How accurate are atomic clocks??

Aha!

Hi overdoze,

"Well, I was deliberately trying to avoid saying "ether", just because it gives a false impression. I'm not trying to talk about an ideal gas that permeats the universe (which is what ether is, classically.)"

Ideal gas ? What has matter got to do with aether ? The aether is the "medium" through which electromagnetic waves propagate (well, that's what the common believe was until somewhere around 1905-1910). It is not matter-based at all.

"Well, I am just not satisfied with models that define light as a wave but refuse to postulate a medium in which the wave arises and travels in the first place."

Looks like you are ready for some quantum mechanics then, were ordinary matter is given a wave character too

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... After that you'll see that the current theoretical believe is that all matter and light have a wave-particle duality that "live" in spacetime. (Sidenote: I say "current", I should rather say: somewhere around the 1970's, in the meanwhile string theory has popped up and is gaining popularity, even though I think the majority of the scientific community is rather sceptic against it).

Bye!

Crisp

 

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Overdoze,

First, I'd like to say that your post was enlightening. I'll read it a few more times so that I can fully understand its value. If I'm correct, you may have brought relativity to it's knees.

Next, I'd like to say that I believe that a device can be built that would measure the one-way speed of light in a moving frame of reference. This is how it would work:

You have two stationairy clocks on a platform. The clocks are 1 meter apart. One clock has a laser and the other clock has a detector. The clocks DO NOT have to be synchronized.

While at rest (relative to the Earth), the first clock fires a laser pulse towards the second clock. The first clock records the time when the laser is fired (t1), in its own time. When the laser pulse hits the target, the second clock records the time in it's own time (t2).

After t1 and t2 are obtained, the platform, with both clocks, is accelerated to a certain speed (relative to the Earth). When the speed is reached, the first clock fires a laser pulse towards the second clock. The first clock records the time when the laser pulse is fired, in it's own time (t3). When the pulse hits the target, the second clock records the time in it's own time (t4).

Conclusion:

In this example, since both clocks are in the same frame of reference, time dilation and length contraction(if they exist) do not have to be taken into consideration.

Therefore, if the speed of the laser pulse is the same in both cases then:

t1-t2=t3-t4

However, if t1-t2 does not equal t3-t4 then the difference in time between the two can be used to calculate the absolute speeds of the two clocks, and of the Earth (of course to calculate the total velocity, six clocks would have to be used).

Also, if it was found that the speed of light in a moving frame of reference is dependent on the speed of the frame of reference relative to the absolute frame of reference, relativity is in serious trouble.

Tom

 

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Crisp,

I see we're getting a little off-track here, so I probably won't argue along this direction much longer. But just to clarify my position:

Classically, aether was modelled as an ideal gas that filled the universe. That's the reason why Maxwell's original electromagnetic equations are full of concepts such as flow and flux. People thought this "gas" was stationary in an absolute sense, so moving through it would produce detectable effects -- which, of course, failed to be detected (e.g. Michelson-Morley.) Following which, it was concluded that there is no aether at all -- which IMHO is throwing the baby out with the bathwater. Rather, I think the situation is that "aether" is real but it's not a gas of some sort with respect to which you can move. Rather, it is a medium from which light and matter and everything else arises (kind of like the ocean, with everything we know being just waves on the ocean's surface.) If you want to think of moving through aether, the more proper analogy would be a soundwave "moving" through a medium. Yes, you may indeed be moving with respect to the fundamental texture of the medium, but you are an emergent phenomenon on top of that medium, and you can't directly interact with it to even so much as perceive it (no more than a sound wave can interact with air to determine its velocity with respect to the average velocity of molecues in the air.) You can't see the medium; you just presume its existence based on your own existence and features thereof.

Tom,

Thank you, I'm flattered

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However, I would prefer to think that I didn't bring relativity to its knees. On the contrary, I think I've shown where it comes from and why it is valid. And Einstein is still my hero

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Great minds think alike, eh?

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I remember my own struggles with relativity, and I've gone through exactly the same thing you're going through right now. A physics "puberty" of sorts; anyone with any genuine interest in relativity pays this price. But once you do get to the other side, there's no regrets because the clarity is awesome. So a fair warning and an encouragement: don't despair no matter what

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Astonishingly enough, this is almost exactly my own line of thought a few years back. Just one of those many little thought experiments I’ve struggled with.

This is where your (and mine, previously) subtle mistake lies. Time dilation and length contraction do play a role. Since you are accelerating both clocks identically, they can be considered to be in a special reference frame of their own. Remember that in all moving FORs the length is shrunk along direction of motion. That means that while you think you’ve accelerated both clocks equally, the actual distance between then has shrunk. Additionally, this means one of the clocks has traveled a slightly longer distance in process of acceleration, meaning at some point its speed was greater than the other clock’s and its time a little more slowed down. It turns out these seemingly minor effects grow in exact correspondence with the added differential between the speed of the clocks and the speed of the propagating light front – thereby precisely canceling out.

It won’t affect relativity really all that much. What it will do, is confirm my analysis and generate a more encompassing perspective where relativity would be just a special case – in a manner similar to how Newtonian physics is a special case of relativistic physics.

But personally, so far I have not been able to come up with a method to do what you're trying to do, that would stand up to scrutiny.

 

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James R,

I find interesting your religious belief that relativity must be correct. Your closed-mindedness goes against the core of what science stands for.

Your closed-mindedness is preventing you from learning. I hope one day you get over YOUR problem.

I bet all of you are wondering why I'm so much against relativity. The reason is is that I believe that the whole universe is built from quantums of space, energy, matter, and time. Einstein's theories claim that you can have fractions of "quantas" at relativistic speeds. These "fractions" go against the concept of quantum physics.

Tom

 

Overdoze,

Your entire post, including your formulas for length contraction and time dilation, is based on the assumption that the omnidirectional speed of light is c in all frames of reference.

However, if you assume that there is an absolute frame of reference, and that the omnidirectional speed of light is only c in the absolute frame of reference, then time dilation and length contraction DO NOT exist.

The time dilation and length contraction percieved by the moving observer is the result of an illusion caused by the increase or decrease in the speed of electromagnetic radiation, for the observer, that the observer uses to measure time and distance.

In other words, this means that relativity is wrong.

Please correct me if my conclusions are incorrect.

Tom

 

Hi Tom,

"I bet all of you are wondering why I'm so much against relativity. The reason is is that I believe that the whole universe is built from quantums of space, energy, matter, and time. Einstein's theories claim that you can have fractions of "quantas" at relativistic speeds. These "fractions" go against the concept of quantum physics."

Well, I am sorry to tell you this but this makes no sense. Quantum physics tells nothing about the structure of spacetime, the "quanta" refer to the minimal packets of energy exchange, charge, momentum, angular momentum, ... Quantum physics prohibits the use of "fractions" of quanta.

Special relativity does not describe smaller items than eg. energy quanta (photons) going at relativistic speeds. As a matter of fact, quantum physics and (special) relativity work well in what is called quantum field theory, i.e. they are compatible and a theory that takes both into account already exists.

Considering the unification of gravity (general relativity) and quantum physics: I think a Nobel prize is waiting for the person who can accomplish that. If you can work out your theory of quantum spacetime, make it consistent, explain previously unexplained effects, or at least produce some results with it, then please feel free to share those thoughts with us. Until then, I am afraid it is nothing more but speculation. Interesting speculation though

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.

"However, if you assume that there is an absolute frame of reference, and that the omnidirectional speed of light is only c in the absolute frame of reference, then time dilation and length contraction DO NOT exist."

Hrmmm... Have you proven this somewhere ?

"The time dilation and length contraction percieved by the moving observer is the result of an illusion caused by the increase or decrease in the speed of electromagnetic radiation, for the observer, that the observer uses to measure time and distance. In other words, this means that relativity is wrong."

There is more to it. As James R said, "even when compensating for the finite transmission speeds of information, i.e. the speed of light, the effects of time dilatation and length contraction still remain".

Now you keep on claiming that relativity is "wrong". You can't claim that, since that would require:
a) an inconsistency in the theory of relativity. So far none has been discovered (yes, we had troubles replying to some of your problems, but in the end they worked out)
b) a better alternative that explains reality in a better way.

You claim that relativity is wrong based on "logic" and the claim that time dilatation is merely an illusion. I have no problem with that, but if you want to convince some people, then I suggest you explain... hrmm... for example why elementary particles can live longer than they should when going at relativistic speeds. You can use your absolute frame of reference, but you are not allowed to use time dilatation and length contraction formulas since those are concepts from the theory of relativity.

Bye!

Crisp

 

Crisp,

You didn't understand what I was saying. The more we know about the universe, the more we find that things are composed of quanta. Physicists have so far found that energy and charge are "quantumized", but it is very likely that scientists will find that everything in the universe is "quantumized", including time and distance.

If time and distance are "quantumized", then Einstein's formulas for time dilation and length contraction would give fractions of time and distance. This would be contrary to quantum physics.

Yes I did. If you recall the example with the observer and his flashlight.

If you recall, you and James came to the illogical conclusion that there is a seperate time dilation for each beam of light in order to preserve Einstein's assumption of the invariance of light.

I have to say, you really disappointed me. I was expecting James to choose Einstein over logic, but I wasn't expecting you to do the same.

Did you ever think about what you and James were claiming, instead of blindly following the formulas in your textbook??

C'mon try to. Close your eyes and imagine it. You will also find it illogical.

I'll have to think about that. The thing that bothers me the most is that it is so hard to find "raw data" from experiments. It's easy to find theories, but the data that was used to derive the theories is absent. Example: If physicists found that some unstable particles DO NOT live longer at relativistic speeds, would we ever here of it?? Or would they assume that it's a flaw in their readings?

Note: Since the speed of electromagnetic radiation is affected by the speed of a frame of reference, perhaps this may also prevent an unstable particle travelling at relativistic speeds from decaying when it should.

Tom

 

Hi Tom,

"If time and distance are "quantumized", then Einstein's formulas for time dilation and length contraction would give fractions of time and distance. This would be contrary to quantum physics."

As James R pointed out, special relativity is not a quantum theory and hence incompatible. However, they can be made compatible (as I said in my previous post, using quantum field theory). So if further quantisations can be found, there probably will also be a new theory that is relativistically invariant.

"If you recall, you and James came to the illogical conclusion that there is a seperate time dilation for each beam of light in order to preserve Einstein's assumption of the invariance of light."

Correction: that is what you made of it

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. And also, there are no attempts to "presever the invariance of the speed of light": this is automatically taken care of.

"I have to say, you really disappointed me. I was expecting James to choose Einstein over logic, but I wasn't expecting you to do the same."

There is a *huge* difference between logic and daily intuition, which I think you are confusing with logic. The theory of relativity is a good one, I like it a lot since it is the first major advancement over Newtonian mechanics that still has more or less the same structure. One of the cute things of SR is that it is logically consistent, but counterintuitive things are derived from its postulates. That does not make the theory illogical, just harder to get a grip of.

I've already advised it, but you should really pick up a textbook on relativity if you want to go deeper into it. Logical deductions in words simply won't do the job in physics, logical math is also required.

"Did you ever think about what you and James were claiming, instead of blindly following the formulas in your textbook??"

Hrm... I am actually wondering whether I should question the mind's capability to grasp counterintuitive things and just rely on the math. But then again, I still have to meet the first person that purely on reason (and without math) can answer the question "if I am going at nearly lightspeed and I turn out my car's headlights...". Believe me, I sometimes wish that physics could also be done without the math

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... things don't just always go the way you want.

IMHO, what should be thought about are the postulates, the rest is math. You don't want to question math, do you ? As far as the interpretation of the results is concerned, I can only say: illogical does not necessarily mean not true. However, since we assume math is consistent, and that we accept the postulates, then all results are correct within that framework. From the moment you step out of that framework (eg. you throw away the constancy of the speed of light for all frames of reference like you do), you are no longer allowed to work in that framework. Hence, as a convinced pro-relativity person, I accept the results, even when they seem illogical. There is not really much to think about (though I should note that eg. the "shut up and calculate" quantum mechanical approach is also not what I am referring to).

Bye!

Crisp

 

Crisp and James,

Quote from James:

Quote from Crisp:

Ok. Let's see what both of you said.

First James:

Finally, Crisp's response:

In other words, the two of you believe that the moving observer experiences two time dilations, one for each beam of light. As James put it t=0.229 seconds AND t=4.35 seconds at the same time.

However, if you extend your reasoning then almost every photon of light coming from the observers flashlight has its own time dilation. I'm really surprised that the two of you can even consider that the observer observers more than one time dilation at the same time. What puzzles me even more is that the two of you believe that time speeds up for the observer, depending on which way he is pointing his flashlight.

If I recall correctly, Einstein claimed that time slows down for the observer, it doesn't speed up.

If I misunderstood the two of you somehow, please enlighten me.

James R,

I never claimed that light travels at c in all frames of reference. You mentioned this for the second time in your last post, and I really don't know what you are referring to. I have always claimed that light doesn't travel at c in a moving frame of reference, and I tried to illustrate this in my example (the observer and his flashlight). Maybe you have me confused with someone else.

Crisp and James,

I see that the two of you don't respect logic(or you respect it until it gets in the way of relativity).

I've concluded that no matter what logical proof I provide that Einstein is wrong, I will never be able to change your minds. The fact is that we have different priorities: The two of you place theories above logic, while I place logic over any theory.

As long as the two of you practice this "philosophy", our discussions on sciforums will never be resolved.

Tom

 

Ah, but...

Hi Tom,

"In other words, the two of you believe that the moving observer experiences two time dilations, one for each beam of light. As James put it t=0.229 seconds AND t=4.35 seconds at the same time."

Ah, an unfortunate misunderstanding from my side of what you meant by "time dilatation". Usually the "time dilatation" factor is referred to as the value of <font face="symbol">g</font>, and this is ofcourse the same in both situations. As a matter of fact, from the moment you know an observers speed relative to what is considered to be a stationary observer, <font face="symbol">g</font> is known and remains the same.

But more to the point: the reason why the two times are different. I'm having some trouble putting it to words at the moment, I'll think about it and get back later today/tomorrow. I'm gonna work out a slightly different situation first for comparison.

Bye!

Crisp

 

Hi Tom,

Quick question, I have some ideas on how to explain why the two times are different, but will you accept an answer where the speed of light is assumed to be invariant for all observers ?

Bye!

Crisp

 

Crisp,

I can't. This whole discussion on this thread is about questioning the validity of the principle of invariance of light. I used the example of the moving observer with the flashlight as proof that it can't be correct. If I were to assume that it is correct, then there would be nothing to argue about.

Therefore, I can only accept an explanation that proves that the principle of invariance of light is correct, using only the length contraction and time dilation formulas.

And, by the way, prove it in a way where the moving observer experiences only one time dilation.

Tom

 

Hi Tom,

"Therefore, I can only accept an explanation that proves that the principle of invariance of light is correct, using only the length contraction and time dilation formulas."

I am afraid that this is not possible (at least not in the way you want to hear it). The classical time and length dilatation formula's are only correct under certain circumstances (eg for time dilatation this would mean that the two events that mark the time interval have to occur at x' = 0, i.e. in the origin of the moving observer). Hence if we would want to use that formula, we would need to bounce the lightbeam of a mirror to get it back at the moving observer's origin. Unfortunately, you will then argue that some "averaging" out occurs, and hence the discussion will not be settled.

But once again, you can object all you want, from relativity - if properly applied - you will always get that the speed of light is c for all observers. It is a postulate in the theory, everything is built on top of that. And because of mathematical consistency, this result will pop back out every time you calculate it. At this point I actually wonder why we are still debating the invariance of the speed of light, the only thing that can say something about it is the experiment, and those are in favor of the invariant lightspeed position (i.e. the relativist position). It has already been said, you cannot disprove a consistent theory from within its own framework.

"And, by the way, prove it in a way where the moving observer experiences only one time dilation."

There is only one time dilatation factor, however, different times/events transform in different ways.

Bye!

Crisp

 

Crisp and James,

Why don't the two of you face the fact that there is no solution for the example that I have given, where the light travels at c in both cases.

I'm still surprised by your belief that if the observer points his flashlight forward, for every stationairy second the observer experiences .229 seconds, but if the observer points his light behind him, then for every stationairy second, the observer experiences 4.35 seconds.

Obviously, the observer can't experience two time dilations at the same time, can he?? Why don't the two of you think about what you are saying???

The fact is that both of you can't accept that the speed of light in a moving frame of reference is only c if you reflect the light off a mirror, and then average the speed. The two of you assumed that Einstein is correct regarding the invariance of light, even though it hasn't been experimentally proven. Now, it turns out that it can't be mathematically proven either.

Well, I guess there's always faith.

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Tom

 

Hi Tom,

The difference in the two times can be nicely explained if you accept the invariance of the speed of light. This is not suprising since you indirectly use that same invariance in the Lorentz transformations.

Also, we are talking about two different events here (flashlight shining forward/backward). James R already noted that the notion of simultanity if not necessarily preserved when transforming from one observer to another. Hence, for the stationary observer, the two flashlights might simultaniously hit -300.000 km and +300.000 km after one second, this does not necessarily mean that for the moving observer they do.

The times we (or rather: James, but I completely agree with his calculations) calculated denote the time required for the MOVING observer to reach the two points established above (respectivily -300.000 km and +300.000km for the stationary observer). As the concept of simultanity is no longer necessarily valid, the times for the moving observer can differ. This seems to be the case here (note that we're talking about an extremely extraordinary problem here, observers at 0.9c are not really everyday stuff

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).

That kinda solves the time difference debate I think...

Bye!

Crisp

 

Crisp,

I'm sorry I can never accept your explanation. The observer has only one clock. For every stationairy second, x seconds passes for the moving observer.

x can't be equal to 0.229 and 4.35 seconds at the same time. The observer's clock can't indicate that 0.229 seconds and 4.35 seconds passed at the same time. It is an impossibility. The moving observer's clock can only indicate ONE time.

How can you or James possibly prove, using atomic clocks, that 1 stationairy second can equal both 0.229 and 4.35 seconds for the observer?? Where would you place the clocks to prove this??You can't move them with the light, because then they would not be in the observer's frame of reference. If you put both clocks next to the observer, you will find that they will both have the same time.

Tom