Special Relativity

[Dragar]

If the speed of light is (measured to be) constant in all inertial frames, either:

1. Special relativity holds in all inertial frames
2. The laws of physics are different in different frames.

The Gregorian is holding to the second premise; this is a ridiculous notion but logically consistent.

 

[Joe_Sixpack]

It's possible that a moving particle simply decays slower when in motion, IAW the formula presented by SR... a slower decay rate instead of a constant rate through altered flows of time.

Again... the numbers are observable, but the explanation of those numbers aren't proven by the numbers themselves.

i.e. 1 apple+ 1 apple=2 charles mansons.

Yes, 1+1=2... no, the explanation is not right.

Yeah, perhaps (though that would throw off a whole lot of other physics which are really really supported as well - again, like Quantum Mechanics), but your ad hoc explanation would have to explain why cesium clocks and in fact all other clocks, whether atomic or not, moved slower exactly the same and all in inverse proportion to SQRT(1-v^2/c^2). Sorry, but your explanation doesn't hold much water.

Another thing is that you would have to explain how a cesium clock even knows it is moving - i.e. motion is always relative and everything is always moving relative to something else. Why even say that the clock in the plane is moving? The Earth could just as easily be said to be moving beneath it in the opposite direction. The rules of physics MUST be the same in all non-accelerating (inertial) reference frames or things would get really wacky.

 

[The Gregorian]

One, muons are not atoms, and two, you are compounding your problems by throwing out all sorts of other highly supported physics like the Standard Model.

You really need to go back to original formulation of Relativity. SR only uses two postulates to get to its core conclusions: 1) the laws of physics are the same in all inertial reference frames, and 2) speed of light is constant in free space (shown conclusively about 25 years earlier than Einstein my Michelson - light never travels at c+v or c-v in same medium, it always travels at c). Using just these postulates you can show how time must different in different reference frames (try visualizing the simplest clock: a photon emitter and a sensor plate).

Exactly my problem with SR... It bases everything on those two postulates... while throwing both postulates out the window at the same time.

Yes, all laws apply equally to any non-accelerating body. No problem there... yet the train example states that if you don't DETECT two things happening at the same time, they must not have. If our sun and the next closest star each turn bright pink simultaneously... we'll find out about our sun much quicker... The fact that we don't realize it doesn't mean it didn't really happen.

If it turns bright pink now, the world won't know for 8 minutes (I believe that's the right figure?). If during those 8 minutes, I travel one light-minute away... I'll find out one minute later! That's not changing time... that's changing distance. Whether I traveled one light-minute away in the span of those 9 minutes, or if I'd been moving for the last 1,000 years, or if I teleported instantly... changing the distance anything has to travel changes the amount of time it takes to travel that distance (assuming a constant speed).

Secondly, the experiments you value so much that measure light do so by bouncing light off mirrors stationary relative to eachother... No one's saying light doesn't have a constant speed relative to it's source... but every time it hits something and is re-emitted, it goes at it's speed relative to what it bounced off last. Move whatever mirrors whatever speed you like... as soon as it bounces off the first one, you've ruined the experiment. That's your fundamental problem.

It's easily observable that light does not travel at the same speed in all frames of reference due to the dopplar effect. One ray of light will have different frequencies depending on your speed relative to it... Unless you think the light "senses" this and changes it's wavelength depending on the relative speed of each object in the universe observing it... you have to admit the only other way to change frequency is by changing the speed of the wave.

Unless you believe the same photon will have different wavelengths for each of the infinite other possible frames of reference in the universe.

 

[sinan90]

That's all fine and dandy if the laws of the universe followed "common sense", but it doesn't so what seems reasonable in normal everyday situations doesn't apply in extreme situations.

http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html

There's a whole list of experiments to disagree with too if you'd like.

 

[Joe_Sixpack]

Exactly my problem with SR... It bases everything on those two postulates... while throwing both postulates out the window at the same time.

Yes, all laws apply equally to any non-accelerating body. No problem there... yet the train example states that if you don't DETECT two things happening at the same time, they must not have. If our sun and the next closest star each turn bright pink simultaneously... we'll find out about our sun much quicker... The fact that we don't realize it doesn't mean it didn't really happen.

If it turns bright pink now, the world won't know for 8 minutes (I believe that's the right figure?). If during those 8 minutes, I travel one light-minute away... I'll find out one minute later! That's not changing time... that's changing distance. Whether I traveled one light-minute away in the span of those 9 minutes, or if I'd been moving for the last 1,000 years, or if I teleported instantly... changing the distance anything has to travel changes the amount of time it takes to travel that distance (assuming a constant speed).

Secondly, the experiments you value so much that measure light do so by bouncing light off mirrors stationary relative to eachother... No one's saying light doesn't have a constant speed relative to it's source... but every time it hits something and is re-emitted, it goes at it's speed relative to what it bounced off last. Move whatever mirrors whatever speed you like... as soon as it bounces off the first one, you've ruined the experiment. That's your fundamental problem.

It's easily observable that light does not travel at the same speed in all frames of reference due to the dopplar effect. One ray of light will have different frequencies depending on your speed relative to it... Unless you think the light "senses" this and changes it's wavelength depending on the relative speed of each object in the universe observing it... you have to admit the only other way to change frequency is by changing the speed of the wave.

Unless you believe the same photon will have different wavelengths for each of the infinite other possible frames of reference in the universe.

Think you need to go back to Michelson-Moreley. Hate to break it to you, but c is not different depended upon your relative speed - there are an extremely large number of experiments that confirm this.

Also, try looking up the concept of symmetry. If the simplest clock changes depending upon relative speed of the observer (i.e. the photon moving from an emitter to a sensor some distance away), all clocks change.

Again , I challenge you to go back to the original derivation. It is not that complicated and there are many physics books that walk through Einstein's thought process. If you throw out SR you would have to throw out a extrordinarily large amount of related physics that have a huge amount of experiemntal backing as well. Face it - SR is extremely successful as an explanation and is one of the most experimentally verified theories in all of science (due to measurement advantages, Quantum Field Theory is actually the current record holder for predictive accuracy at 15 or so significant figures, but SR is very close).

This conversation is reminding me why I decided years ago not to get into an argument with any one of the thousands of Internet cranks saying that they can prove Einstein was wrong. Funny, how they can't get a single physicist to agree with them...

 

[The Gregorian]

Step back for a second. Cosmic rays were first discovered in 1912. This particular property of cosmic rays is exactly predicted by special relativity, which was proposed in 1905. There are no free parameters here that can be fudged by experiment. Special relativity gives an exact prediction on the relative abundances of muons at high and low altitudes that is dependent upon the energies and the measured rest-frame decay time of said muons.

1 apple+1 apple=2 charles mansons. Just because the math works doesn't make your explanation for that math infallible. Yes, the numbers predicted the effects of moving decaying material... Does this mean decaying material decays more slowly while in motion, or that it ALWAYS decays at the same rate, but time itself bends?

Now... if WE see those particles traveling at nearly the speed of light... yet we know that each particle is experiencing time at 1/20th of our rate, what are we to say of it? All parties agree on the DISTANCE it traveled... but it traveled the same distance in 1/20th of the time we experienced, while WE clock it at nearly the speed of light? Equal distance in 1/20th the time=that particle's frame of reference puts it as going 20x as fast as what we see (nearly the speed of light).

Of course, I pulled "1/20th" out of a hat... but I'm sure you get the idea. Whether it's really 5% of our perception of time or 1%, you only change the factor by which to multiply our perceived speed to deduce it's perceived speed.

... you can't balance "going faster" with "slowing time" ... because that creates a paradox... the same distance is covered during a shorter period of perceived time, increasing perceived speed... slowing time more... increasing perceived speed... slowing time more. etc.

And you think that making up an entirely new physical process is a simpler explanation? Come on! How else could this prediction have come true if special relativity weren't rather accurate?

Numbers were fine, or close enough to account for an acceptable margin of error.... The numbers don't give the mathmetician free reign to plug whatever reasoning he wants into those numbers... i.e. 1 apple+1 apple=2 charles mansons. Likewise... yes, decaying material decays slower... possibly because it just decays slower while moving rather than time itself being manipulated.

Remember, all things are relative... If you experience time based on your speed relative to the earth.... what if you travel between the earth and the son? Do you experience time based on your speed relative to one celestial body over another? Do all of us simultaneously experience time at different rates relative to all bodies in the universe, or indeed all other theoretical points of reference throughout the universe?

Again... remember all things are relative... We think time stops for a beam of light traveling toward us because it's moving relative to us... but relative to all photons, they are standing still experiencing time normally, while all other matter in the universe is moving at the speed of light relative to each photon.... and because EVERYTHING else is moving at exactly C relative to each other beam of light, time stops for everything else in the universe... so who's correct?

Based on SR, neither are incorrect... so time is stopped for every photon AND everything EXCEPT each photon...


... either that or there isn't a universal constant/limitation.

 

[The Gregorian]

Again, you're confusing yourself. Photons can't "see" anything at all, because they're moving at the speed of light. Everything that happens from the time they're emitted to the time they're observed happens instantaneously as far as the photon is concerned.

Exactly my point. A photon experiences no time between when it's emitted and when it hits something... but it still moves... It travels... say... one light year... in what it perceives to be a single instant in time.

If it travels any distance (especially a large one), in an infinitely small period of time (because it's stopped)... it's traveled at an infinite speed... since speed is distance traveled in a period of time. If either variable is infinite, than the speed is infinite... which is faster than the speed of light.... which is not infinite.

See where that's going? Therefore saying that time "slows down" for things moving fast requires that those things think they're really moving faster. Time would have to speed up for things to remain within the speed limit...

Your muons actually suggest the exact opposite of time dilation.

 

[Joe_Sixpack]

Remember, all things are relative... If you experience time based on your speed relative to the earth.... what if you travel between the earth and the son? Do you experience time based on your speed relative to one celestial body over another? Do all of us simultaneously experience time at different rates relative to all bodies in the universe, or indeed all other theoretical points of reference throughout the universe?

YES!!!! Time is experienced differently at all valid reference points. At a steeper point of curve in a gravity well as well as from relative velocity.

Again... remember all things are relative... We think time stops for a beam of light traveling toward us because it's moving relative to us... but relative to all photons, they are standing still experiencing time normally, while all other matter in the universe is moving at the speed of light relative to each photon.... and because EVERYTHING else is moving at exactly C relative to each other beam of light, time stops for everything else in the universe... so who's correct?

No one's time is any more correct than anyone else's - there is no "universal clock."

For some stupid reason I am not following my own advice. I will leave now - believe whatever you wish to believe. Give some guys in Sweden a call, I am sure they want to get your Nobel Prize ready...

 

[BrainHertz]

Secondly, the experiments you value so much that measure light do so by bouncing light off mirrors stationary relative to eachother... No one's saying light doesn't have a constant speed relative to it's source... but every time it hits something and is re-emitted, it goes at it's speed relative to what it bounced off last. Move whatever mirrors whatever speed you like... as soon as it bounces off the first one, you've ruined the experiment. That's your fundamental problem.

This is not a new idea. What you're talking about was previously known as Ritz' emission theory, and has long since been discarded due to failure to agree with experimental data. One particular problem is that of eclipsing binary stars, and the order in which we would expect to see events if the speed of light is modified by that of the emitter. See also Ives-Stilwell experiment.

It's easily observable that light does not travel at the same speed in all frames of reference due to the dopplar effect. One ray of light will have different frequencies depending on your speed relative to it... Unless you think the light "senses" this and changes it's wavelength depending on the relative speed of each object in the universe observing it... you have to admit the only other way to change frequency is by changing the speed of the wave.

This is not an observation that light does not travel at the same speed in all frames of reference. And no, I do not have to admit that the only way to change frequency is to change the speed of the wave. I can change the wavelength at a constant velocity also.

Unless you believe the same photon will have different wavelengths for each of the infinite other possible frames of reference in the universe.

Yes. That's what SR says.

This is all very interesting and everything, and I'm happy to discuss as much as you want, but do you really think that you have found something that Einstein and everybody who has studied this problem in the last hundred years has somehow overlooked?

 

[The Gregorian]

Damn! I wish I had been checking this forum more often 'cause this is a subject I understand quite well, can elucide effectively (in my humble opinion) and people are screwing up their analysis all over the place...

Well, I appreciate the idea of someone actually explaining something rather than saying "You disagree with the textbook? Go back and read the textbook until you agree with it?"

If we can get past this subsection of discussion, it'll make the end discussion arrive sooner.

Slower decay rates are insufficient to explain the phenomena.

First, all actions are slowed down when their frame of reference is accelerated, not just atomic decay. That's why we say time, itself, has slowed. How else can you explain it?

Greater forces acting upon the particle. Of course wind resistance and whatnot isn't a factor here, but E=MC^2 admits that all matter is simply energy in another form... Unlikely static since everything tends to spin (from galaxies to atoms). Decay is basically part of a given chunk of material falling off... Think of a helicopter blade for a second. At a given engine RPM, the blade travels at the same speed regardless of the helicopter itself is stationary or moving relative to the earth... As the helicopter moves, forces act upon the rotor blades much differently because the advancing blade may be moving far faster than the retreating blade. Of course this example is flawed because the difference in forces for a helicopter is generally wind resistance, which doesn't exactly play a role in sub-atomic particals, but it is possible that there COULD be some force that is exerted differently when the particles stationary rotation is augmented by linear movement. Exactly what that is? I dunno... But it's more likely that there is some -force- acting upon the particle than time itself bending.

Again... if the particle knows it traveled the same distance in a fraction of the time, it must perceive it's going perportionally faster as it's time slows down (same distance in smaller time), increasing the issue of time dilation, does it not?

 

[The Gregorian]

Wavelength is the inverse of frequency. This incoherent ramble shows that you have no idea of the physics you are claiming is wrong. As I said before reality is indifferent to your inability to comprehend special relativity.

Exactly... what... I said? Frequency is based upon wavelength and the speed of each wave. Frequency can be changed by either changing the wavelength or the speed of the wave.

To say that light's frequency is observed to change via the doppler effect, but it's relative speed is ALWAYS the same indicates that the redshift/blueshift is a change in light's wavelength... But why would the form of the wave change depending upon the actions of an observer simply by observing it?

Namely... we can tell based on how frequencies of light is shifted, the speed toward or away from us the light's source is traveling.... If the speed of light is fixed, that means the wavelength varies depending on our speed relative to the light's source?


Meaning we can change the wavelength of light by moving relative to it...

Or... that we change the perceived frequency of light (like any other wave) not by changing the waveLENGTH, but by changing our speed relative to the wave, thereby changing the wave's relative speed.

Where do you see the problem? Other than "oh noz! that's not in my textbook."

 

[BrainHertz]

To say that light's frequency is observed to change via the doppler effect, but it's relative speed is ALWAYS the same indicates that the redshift/blueshift is a change in light's wavelength... But why would the form of the wave change depending upon the actions of an observer simply by observing it?

But you're assuming that there is some absolute frame of reference in which there is an "actual" value of wavelength. SR says that there is no such absolute, and different observers observe different things.

Namely... we can tell based on how frequencies of light is shifted, the speed toward or away from us the light's source is traveling.... If the speed of light is fixed, that means the wavelength varies depending on our speed relative to the light's source?

Yes.

Meaning we can change the wavelength of light by moving relative to it...

How do you mean, "change"? Again, there is no absolute value of length in the first place, just one measured in each of the reference frames we are interested in.

Or... that we change the perceived frequency of light (like any other wave) not by changing the waveLENGTH, but by changing our speed relative to the wave, thereby changing the wave's relative speed.

But that's not what we can observe happening.

Where do you see the problem? Other than "oh noz! that's not in my textbook."

I don't see a problem. And there's nothing new here.

 

[The Gregorian]

If the speed of light is (measured to be) constant in all inertial frames, either:

1. Special relativity holds in all inertial frames
2. The laws of physics are different in different frames.

The Gregorian is holding to the second premise; this is a ridiculous notion but logically consistent.

Depends on your idea of a constant. You believe light is a constant, and it's speed is a magical number all things are dependant upon.

I believe time is the closest thing to a constant that exists in the universe, only because time does not exist, cannot be altered... Things happen in a certain order... we sometimes perceive things out of order... we sometimes are delayed in detecting things... but this doesn't change the fact that at one instant in theoretical "time" ... the universe is one way... the next instant, the universe is another... it's not a fabric we tear through and can go back into... time is simply a theoretical way to explain how things were before they are, and how they will be later. Not something to be "slowed down" and sped up... simply flown through, never to return.

IMO, people may perceive time as "moving slower" but this is an illusion because time is, overall, an illusion. We are all ticking away... while it is this point in time for me, it is the same point in time for all others... in one second it will be one second later... regardless of how long or short that second SEEMS to take.


By this logic, the train experiment is perfectly logical.. it's an optical illusion. The flashes happened simultaneously regardless of how others observe it.

Better yet... two people take a picture with their flashes on simultaneously. Each person will detect the light from their flash slightly before the light from the other person's flash because the light from their flash was much closer... Even though BOTH see the other person's flash after their own... this doesn't mean time has slowed for each of them... only that they detected the closer image first.


Of course SR can't handle that experiment because it has the same effect as the train illustration without the train's motion relative to the poles. The same effect minus the motion factor invalidates motion as being the cause of that effect.

 

[The Gregorian]

last for tonight:

Think you need to go back to Michelson-Moreley. Hate to break it to you, but c is not different depended upon your relative speed - there are an extremely large number of experiments that confirm this.

Yes... M&M's experiment suggested that light is constant -relative to it's source-. No one's arguing that.

However, this certainly isn't evidence to support SR... in fact it's the opposite. If light is constant relative to it's source (A), all other things (B) moving relative to the source (A) must not be moving the same speed relative to light (C) as the source (A) they are moving relative to.

in other words, M&M proved that regardless of any observer's motion relative to the light source, light moves at the same speed relative to that source... showing that light DOESN'T move at a constant speed depending upon the observer... but upon the source.

... which is supported by observing the doppler effect.

 

[BrainHertz]

Depends on your idea of a constant. You believe light is a constant, and it's speed is a magical number all things are dependant upon.

That depends on what you mean by "believe". There's some evidence involved here, which you seem to be studiously ignoring.

I believe time is the closest thing to a constant that exists in the universe, only because time does not exist, cannot be altered... Things happen in a certain order... we sometimes perceive things out of order... we sometimes are delayed in detecting things... but this doesn't change the fact that at one instant in theoretical "time" ... the universe is one way... the next instant, the universe is another... it's not a fabric we tear through and can go back into... time is simply a theoretical way to explain how things were before they are, and how they will be later. Not something to be "slowed down" and sped up... simply flown through, never to return.

That's very nice for you that you believe that. It's the way things appear to work at everyday velocities and dimensions. If that's as far as you want to go, so be it.

As many people have patiently tried to explain, however, such everyday experiences do not correspond to observations in certain extreme cases. But go ahead and jam your fingers in your ears if you want.

 

[The Gregorian]

sorry... one more, then sleepy time for me... worked a 13+ hour day today and have work in 7 hours now....

But you're assuming that there is some absolute frame of reference in which there is an "actual" value of wavelength. SR says that there is no such absolute, and different observers observe different things.

So time is dictated relative to your speed... and length is dictated relative to your speed?

Yes?

This means both time AND space is dictated by your speed... which is defined as motion through space in a given time...

So time and space are dictated by speed which is defined by time and space, which is dictated by speed, which is defined by time and space, which is dictated by speed, which is defined by time and space, which is dictated by speed, which is defined by time and space, which is dictated by speed, which is defined by time and space, which is dictated by... uhhh....

anyone know what "circular reasoning" is?

 

[BrainHertz]

sorry... one more, then sleepy time for me... worked a 13+ hour day today and have work in 7 hours now....



So time is dictated relative to your speed... and length is dictated relative to your speed?

Yes?

This means both time AND space is dictated by your speed... which is defined as motion through space in a given time...

So time and space are dictated by speed which are defined by time and space which is dictated by speed which are defined by time and space which is dictated by speed which are defined by time and space which is dictated by speed which are defined by time and space which is dictated by speed which are defined by time and space which is dictated by speed.

anyone know what "circular reasoning" is?

There is no circular reasoning here. Both time and space are transformed according to the frame of reference. Do you need me to quote the actual derivation or something?

 

[Chalnoth]

Yes, all laws apply equally to any non-accelerating body. No problem there... yet the train example states that if you don't DETECT two things happening at the same time, they must not have.

You have misunderstood the train example. Again, see my post #9:
http://christianforums.com/showpost.php?p=46231808&postcount=9

Whether or not the strikes are detected at the same time depends entirely upon where the person doing the detection is. The difference is that the person who is moving on the train infers that, when he extrapolates back to the time the light from the strikes started at the poles, knowing the speeds of the poles and the speed of light, he finds that the flashes were not simultaneous.

 

[Frumious Bandersnatch]

Exactly... what... I said? Frequency is based upon wavelength and the speed of each wave. Frequency can be changed by either changing the wavelength or the speed of the wave.

This is exactly what you said

Posted by The Gregorian
*He'll measure a different frequency, not wave length.

Wave length is a function of any given wave regardless of observer. People moving relative to a wave will see the same wave length at a different frequency.

I said it does not make sense because it does not make sense. The only way you can see the same wavelength at a different frequency is for the speed of the wave to change, such as when light enters a medium of different refractive index. Movement relative to the orgin of the wave does not change its speed. The speed of light in a vacuum is always exactly C. Lamda = c/f. In any medium of constant refractive index, such as a vacuum where n = 1.0000, c never changes so f can't change without Lamba changing.

To say that light's frequency is observed to change via the doppler effect, but it's relative speed is ALWAYS the same indicates that the redshift/blueshift is a change in light's wavelength... But why would the form of the wave change depending upon the actions of an observer simply by observing it?

Both the frequency and the wavelength are changed by the Doppler shift.

Namely... we can tell based on how frequencies of light is shifted, the speed toward or away from us the light's source is traveling.... If the speed of light is fixed, that means the wavelength varies depending on our speed relative to the light's source?

Yes. This is well known.

Meaning we can change the wavelength of light by moving relative to it...

Yes.

Or... that we change the perceived frequency of light (like any other wave) not by changing the waveLENGTH, but by changing our speed relative to the wave, thereby changing the wave's relative speed.

The wavelength and frequency we observe change with relative motion.

Where do you see the problem? Other than "oh noz! that's not in my textbook."

The problem is that what you said that I quoted above is just plain wrong. We have been over this ground at least once before.

Reality is indifferent to you inability to comprehend special realtivity.

 

[Joe_Sixpack]

Greater forces acting upon the particle. Of course wind resistance and whatnot isn't a factor here, but E=MC^2 admits that all matter is simply energy in another form... Unlikely static since everything tends to spin (from galaxies to atoms). Decay is basically part of a given chunk of material falling off... Think of a helicopter blade for a second. At a given engine RPM, the blade travels at the same speed regardless of the helicopter itself is stationary or moving relative to the earth... As the helicopter moves, forces act upon the rotor blades much differently because the advancing blade may be moving far faster than the retreating blade. Of course this example is flawed because the difference in forces for a helicopter is generally wind resistance, which doesn't exactly play a role in sub-atomic particals, but it is possible that there COULD be some force that is exerted differently when the particles stationary rotation is augmented by linear movement. Exactly what that is? I dunno... But it's more likely that there is some -force- acting upon the particle than time itself bending.

No it isn't because one your helicopter analogy is useless because that is an accelerating reference frame. Linear motion is ALWAYS relative to something else. Therefore this mystery force would have to work on the cesium atoms differently depending upon the reference frame of the observer - on the plane there is no mystery force, from the ground there is another, and from the passing spaceship observing the plane there is another. This would mean that the laws of physics would not be constant in all reference frames which even you agreed with earlier.

Go back to the simplest clock - emitter firing a photon some set distance. You can set all your clocks by it - the photon always takes d/c time to hit the emitter. Now align that clock in the direction of travel and move at some hugely high speed past a planet. You still observe your clock working exactly as it should taking d/c time to complete the distance. Someone on the planet however sees something different because the photon is moving a c the moment it leaves the emitter but to him the sensor is moving away from it at some speed approaching c so the distance traveled increases and the time it takes the emitter to hit that sensor is longer. Two people observing the same clock and the clock is working at different speeds to each of them. This is not an illusion because of symmetry, that clock is your basic reference for all time changes - therefore all clocks on the ship, mechanical, atomic, etc., will all be slower according to the observer from the ground as the photon emitter. Now is this a trick of perception? Maybe you could describe as such but this illusion feels very real to the different participants (i.e. to them time is just progressing normally) but they meet in the same reference frame they will notice that they aged differently.

Again - I ask myself why I bother.