lifetimes of artifically generated and stored muons in storage rings have been measured. Those muons are also seen to live longer when they are moving quickly. The sci.physics.faq on the experimental basis of relativity gives such "particle lifetime" tests for not only muons, but other short lived particles as well (pions, mesons, and kaons).

http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html
 
  • #66
Besides these cosmic ray generated muons, there are experiments where the lifetimes of artifically generated and stored muons in storage rings have been measured. Those muons are also seen to live longer when they are moving quickly. The sci.physics.faq on the experimental basis of relativity gives such "particle lifetime" tests for not only muons, but other short lived particles as well (pions, mesons, and kaons).
wow man, that's amazing
 
  • #67
pervect said:
The sci.physics.faq on the experimental basis of relativity gives such "particle lifetime" tests for not only muons, but other short lived particles as well (pions, mesons, and kaons).

http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html

You'll notice that the references for particle lifetime tests peter out in the 1960s. That's because particle physicists take time dilation for granted and routinely incorporate it into analysis of their experiments where necessary.

When I was a grad student in the late 1970s and early 1980s, one of the things I did was study [itex]K^0[/itex] and [itex]\Lambda^0[/itex] produced in neutrino interactions in a bubble chamber. I had to take time dilation into account, in analyzing the paths of the particles involved.

One of my friends worked on an experiment that studied (I think) [itex]\Sigma[/itex] and [itex]\Xi[/itex] hyperons. If it had not been for time dilation, they would not have been able to produce a usable beam of them... they would have decayed so quickly that the beam would have been only a few millimeters long. Instead, the beam extended several meters, long enough to build a decent detector around.
 
  • #68
I think you may be misunderstanding time dilation. The people on the ship see their own clocks as running normal, and themselves as stationary.

It is only the people who are watching the ship move who also see the ship's time apparently running in "slow motion".

This is assuming that the ship is not accelerating and simply moving at a high speed - there are some additional possibility for more and different sorts of confusion if the ship is accelerating.
Actually I think you misunderstood my question. And I apologize for that. Remember that question was talking about a high rate of speed, yet I was going off the premises one would remember that I specifically asked in this previous question, "what would the effect be if one person was standing on top of that first clock and another was standing on top of the second clock while both persons where inside that same ship, (*separated by the length of the ship) at both the startup and stopping points while traveling at the speed of light?" One could theorize could they not, that velocity could create relativity principles to one part of a ship while leaving the other part of that same ship alone?

(*)added from a previous question.
 
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  • #69
The muons are being generated by high energy cosmic rays in the upper atmosphere. They are not traveling millions of miles because, even with relativistic time dilation, they can't travel that far.

See for instance http://einstein.byu.edu/~masong/HTMstuff/C9Q1.html

Besides these cosmic ray generated muons, there are experiments where the lifetimes of artifically generated and stored muons in storage rings have been measured. Those muons are also seen to live longer when they are moving quickly. The sci.physics.faq on the experimental basis of relativity gives such "particle lifetime" tests for not only muons, but other short lived particles as well (pions, mesons, and kaons).
I stand corrected, I was taking into account other possibilities with regards to muons and how they where mentioned within this concept of time. (muons as we have measured them, have a life span of 2 microseconds, yet travel farther then the speed of light would allow.) However, my point still stands, regarding if they are happening on Mars and Saturn? And if so, would their life spans increase or decrease because of the different atmospheres/pressures that exist within those two planets? And if their life span does increase/decrease, (or put another way travel greater or shorter distances) what does that mean to our understanding of relativity in connection to how it was mentioned here? Nothing?
 
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  • #70
The muons, pions, etc. that we produce at particle accelerators usually travel through evacuated pipes, sometimes through detector material such as liquid hydrogen (in bubble chambers) or various combinations of metal, plastic, etc. (in electronic detectors). As far as I know, the material the particles travel through has no effect on their decay lifetime except insofar as it reduces their speed.

So I would not expect any difference due to different atmospheric conditions on the Earth, Mars, etc.
 

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