The Fundamental Postulate Of Special Relativity Is Self-Contradictory

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The discussion centers on the claim that the fundamental postulate of special relativity, which states that the speed of light is constant at 299,792,458 meters per second in all inertial reference frames, is self-contradictory. The argument presented involves two photons moving in the same direction, suggesting that if one defines a new inertial reference frame based on one photon, the other photon would appear to have a speed of zero, contradicting the postulate. Participants debate the validity of this reasoning, emphasizing that photons cannot serve as inertial reference frames since they always travel at the speed of light and cannot be at rest relative to each other. The conversation also touches on the limits of special relativity and the nature of reference frames. Ultimately, the claim of contradiction remains contested, with some asserting that the postulate is not inherently flawed.
  • #31
I really hope StarThrower hasn't spend all ten years studying Special Relativity. :smile:
 
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  • #32
Certainly, light always travel in c. Here SR right.
But Einstein had not made a suitable explanation, why it so.
Naturally, absence of a convincing explanation results in doubts in validity of this postulate. The constant mess with frames of reference does not promote the understanding of this the postulate also. In my opinion, there is the best way for an explanation of the light’s speed independence from the speed of radiator.
It is necessary to take into account, that the photon can be found out only face to face. It can’t be observed, and therefore can’t be measured from the “sideways”.
ST (StarThrower),
You are right too (though it can sound strange).
The photons radiated by a short laser pulse will achieved the target
SIMULTANEOUSLY. This an experience shows, that they have passed this way with an identical
speed.
The concept "relativity" is applicable to any material objects, except of light.
They exist in RELATIVE TIME.
Speed of Light is ABSOLUTE.
Light exist in ABSOLUTE TIME.
 
  • #33
Michael,
You fail to understand the meaning of postulate. Einstein is not obligated to prove anything about his postulate. That is the nature of a postulate. You most certainly cannot learn anything other then the results of a constant c by studying Relativity. It is after all a development that explores the implications of a constant speed of light.

If you wish to find the roots of the constancy of c you need to study and understand the work of Clerk Maxwell. The origins of a velocity that is independent of the source, is Maxwell's equations cast in the form of the wave equation. When this result was published in the late 1860s the world of Physics was changed forever. How to rectify the source independence of the speed of Electromagnetism with the accepted and well understood precepts of Classical Mechanics was the single largest issue in Physics of that era. Due to that Einstein was able to postulate a constant c. Physicist of that era did not blink an eye at the postulate because they had spend a generation attempting to disprove the constancy of c. They failed.
 
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  • #34
Ok Eyesaw, you win, let's attempt to make some sense of this post.


Eyesaw said:
This is just another example of the violation of simple logic by the SR postulates.

What is an example of the SR postulates. Or are you saying the SR postulates are an example of a violation of logic.

Do you even know what the postulates of SR are?

Inside an arbitrary set of "rest coordinates", if J is moving at c with respect to M and M is moving at v with respect to L then J- whether it represent jumping frogs, waffling ducks, bald eagles, flying beagles, or photons- must be moving at c +/-v with respect to L, else it would lead to reductio absurdum- i.e. you start
out with the assumption that there is velocity between M and L but because
of the logic of SR, you end up with the conclusion that there is no velocity between
M and L.
That is one heck of a sentence, but what does it say? This looks to be some kind stawman construction that really means nothing.

What I say is that you cannot measure time or space from the frame of reference of a photon, therefore you cannot measure the speed of a photon.
A photon, after emitted in vacuum, is not in anyone's inertial frame unless we pondered an ether- thus,

it is painfully obvious that different observers moving
through the empty vacuum at different velocities must have a different velocity
with respect to the photon because 2+2 = 4, 3+3 = 6, 4+4 = 8, 5+5 =10 and 6+6
= 12.

[ Sure, one can still obtain the speed of the photon through space as a constant
after subtracting the velocity of the observer through space but this was not the
method chosen by Einstein in SR, even though it is the most simple way to achieve
constancy of c that is independent of source. In lieu of using simple math and
common sense, the physics community have decided warping space and time is cooler so never mind that it is wrong.

Wow, an even better sentence. Are you saying that the speed of light is not constant to all observers?

Does the piece in bold really say what I think it does? Welcome to the world of Aristotle, your logic is impeccable your science is non existent.

In view of learning anything about the modern state of physics you choose to talk nonsense.
 
  • #35
Hurkyl, perhaps you meant 'derive a contradiction' for 'derive a fallacious conclusion'?

I didn't want to say contradiction because, in principle, a counter-argument could simply derive a disagreement with reality instead of a contradiction within SR. Fallacious was probably the wrong word because it's generally inferred to be speaking about the logic and not the result, but I suppose most adjectives used there are the same.
 
  • #36
Integral said:
Do the math and weep. Photons do not know time or distance. Therefore do not know velocity. That is proper applcation of SR. If you do not use the tools correctly you do not get meaningful results. SR does not specify a number for c it only says that it is constant. In the frame of reference of a photon the velocity of all photons is zero. That is a constant and satisfies the postulate of SR.

Edit:
Added a lost negation.

No sir. Photons, like other things, move relative to each other. It certainly is meaningful to view motion from the reference frame of a photon, regardless of whether or not the reference frame is inertial. So, regardless of whether or not a coordinate system whose origin is a photon is inertial, certainly other photons move in this frame relative to the origin with different velocities.

Kind regards,

The Star
 
  • #37
Star.
What is the basis of your words? Are these your personal thoughts? What experimental evidence do you base your ideas on? Please provide some references to your sources.
 
  • #38
Integral said:
Star,
Let me but this way, your assertion that you can measure the velocity of a photon from the frame of reference of a photon is incorrect. In SR there are no meaningful measurements that can be made in the frame of reference of a photon. So your example is erronous, a photon cannot see the speed of a second photon.

But then since you have convinced yourself that SR is invalid without the ability to correctly apply it or even understand it. I do not expect you to accept it.

But then since it is incorrect in would not any application of it lead to incorrect results. You applied it therefore your results are incorrect.

The issue in this thread isn't about measuring photon speed in the frame of reference of a photon. It is about whether or not the fundamental postulate of the special theory of relativity self-contradicts. At any rate, when a photon moves in any reference frame, it moves through that frame with some velocity, regardless of whether or not that velocity can be measured. And so we can use binary logic to at least check the consistency of the theory, because we are supposed to know the meaning of the term 'velocity'.

Kind regards,

The Star
 
  • #39
Then why are you attempting use the incorrect example of a photons frame of reference. It is YOU who have proposed that argument. I have only shown you why your argument is incorrect. You are not applying binary logic you are attempting to tell us how one photon perceives another. I have provided you with what SR has to say about that situation. That is a photon cannot perceive motion, therefore does not see other photons moving at c. Your basic hypothesis is incorrect. Therefore your conclusions are invalid.

Are you
 
  • #40
Integral said:
Then why are you attempting use the incorrect example of a photons frame of reference. It is YOU who have proposed that argument. I have only shown you why your argument is incorrect. You are not applying binary logic you are attempting to tell us how one photon perceives another. I have provided you with what SR has to say about that situation. That is a photon cannot perceive motion, therefore does not see other photons moving at c. Your basic hypothesis is incorrect. Therefore your conclusions are invalid.

Are you


You are getting off track. The question is this:

Is a reference frame whose origin is a photon an inertial reference frame?

Kind regards,

The Star
 
  • #41
Integral said:
Ok Eyesaw, you win, let's attempt to make some sense of this post.




What is an example of the SR postulates. Or are you saying the SR postulates are an example of a violation of logic.

Do you even know what the postulates of SR are?


That is one heck of a sentence, but what does it say? This looks to be some kind stawman construction that really means nothing.

What I say is that you cannot measure time or space from the frame of reference of a photon, therefore you cannot measure the speed of a photon.


Wow, an even better sentence. Are you saying that the speed of light is not constant to all observers?

Does the piece in bold really say what I think it does? Welcome to the world of Aristotle, your logic is impeccable your science is non existent.

In view of learning anything about the modern state of physics you choose to talk nonsense.


You are the one repeating the nonsense that a "moving observer" will make the same observations of any event, be it photon speed or whatever, observed by the "stationary observer". What a load of crap- there is no difference between a moving observer and a stationary one then, therefore everything is standing still just like Zeno said. You are really stupid, I mean really stupid to think the time dilation and length contraction effects are real changes in physical space and time and not just artificacts of the transformation method. The theory you support is nothing short of mysticism.
 
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  • #42
StarThrower said:
You are getting off track. The question is this:
Is a reference frame whose origin is a photon an inertial reference frame?
According to the University of Dallas, the second postulate of SR (I'm not calling it the fundamental postulate, that sounds very flowery as there are two equally-important postulates) is:

Light is always propagated in empty space with a definite velocity c, which is independent of the state of motion of the emitting body.

A second source on this postulate is Wikipedia's definition, which states:

The speed of light in vacuum is the same to all inertial observers. This postulate has been verified experimentally.

As far as you're concerned, StarThrower, the part about EXPERIMENTAL VERIFICATION will be totally useless, so you'll ignore that. In any case we have to define what an inertial observer is. I found this rather expansive definition provided by a retired nuclear engineer here:
To be inertial, the observer, or coordinate system must satisfy the
following properties:

1) The distance between any two points in the coordinate system must be
time independent, the distance is not different for different times,

2) The clocks, assumed distributed throughout the coordinate system, are
synchronized (the time reported is not dependent on the location of the
clock) and run at the same rate throughout the coordinate system (the
observer), and

3) The geometry of space at any constant t is Euclidean. The simplest
way to think of a Euclidean space is that it is a space (a coordinate
system) in which the geometry most people are familiar with is
applicable. If you were a mathematician, you would probably take issue
with that last sentence, claiming it to be an oversimplification, but it
should work in this instance.
There are further stipulations placed on inertial frames of reference, namely they must take up VERY small volumes of space (because otherwise parallel lines tend to converge due to the gravitational affect of nearby massive bodies and the curvature of space...this is addressed by #3 above stipulating that space must be "flat" in the inertial frame), and they must be nonrotating with respect to distant cosmic mass.

I can accept that we could concentrate on a very small distance traveled by a photon, so #3 COULD apply to a photon, but how are #1 and #2 applied to a photon? Photons don't even experience time, so there is no distance between any two points as far as a photon is concerned. Therefore it could not define a frame of reference (which is a system of coordinates) because the length of the ct, x, y, z axes would be zero. As far as a clock, would it ever tick once (assuming it's massless and traveling at c)? Could there ever be more than one clock in the reference frame, because there are no points in the reference frame OTHER than the origin?
 
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  • #43
StarThrower said:
Since they are moving in the same direction, the difference in their velocity vectors (as defined in F1) is equal to zero. Thus, the two photons are not moving relative to each other.
This is from your first post, StarThrower. I challenge you to tell me the difference in their velocity vectors if photons A and B are traveling in

a) perpendicular directions
b) directions separated by angle \theta where \theta = 45^\circ
c) opposite directions

EDIT:
Show your work, please.
 
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  • #44
And let's further expand upon this. Suppose photonic rest frames are valid.

Allow me to specify the worldlines of two photons in the reference frame of an ordinary observer:

In the coordinate system (t, x) of the ordinary observer:

Photon 1's worldline is given by the equation x = ct.
Photon 2's worldline is given by the equation x = ct.

Now, transform into the coordinates (t', x') of photon 1's rest frame. What are the worldlines of photon 1 and photon 2?

(again, please show your work)
 
  • #45
Severian596 said:
According to the University of Dallas, the second postulate of SR (I'm not calling it the fundamental postulate, that sounds very flowery as there are two equally-important postulates) is:

Light is always propagated in empty space with a definite velocity c, which is independent of the state of motion of the emitting body.

A second source on this postulate is Wikipedia's definition, which states:

The speed of light in vacuum is the same to all inertial observers. This postulate has been verified experimentally.

As far as you're concerned, StarThrower, the part about EXPERIMENTAL VERIFICATION will be totally useless, so you'll ignore that. In any case we have to define what an inertial observer is. I found this rather expansive definition provided by a retired nuclear engineer here:

There are further stipulations placed on inertial frames of reference, namely they must take up VERY small volumes of space (because otherwise parallel lines tend to converge due to the gravitational affect of nearby massive bodies and the curvature of space...this is addressed by #3 above stipulating that space must be "flat" in the inertial frame), and they must be nonrotating with respect to distant cosmic mass.

I can accept that we could concentrate on a very small distance traveled by a photon, so #3 COULD apply to a photon, but how are #1 and #2 applied to a photon? Photons don't even experience time, so there is no distance between any two points as far as a photon is concerned. Therefore it could not define a frame of reference (which is a system of coordinates) because the length of the ct, x, y, z axes would be zero. As far as a clock, would it ever tick once (assuming it's massless and traveling at c)? Could there ever be more than one clock in the reference frame, because there are no points in the reference frame OTHER than the origin?

The source which you cited is not reputable. The definition given is not the internationally accepted definition. I did a search on google (inertial reference frame definition) here you go:

Web Definition

Definition 1: a coordinate system in which Newton's first law of motion is valid

Source 2

Definition 2: inertial frame, inertial reference frame - a coordinate system in which Newton's first law of motion is valid

http://appletree.mta.ca/courses/physics/4701_97/EText/Inertial.html

Definition 3: An inertial reference frame is one in uniform motion (all accelerometers read zero). In special relativity we think of inertial reference frames as those which are moving at a constant velocity. An observer, without being able to make reference to the rest of the universe (e.g. in a windowless room) cannot determine his or her velocity. Within special relativity we think of inertial referenceframes as reference frames in constant velocity motion.

http://id.mind.net/~zona/mstm/physics/mechanics/framesOfReference/inertialFrame.html

Definition 4: An inertial frame of reference has a constant velocity. That is, it is moving at a constant speed in a straight line, or it is standing still. Understand that when something is standing still, it has a constant velocity. Its velocity is constantly zero meters per second.

The following source (Stanford university) is reputable:

Source 5
Definition 5:

Space and Time: Inertial Frames
A “frame of reference” is a standard relative to which motion and rest may be measured; any set of points or objects that are at rest relative to one another enables us, in principle, to describe the relative motions of bodies. A frame of reference is therefore a purely kinematical device, for the geometrical description of motion without regard to the masses or forces involved. A dynamical account of motion leads to the idea of an “inertial frame,” or a reference frame relative to which motions have distinguished dynamical properties. For that reason an inertial frame has to be understood as a spatial reference frame together with some means of measuring time, so that uniform motions can be distinguished from accelerated motions. The laws of Newtonian dynamics provide a simple definition: an inertial frame is a reference-frame with a time-scale, relative to which the motion of a body not subject to forces is always rectilinear and uniform, accelerations are always proportional to and in the direction of applied forces, and applied forces are always met with equal and opposite reactions. It follows that, in an inertial frame, the center of mass of a system of bodies is always at rest or in uniform motion. It also follows that any other frame of reference moving uniformly relative to an inertial frame is also an inertial frame. For example, in Newtonian celestial mechanics, taking the “fixed stars” as a frame of reference, we can determine an (approximately) inertial frame whose center is the center of mass of the solar system; relative to this frame, every acceleration of every planet can be accounted for (approximately) as a gravitational interaction with some other planet in accord with Newton's laws of motion.

This appears to be a simple and straightforward concept. By inquiring more narrowly into its origins and meaning, however, we begin to understand why it has been an ongoing subject of philosophical concern. It originated in a profound philosophical consideration of the principles of relativity and invariance in the context of Newtonian mechanics. Further reflections on it, in different theoretical contexts, had extraordinary consequences for 20th-century theories of space and time.

End of source quotes

As you can see, some sources say that an inertial reference frame is a reference frame in which Newton's first law is true, other more reputable sources say that an inertial reference frame is a reference frame in which all three of Newton's laws are true.

What matters here, is the definition which Einstein used in his formulation of the fundamental postulate of the special theory of relativity, which is this:

An inertial reference frame is a reference frame in which a body which is not subjected to an outside force will either

A. Remain at rest (if at rest).
B. Continue to move in a straight line (if already moving in a straight line).

And a body which is subjected to an outside force F, will obey the following equation:

F = dP/dt = d(mV)/dt

Where m is the object's mass, and V is the objects velocity vector.

And there will be an action/reaction pair for this object. The other object will experience the same force F, but in the opposite direction.


Regards,

The Star
 
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  • #46
The source which you cited is not reputable. The definition given is not the internationally accepted definition.

You'll notice, however, that the three facts listed are true in both Newtonian and SR inertial reference frames. You'll recognize that they (partially) specify a spatial reference frame together with some means of measuring time.
 
  • #47
And a body which is subjected to an outside force F, will obey the following equation:

F = dP/dt = d(mV)/dt

Assuming, of course, P = mV.
 
  • #48
Maxwell's equations for electromagnetism assumed the very same inertial frames that Newtonian mechanics assumed. Don't let all the different definitions of inertial frames fool you. (Though, to be sure, one definition may be better than another.) Yet, Maxwell's equations predicted just one value, c, for the speed of light. Logically, StarThrower has to assert that Maxwell's equations are invalid, contrary to 200 years of experiment.
 
  • #49
Hurkyl said:
Assuming, of course, P = mV.

That is the equation to focus on Hurkyl. When Einstein originally formulated the fundamental postulate of the special theory of relativity, he had not yet developed the concept of mass which depends upon speed.

This early oversight on Einstein's part does not alter the definition of inertial reference frame which he used, and this brings me back to the original question.

Is a reference frame whose origin is a photon an inertial reference frame?

Kind regards,

The Star
 
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  • #50
outandbeyond2004 said:
Maxwell's equations for electromagnetism assumed the very same inertial frames that Newtonian mechanics assumed. Don't let all the different definitions of inertial frames fool you. (Though, to be sure, one definition may be better than another.) Yet, Maxwell's equations predicted just one value, c, for the speed of light. Logically, StarThrower has to assert that Maxwell's equations are invalid, contrary to 200 years of experiment.

I would argue as follows:

Maxwell's equations predict one universal value for the speed of light relative to the source. They do not say that the speed of light is independent of the motion of the source.

Kind regards,

The Star
 
  • #51
Are you planning on answering mine and Hurkyl's questions, StarThrower?
 
  • #52
Maxwell's equations predict one universal value for the speed of light relative to the source.

In order to argue this, you really should point out something source related in the wave equation.
 
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  • #53
I found this through google.com searching:

http://www.google.com/search?q=cache:QDMd3MVoHcoJ:www.physicsforums.com/archive/topic/11184-1.html+photon%27s+reference+frame&hl=en&ie=UTF-8

This topic (and the one we're in) is fun for me because it only reinforces my understanding of SR. Unfortunately for StarThrower the discussion isn't novel and apparently he isn't the genius (or alien from 83 million light years away) that he thinks he is.

But anyway I'm still wondering if he's going to oblige us with some answers to our questions...and I won't tell you my theory on whether StarThrower = Tempest.
 
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  • #54
StarThrower said:
Theorem Of Special Relativity: If all coordinates of reference frame F2 are moving in a straight line at a constant speed in some inertial reference frame F1, then F2 is also an inertial reference frame.
Ah-hA! Very interesting that StarThrower started off this entire thread with this "theorem of SR." You know why it's interesting? I was reading through the post I mentioned in my last message and came across StarThrower's contribution to the conversation. He admitted that, "This post has really got me thinking," and then he summarized his ideas with the following paragraph:
StarThrower said:
That being said, if you can now show that [the photon's rest frame] MUST be an inertial reference frame, you would likely be onto something. And so this is why you have gotten me thinking. Here is what would have to be done. You would have to prove that if X is an inertial reference frame, and Y is a reference frame whose origin is moving at a constant speed relative to the origin of X, and whose axes aren't rotating in frame X, then Y is an inertial reference frame.

Then, because the photon is moving at a constant speed in the atomic frame, it would follow by a theorem not yet proven, that a frame in which the photon is at rest, is an inertial reference frame. And since one of the consequences of the special theory is that in any inertial reference frame the speed of any photon is c, you would have accomplished something.
Have you proved this then, StarThrower? You made a powerful statement in your opening message by saying that it's a "theorem of SR." Whose theorem is it? Can you explain it? I'm still reading the other thread (click on my link in my last post) to see what's said, but I thought the content very appropriate to post here...
 
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  • #55
You found a contradiction after assuming that the photon's rest frame is an inertial frame of reference. Congragtulations! Very well, then: Let's agree that every photon's rest frame is NOT an inertial reference frame. Let's please not push SR out of the boundaries of its validity. It was never meant to be a theory for ALL situations. There is after all a reason why Einstein went on to develop GR. And, have you never heard of efforts to develop GUTs? Have you got no gut feeling for such things whatsoever (sorry couldn't resist).
 
  • #56
I just want to make sure...you're addressing more than one person in your post, right? You use 'you' a few times...

:wink:
 
  • #57
Jesus Christ, this thread is confusing the hell out of me. Can I safely assume what Integral is saying is right?
 
  • #58
What did he say, JJ? I mean, which thing that he said are you referring to?
 
  • #59
StarThrower said:
You are getting off track. The question is this:

Is a reference frame whose origin is a photon an inertial reference frame?

Kind regards,

The Star
I'm not sure anyone answered this succinctly. The answer is NO.

Therefore, your example is invalid for an examination of SR. It quite simply doesn't apply.
Jesus Christ, this thread is confusing the hell out of me. Can I safely assume what Integral is saying is right?
Yes, JJ.

As for trying to follow this discussion, its probably best to let it go: in your first post, you demonstrated an understanding of SR that far exceeds StarThrower's. But trying to make sense of this confusing mess is like trying to untangle spaghetti and not worth your effort.

Keep asking the good questions and welcome to the forum.
 
  • #60
Severian:

That concepts of distance, time, and motion are unapplicable from the point of view of a photon. I figure that because of that, the idea of the speed of light is only true with reference frames moving below it. The speed of light is a good reference, but not a good observer.
 

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