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The Theory of Relativity

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In my philosophy class today, an interesting discussion occured when one of my classmates brought up the issue of Einstein's Theory of Relativity. He quoted a postulate developed by leading physicists which stated something to the effect of "If a beam of light was fired at a train while it was moving and the doors of the train opened via light sensory mechanics. To an observer inside the train, the doors would open simultaneously but, to an observer standing outside, they would be off-timed, and yet, this is not a contradiction. My teacher explained this as a proof of space being a relative concept of location between objects. How does this differ from primacy of conciousness or any other idea of subjectivism?

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In my philosophy class today, an interesting discussion occured when one of my classmates brought up the issue of Einstein's Theory of Relativity. He quoted a postulate developed by leading physicists which stated something to the effect of "If a beam of light was fired at a train while it was moving and the doors of the train opened via light sensory mechanics. To an observer inside the train, the doors would open simultaneously but, to an observer standing outside, they would be off-timed, and yet, this is not a contradiction. My teacher explained this as a proof of space being a relative concept of location between objects. How does this differ from primacy of conciousness or any other idea of subjectivism?

I am no expert - far from it - but I think that Eienstein's point was that it appears different, not that it is different.

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My teacher explained this as a proof of space being a relative concept of location between objects.
No thought-experiment is a proof, and no postulate is a proof; and the claim is certainly not an axiom. It may well be true, nevertheless. What we learn from this, if we assume that Einstein's theory is right, is that "space" is a relation between objects (and not a "relative concept").
How does this differ from primacy of conciousness or any other idea of subjectivism?
The relationship between two frames of reference can be known and measured as being objectively the same, regardless of any consciousnesses doing the measuring. It does not depend on the individual mind, it depends on the specific physical context.
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What I'm trying to ask is, space is a relative concept so far as it is a concept of the relation between objects but objectively definable as such. However, despite the perception of the two perceivers described in the incident, motion either begins separately or simultaneously, there is no middle ground, in which case, how can this postulate be true? Is it? My philosophy teacher is an Objectivist and was actually the person who introduced me to Ayn Rand, and yet, he agrees with this postulate. How could an idea like this fit into Objectivism? Does it?

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I guess you will need to explain in more detail exactly what this postulate is. These physics stories often lose a lot in translation. I assume that the train is moving at relativistic speeds; so the notion "at the same time" is what doesn't make sense. Well, it does intuitively, but the point is that time is not a universal coordinate system tuned to god's pocket watch. The flow of time on that light-speed train is not the same as on the ground.

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The train is moving with two perceivers, one inside it and one outside. The doors are on the sides of the train. A light sensor on both doors triggers them to open as they hit by the same light source that is set equidistant from the two of them. The sensors receive the light and both doors open. To one of the observers, they open simultaneously and to the other, they open at different times. I'm not arguing the perception, I'm arguing, either they really open at the same time or not. Does the postulate that it's actually a different truth for each perceiver hold any truth?

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How does this differ from primacy of consciousness or any other idea of subjectivism?

It is difficult to grasp Relativity unless one starts at the beginning, but basically it is based on the postulate that light travels at the speed of light regardless of how fast the source is moving. If one makes a clock out of a beam of light bouncing back and forth between two mirrors, one would get this [ignore the little dots, I had to put those in to secure the proper spacing of the light beam]:

-------

...|

...|

...|

-------

But, if the observer was moving relative to the clock, one would get this:

--------

...|

../ \

/ ....\

---------

In other words, the person holding the clock would see it as a beam of light going up and down, whereas someone moving relative to the clock would see it as following an angled path. In both cases, the beam of light must be seen as traveling back and forth between the mirrors, but to the man holding the clock, it takes one second for the beam to go back and forth, but to the man moving, it takes longer than a second because the distance the light travels is greater. Because of this, and assuming light travels at the same speed in both cases, one has to use complicated mathematics to transcribe one frame of reference to another. The equations work, I mean they are predictive to real observations, but some of the terminology is misleading, such as saying that space and time are bent or curved due to relative motion.

Put another way, two events that occur at the same time in one frame of reference do not necessarily occur at the same time in another frame of reference; it all goes back to the clocks running differently due to relative motion.

It is not subjectivism, because it is something that can actually be measured in reality, it's not just imaginary, or not just of the mind (which would make it subjective). It is an observed fact of reality, at least insofar as the equations make accurate predictions of differences in calculated results coming about due to relative motion.

By the way, what does your ID mean in English?

Edited by Thomas M. Miovas Jr.
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This all stems from an experiment in the late 1800's that promised to measure the velocity of Earth through space.

Imagine a light source with a light detector, and a mirror. The light source pulses light to the mirror and the detector is able to measure the round trip time of the pulse.

If you're standing still in space, the experiment looks like Thomas' first diagram, pulse goes out, hits the mirror and comes straight back. The distance traveled is 2d, where d is the distance between the source and the mirror.

If you're moving through space and shooting perpendicular to your direction of velocity, the path looks like Thomas' second diagram, a 'V' shape, which is slightly longer than 2d.

If you're moving and shooting in the direction of travel, then the pulse needs to catch up to the mirror, then shoot back and meet the detector head on. In this case the distance is longer than 2d, but (I believe) shorter than the 'V' shaped path.

The two distances described by the moving mirror are different, so if you run the experiment and rotate the equipment, you should very quickly detect the difference in distance and discover in what direction you're traveling through space.

That was the idea, anyway. What they found is that the distances were the same, regardless of which direction you pointed the equipment. This result could only mean one thing: Earth was standing still in space. But that was an apparent contradiction (they tried it at different times of the day, and year, just in case). It was a big problem until Einstein came along.

He deduced that since the distances appeared the same, something must be going on with dimensions. Using a little geometry and algebra, he came up with an equation of length contraction that mathematically explained the identical distance measurements. Space must be compressed in the direction of velocity, he concluded. Then he went a little further, hypothesizing that your frame of reference (i.e., velocity) can never be deduced by internal measurements, he set out to explain how the distance at rest could seem the same as the distance in motion, since we know the distance traveled by the pulse is greater in motion, there must be something going on with time, he surmised. Time must be dilated at velocity, he concluded, and showed the equations that explained it. He had a couple more theories, one of which showed why you can't accelerate through the speed of light.

Now here's the train problem: Imagine a train car traveling left to right across the monitor (seen from top):

____________v___________

|_______________________|

|_______________________|

|______o_________o______|

where the 'v' is a light source and the 'o's are light sensors. To someone on the train the light flashes and both sensors receive the pulse at the same time.

Now, imagine you're outside the train and the light flashes. In your frame of reference the sensor on the left is moving closer to the light source and the sensor on the right is moving away from the light source. Clearly, in your frame of reference, the sensor on the left is going to trigger before the sensor on the right does.

Now the question is, "who's right?" Einstein says that because there's no way to figure out which frame is actually moving and which is standing still, that they're both right. In the "moving" frame they both flash simultaneously, in the "stationary" frame of reference, they stagger.

Ironically, Einstein didn't win the Nobel for this work, but for the shared explanation of the photoelectric effect, which ushered in the era of quantum mechanics, which he never fully accepted.

Edited by agrippa1
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It was a big problem until Einstein came along.

He deduced that since the distances appeared the same, something must be going on with dimensions. Using a little geometry and algebra, he came up with an equation of length contraction that mathematically explained the identical distance measurements. Space must be compressed in the direction of velocity, he concluded. Then he went a little further, hypothesizing that your frame of reference (i.e., velocity) can never be deduced by internal measurements, he set out to explain how the distance at rest could seem the same as the distance in motion, since we know the distance traveled by the pulse is greater in motion, there must be something going on with time, he surmised. Time must be dilated at velocity, he concluded, and showed the equations that explained it.

Actually, the equations were developed by Lorenz, and formed a part of the Lorentz Ether Theory. This is why the transformation is called the Lorentz transformation. The Special Theory of Relativity is really a mixture of the Lorentz Ether Theory and bad philosophy.

Edited by Capitalism Forever
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By the way, what does your ID mean in English?

Stuzal Iuday means "the proud, stubborn mule" whilst creala means "creative" and Atla, even though it sounds more like Atlas, is actually a concept closer to that of Aristotle's Prime Mover.

That has never made sense to me. Could you or someone else please explain how than can be? It seems to me to be nonsensical.

Time is not an independent absolute, it is an objective measure of relative motion. The ground moves slower so "time" is also moving slower within it.

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Actually, the equations were developed by Lorenz, and formed a part of the Lorentz Ether Theory. This is why the transformation is called the Lorentz transformation. The Special Theory of Relativity is really a mixture of the Lorentz Ether Theory and bad philosophy.

Einstein derived the Lorentz equations directly from his thought experiment using two premises (relativity and invariant light speed) and simple algebra. He did not start out trying to apply Lorentz transforms to space-time, but rather worked backwards from his solutions to conclude that Lorentz transformations formed the basis of special relativity.

I'm not sure what you mean by "bad" philosophy. Einstein started with a contradiction (the results of Michelson-Morley), questioned his premises (invariant space and time), and derived a solution that eliminated the contradiction. Since his conclusions have been borne out by modern experiments, I would say that his philosophy led him intellectually to an understanding of reality beyond his sensory abilities. That would seem to be the goal of "good" philosophy.

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A lot of it has to do with the fact that light travels independent of the source once it is emitted -- in other words, once emitted, it travels as it does and the source is no longer a factor at all. It is easier to see the effects (with proper graphics) if one assumes light travels in waves emanating our from the source, in which case one moving relative to the source means that one detects a different part of the wave. In the train example, if a spherical pulse was emitted from the light source, it would radiate out spherically from the source, and the detector moving towards the wave would detect it before the detector moving away from the wave.

And the thing is, as far as we know by the theory, there is no absolute frame of reference -- i.e. no known grid in which one can say that one is stationary relative to "space itself". So, you don't really know who is moving and who is stationary, except for some reference frame.

Here's another aspect of relativity: one gets a current if a magnet is moved near a wire, but it doesn't matter if the wire is stationary and the magnet is moving, or if the wire is moving and the magnet is stationary. All one needs is relative motion between the wire and the magnet -- how either is moving relative to, say, a desk top is irrelevant.

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Einstein derived the Lorentz equations

No, Lorentz derived the Lorentz equations. That's why they are called the Lorentz equations. :thumbsup:

I'm not sure what you mean by "bad" philosophy.

From http://en.wikipedia.org/wiki/Lorentz_ether_theory:

Einstein explained that he borrowed the principle of the constancy of light from Lorentz's immobile ether, but he recognized that this principle together with the principle of relativity makes the ether useless and leads to special relativity. It is also known[66] that he read Poincaré's 1902-book „Science and hypothesis“ before 1905, which included:

philosophical assessments on the relativity of space, time, and simultaneity

the opinion that a violation of the relativity principle can never be detected

the possible non-existence of the ether

many remarks on the non-Euclidean geometry.

And just what was the philosophy of this gentleman Poincaré that shaped the thought of Einstein?

Poincaré wrote in the sense of his conventionalist philosophy in 1889: [29]“ Whether the ether exists or not matters little - let us leave that to the metaphysicians; what is essential for us is, that everything happens as if it existed, and that this hypothesis is found to be suitable for the explanation of phenomena. After all, have we any other reason for believing in the existence of material objects? That, too, is only a convenient hypothesis; only, it will never cease to be so, while some day, no doubt, the ether will be thrown aside as useless. ”

He also denied the existence of absolute space and time by saying in 1901:[30]“ 1. There is no absolute space, and we only conceive of relative motion ; and yet in most cases mechanical facts are enunciated as if there is an absolute space to which they can be referred. 2. There is no absolute time. When we say that two periods are equal, the statement has no meaning, and can only acquire a meaning by a convention. 3. Not only have we no direct intuition of the equality of two periods, but we have not even direct intuition of the simultaneity of two events occurring in two different places. I have explained this in an article entitled "Mesure du Temps" [1898]. 4. Finally, is not our Euclidean geometry in itself only a kind of convention of language?

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Relativity is a theory like any other theory in physics - it simply predicts with some level of accuracy observed phenomena within the universe. It happens to do so by taking into account the reference frame of the observer. Physics is and was never meant to give some ultimate absolute truth about the universe.

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Now that's what I call bad philosophy!

Yes, there is a lot of bad philosophy in physics, especially the notion that physics is about equations rather than about what exists in reality. The Ancient Greeks, primarily Aristotle coined the term we get the word "physics" from -- roughly phousies -- which meant a rational study of nature; and later it became distilled down to mean something like the study of motion with Newton's laws of motion that were mathematical. It's a big topic, and there are people working on coming up with a better philosophy of science. In the mean time, there are a lot of unanswered questions that modern physicist would rather not discuss, such as is there an aether or not; they basically believe that since we have equations that work, we don't have to worry about that. But I am curious about those kinds of questions and wrote a poem about the aether that I put on my website.

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No... Lorentz derived them first. That's why! :thumbsup:

Well, once they were derived, you didn't have to derive them again, did you? What Einstein gave was (in part, at least) an interpretation of the Lorentz equations, and--to answer your question--

I'm not sure what your objection is here. Are you disputing the verity of Special Relativity based on your interpretation of its philosophical roots? :o

--it is that interpretation that I am calling a fruit of bad philosophy.

A multi-million dollar prize awaits you in Oslo...

I'd rather not get any prize Al Gore has received! :)

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Well, once they were derived, you didn't have to derive them again, did you? What Einstein gave was (in part, at least) an interpretation of the Lorentz equations, and--to answer your question--

--it is that interpretation that I am calling a fruit of bad philosophy.

I'd rather not get any prize Al Gore has received! :P

Okay, you're right... Nothing is relative, everything is absolute... Einstein was wrong, you are right... Thanks for setting me, and the rest of the world, straight...

:lol:

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In my philosophy class today, an interesting discussion occured when one of my classmates brought up the issue of Einstein's Theory of Relativity. He quoted a postulate developed by leading physicists which stated something to the effect of "If a beam of light was fired at a train while it was moving and the doors of the train opened via light sensory mechanics. To an observer inside the train, the doors would open simultaneously but, to an observer standing outside, they would be off-timed, and yet, this is not a contradiction. My teacher explained this as a proof of space being a relative concept of location between objects. How does this differ from primacy of conciousness or any other idea of subjectivism?

I doubt the student had any idea of what the postulate actually means.

It's like detailing how the theology of the Church leads to all sorts of practical results, such as loving one's neighbor and giving charity - and then throwing in as a comment that Ayn Rand thought charity was evil.

No. First of all, you would have to go through the same motions with Objectivism, detailing how it goes from its metaphysics and epistemology all the way down to its practical results. Second, that Ayn Rand thought charity was evil is true - in a specific context: charity as a categorical moral imperative, as a moral duty to sacrifice for the sake of others, is evil; but charity can also result from egoism, and in that context it is not a moral duty nor is it a sacrifice, and in this case Ayn Rand would not think it evil.

It appears to be a very similar situation with your classmate's quote from theoretical physics dumbed down to out-of-context nonsense.

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I doubt the student had any idea of what the postulate actually means.

It's like detailing how the theology of the Church leads to all sorts of practical results, such as loving one's neighbor and giving charity - and then throwing in as a comment that Ayn Rand thought charity was evil.

No. First of all, you would have to go through the same motions with Objectivism, detailing how it goes from its metaphysics and epistemology all the way down to its practical results. Second, that Ayn Rand thought charity was evil is true - in a specific context: charity as a categorical moral imperative, as a moral duty to sacrifice for the sake of others, is evil; but charity can also result from egoism, and in that context it is not a moral duty nor is it a sacrifice, and in this case Ayn Rand would not think it evil.

It appears to be a very similar situation with your classmate's quote from theoretical physics dumbed down to out-of-context nonsense.

You've got a good point; neither he, the teacher, nor I know the entire context of the statement and, therefore, we are all really arguing from ignorance.

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