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Thread: Relativity

  1. #1

    Relativity

    Heres another good one for you:
    Galaxies travel through space, away from each other, and most galaxies travel at very high speeds. If time slows down to the traveler, or galaxy as it approaches the speed of light, and our galaxy is moving many times faster than another galaxy, would our galaxy be younger, given they were both formed at the same time? Would two people born at the same time, one was born here on earth and one born on a planet in a slower moving galaxy actually be different ages? and how would one determine what the "same time" is here in relation to another galaxy?

  2. #2
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    That's the problem (well, not real problem, but conceptual problem) with special relativity. If two individuals (let's call them Alice and Bob for simplicity) are traveling away from one another at relativistic speeds, then Alice thinks that Bob's clock is running slowly and that Bob has aged less than her, while Bob thinks the same about Alice. But as you pointed out, they can never actually meet and compare their data. If they want to meet, one or both of them will need to accelerate their ship back in the opposite direction. Because of that acceleration, the two points of view are not equal, and so they'll both agree on who should be older than the other. (If they both accelerate equally back towards the middle, they'll both agree that they should be the same age. So there would be no conflict in that event either.)

    Likewise, if we're looking at a galaxy 1 billion light-years away which appears to be just as old as ours, it's really 1 billion years older, because that's how long the light took to get there. Someone in that galaxy would observe our galaxy to be 2 billion light-years younger than their own.

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    Re: Relativity

    Quote Originally Posted by earthman2110
    Heres another good one for you:
    Galaxies travel through space, away from each other, and most galaxies travel at very high speeds. If time slows down to the traveler, or galaxy as it approaches the speed of light, and our galaxy is moving many times faster than another galaxy, would our galaxy be younger, given they were both formed at the same time? Would two people born at the same time, one was born here on earth and one born on a planet in a slower moving galaxy actually be different ages? and how would one determine what the "same time" is here in relation to another galaxy?

    There is no “time dilation” in galaxies that are moving faster than “c” relative to us. If there was, then their molecular vibration rate would shrink to zero, according to SR theory, and they would be frozen solid. But they aren’t frozen solid, because we can see them glowing.

    The “speed limit” and “time dilation” of SR theory was taken from Lorentz theory, and Lorentz based his theory on movement through fields, not just “relative motion”. Just “relative motion” can not slow down any clock or “time” or molecular vibration rate.

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    Quote Originally Posted by rwald
    Likewise, if we're looking at a galaxy 1 billion light-years away which appears to be just as old as ours, it's really 1 billion years older, because that's how long the light took to get there. Someone in that galaxy would observe our galaxy to be 2 billion light-years younger than their own.
    1 billion years younger than their own. That is classical 1842 Doppler theory.

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    Well, they would only see our galaxy being born when theirs was 2 billion years old. If they were calculating for distance, they would know that ours was really only 1 billion years younger, not 2, but that's the same as the fact that we "see" them to be the same age, but calculate them to be 1 billion years older.

    Now, about your first post. How could a galaxy be moving away from us faster than c? I thought that nothing could move faster than c. I know there are some circumstances under which an object can appear to move faster than c, but I thought those were just illusions set up by odd series of events. Also, I thought that it was relative motion that caused time dialation; if I see you moving at a speed v with respect to me, I think that every one second as measured by your clock is gamma seconds as measured by mine. Where do fields enter into this?

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    Quote Originally Posted by rwald
    Well, they would only see our galaxy being born when theirs was 2 billion years old. If they were calculating for distance, they would know that ours was really only 1 billion years younger, not 2, but that's the same as the fact that we "see" them to be the same age, but calculate them to be 1 billion years older.
    Ok, I see what you mean.

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    Quote Originally Posted by rwald
    Now, about your first post. How could a galaxy be moving away from us faster than c? I thought that nothing could move faster than c. I know there are some circumstances under which an object can appear to move faster than c, but I thought those were just illusions set up by odd series of events. Also, I thought that it was relative motion that caused time dialation; if I see you moving at a speed v with respect to me, I think that every one second as measured by your clock is gamma seconds as measured by mine. Where do fields enter into this?


    Well, it’s like this... there is a debate in astronomy about this. Some astronomers say they are NOT moving faster than c relative to us, while some say they ARE moving faster than c relative to us.

    I’ve figured out a way they could violate the “c” speed limit.

    That speed limit is based on Lorentz’s “motion through fields” idea. So, the speed limit might apply here on earth and inside our galaxy and inside other galaxies, because of all the gravity fields inside galaxies. But, if the most distant galaxies are NOT moving through fields, then there might not be any speed limit at all.

    See? Lorentz said it was the fields that put up the resistance to the movement of atoms and masses. That’s why he had atoms and physical things “shrinking” in their direction of motion.

    But if the distant galaxies are moving into empty space, free of strong fields, then they might not have a speed limit.

    Yes they are moving into the gravity fields of the galaxies that are out ahead of them, but those are the weak parts of the fields, and the fields of the forward galaxies (the ones most further away) might have a “sucking” effect, that pulls on the galaxies behind them.

    What started all of this motion, no one knows.

    I mean, in terms of physics they don’t know.

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    Actually, if I recall, Lorentz personally believed that a literal ether existed; it just so happened (according to Lorentz) that the ether would warp space and time using his now-famous equations. So, I'm not sure that the fact that Lorentz originally thought of his equations as applying to "motion through fields" necessarily means much.

    Personally, I don't like the idea that distant object could exceed c, even if they're beyond any local gravitational field. If that were true, there could be an observer who were sitting in between the two galaxies who would see neither galaxy moving greater than c (well, if the exact speeds were tweaked properly, etc.). If he sees everyone as moving less than c, then I don't see why the observers in the galaxies should see anything moving faster than c.

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    Quote Originally Posted by rwald
    Actually, if I recall, Lorentz personally believed that a literal ether existed; it just so happened (according to Lorentz) that the ether would warp space and time using his now-famous equations. So, I'm not sure that the fact that Lorentz originally thought of his equations as applying to "motion through fields" necessarily means much.
    It is quite interesting that his “ether” acted like a “field” and his “fields” acted like an “ether”. That’s why Einstein was able to use his equations.

    In Einstein’s 1911 theory, his gravitational fields acted like an “ether”.

    Quote Originally Posted by rwald
    Personally, I don't like the idea that distant object could exceed c, even if they're beyond any local gravitational field. If that were true, there could be an observer who were sitting in between the two galaxies who would see neither galaxy moving greater than c (well, if the exact speeds were tweaked properly, etc.). If he sees everyone as moving less than c, then I don't see why the observers in the galaxies should see anything moving faster than c.
    The further away they are, the faster they seem to move, relative to any observer.

    Newton called this “big bang” theory a “projectile impulse”.

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    Well, let's say that it appears that some distant galaxy appears to be moving away from us at 1.5c. An observer sitting between the two galaxies would see each receading at some speed less than 1.5c. If this speed is less than c, then when you add together the two velocities, it wouldn't exceed 1c, because of the velocity-sum equations. If the speed is still greater than c, then you could pick another observer between the middle observer and one galaxy, and continue doing so until you get some speed less than c, reducing this down to the first argument. I don't really see how any observer could see another galaxy to be moving away at speeds greater than c.

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    Quote Originally Posted by rwald
    Well, let's say....
    Well, the estimated speeds are based on their redshifts. Some people think the redshifts are due to distance only, something caused by the Compton Effect.

    Look, we’ve got a choice.... either they are all moving apart at rapid speeds, including speeds greater than c, or something is holding them in place, keeping them from collapsing due to all the gravitational pull of all of them. Either way, something unusual is going on, and it’s more than we can understand right now.

    This is the same problem that confronted Newton 350 years ago.

  12. #12
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    Quote Originally Posted by rwald
    I don't really see how any observer could see another galaxy to be moving away at speeds greater than c.
    Here, read this. They tell you how it can happen. The light starts out slow relative to us and it gradually speeds up:

    LINK

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    Earthman, it isn't really correct to say galaxies are traveling away from each other. The observed motion in the redshift is actually the space between the galaxies expanding. So this isn't a relativity, nor is it a twins paradox issue.

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    Quote Originally Posted by russ_watters
    Earthman, it isn't really correct to say galaxies are traveling away from each other. The observed motion in the redshift is actually the space between the galaxies expanding. So this isn't a relativity, nor is it a twins paradox issue.
    “Expanding space” is absurd. Things move. Galaxies move through space. Distance changes.

    The idea that the galaxies are “stationary” and the “space between them” expands is a silly superstition. That’s like medieval hocus pocus, magic.

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    Thanks for the laugh Sam, honestly.

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    Quote Originally Posted by Musashi
    Thanks for the laugh Sam, honestly.
    Why don’t you tell us what “space” is and how it “expands”. Does it “stretch”, or is “new space” just added to the old space?

    Where do we get this “new space”? Who puts it between the distant galaxies?

    Oh, and can you link us to a scientific paper that tells us where this “new space” comes from?

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    Re: Relativity

    Quote Originally Posted by earthman2110
    If time slows down to the traveler, or galaxy as it approaches the speed of light, [...]
    Keep in mind that time remains constant for any traveler relative to herself. So if I've taken off from the Earth in a rocket and am approaching c, I cannot detect any alteration of my clock. On the other hand, to the folks back on Earth my transmitted voice is becoming increasingly slower. In other words, they detect my clock slowing down... and I detect their clock speeding up.

    If I then accelerate back to the Earth I will find once I've returned that I'm younger than my twin. This is call the twin paradox. The key to the aging asymmetry is my nonuniform (or accelerating) motion versus the uniform motion of my twin on Earth (which is accelerating to the extent that circular motion (of the Earth around the Sun) is inherently an acceleration, but for practical purposes of the example is uniform compared to my rocket approaching c). Notice that this is different from the scenario you describe.

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    Re: Relativity

    Quote Originally Posted by Ian Goddard
    Quote Originally Posted by earthman2110
    If time slows down to the traveler, or galaxy as it approaches the speed of light, [...]
    Keep in mind that time remains constant for any traveler relative to herself. So if I've taken off from the Earth in a rocket and am approaching c, I cannot detect any alteration of my clock.

    If you accelerate to near c, I think you would notice some high g forces.

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    The g forces would only depend on the magnitude of your acceleration. If you accelerated at 32 m/s^2 for years until you were traveling near c, you still would feel just the same as you would on Earth. Of course, if you accelerated to near c very quickly, then the magnitude of the acceleration would be higher, and that would cause you to feel high g forces.

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    Re: Relativity

    Quote Originally Posted by Sam5
    Quote Originally Posted by Ian Goddard
    Quote Originally Posted by earthman2110
    If time slows down to the traveler, or galaxy as it approaches the speed of light, [...]
    Keep in mind that time remains constant for any traveler relative to herself. So if I've taken off from the Earth in a rocket and am approaching c, I cannot detect any alteration of my clock.
    If you accelerate to near c, I think you would notice some high g forces.
    Yeah, okay... and nothing I said implied otherwise.

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    Quote Originally Posted by Musashi
    Thanks for the laugh Sam, honestly.
    Oy. Sometimes I wonder why we bother with him, but every now and then we get a gem like that. That makes it worthwhile.

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    russ_watters, Musashi,

    Question #1:

    Here are two questions for you guys. You say that the galaxies “don’t move” but that “the space in between the galaxies expands”. So, question # 1 is, how does the “space expand”? Does the old space “stretch” or is “new space” added to the “old space”? If so, where does the “new space” come from? Give us some science papers that explain how this works.

    Question #2:

    Here’s the situation. It’s very simple:

    An atomic clock ticks slow in a valley and fast on a mountain.

    An atomic clock in a valley will measure “c” as the speed of a horizontal beam of light in a valley.

    An atomic clock on a mountain will measure “c” as the speed of a horizontal beam of light on a mountain.

    This means the speed of the light beam in a valley is moving slower than the speed of the light beam on the mountain.

    This means the speed of light is variable at different places in a gravity field, and this is what Einstein said in his 1911 paper and his 1916 book.

    So why is this such a big secret in science today?

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    Quote Originally Posted by Sam5
    russ_watters, Musashi,

    Question #1:

    Here are two questions for you guys. You say that the galaxies “don’t move” but that “the space in between the galaxies expands”. So, question # 1 is, how does the “space expand”? Does the old space “stretch” or is “new space” added to the “old space”? If so, where does the “new space” come from? Give us some science papers that explain how this works.
    This is actually a very good question. I think it's more philosophical in asking what space really "is," but either way we still observe expansion and distance between galaxies, so there must be something there.

    Quote Originally Posted by Sam5
    Question #2:

    Here’s the situation. It’s very simple:

    An atomic clock ticks slow in a valley and fast on a mountain.

    An atomic clock in a valley will measure “c” as the speed of a horizontal beam of light in a valley.

    An atomic clock on a mountain will measure “c” as the speed of a horizontal beam of light on a mountain.

    This means the speed of the light beam in a valley is moving slower than the speed of the light beam on the mountain.

    This means the speed of light is variable at different places in a gravity field, and this is what Einstein said in his 1911 paper and his 1916 book.

    So why is this such a big secret in science today?
    I answered this elsewhere.

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    Quote Originally Posted by Normandy6644
    Quote Originally Posted by Sam5
    russ_watters, Musashi,

    Question #1:

    Here are two questions for you guys. You say that the galaxies “don’t move” but that “the space in between the galaxies expands”. So, question # 1 is, how does the “space expand”? Does the old space “stretch” or is “new space” added to the “old space”? If so, where does the “new space” come from? Give us some science papers that explain how this works.
    This is actually a very good question. I think it's more philosophical in asking what space really "is," but either way we still observe expansion and distance between galaxies, so there must be something there.

    Well, thank you very much.

    I maintain that the “expansion of space” was just a philosophical term that was pulled out of thin air so as to protect Einstein’s “speed limit of ‘c’” claim in his 1905 paper.

    What we actually seem to have is galaxies MOVING THROUGH SPACE at faster than “c”, and if that is the case, that would suggest that Einstein’s 1905 “speed limit” (which was actually Lorentz’s speed limit) was wrong.

    So, anyone who claims “space is expanding” should be able to explain exactly “how” space is expanding, in terms of physics, or they should just shut up about it.

    If they can’t explain it physically, in terms of physics, then it is nothing more than a belief in either “magic” or “miracles”, with no scientific basis whatsoever.

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    Quote Originally Posted by Normandy6644
    This is actually a very good question.

    My “belief” is actually a very good scientifically based compromise.

    I say the “speed limit” applies to motion of matter through “fields”, but it does not apply to motion of matter in deep space because that motion is not “through fields” but through “empty space”. This is based on Lorentz theory. The reason why Einstein and Lorentz probably didn’t figure this out was because they did not know of any large objects like galaxies that were traveling so fast.

    If they were alive today I think they would agree with my point of view, because today they would know about the high redshifts of the distant galaxies. They did not know about such a thing in 1905.

  26. #26
    Quote Originally Posted by Sam5
    [Snip!]So, anyone who claims “space is expanding” should be able to explain exactly “how” space is expanding, in terms of physics, or they should just shut up about it.

    If they can’t explain it physically, in terms of physics, then it is nothing more than a belief in either “magic” or “miracles”, with no scientific basis whatsoever.
    The expansion of spacetime was first explained in Einstein's 1917 paper, Cosmological Considerations on the General Theory of Relativity. It makes use of the 1915 paper that you never discuss because the math is so obviously beyond you. The expansion of spacetime is a direct consequence of Einstein's equations.

    Suggestion: learn the math, then get Misner, Thorne and Wheeler's Gravitation and read up on cosmology. The book is a little dated because they lean towards a closed and bounded universe. And so it goes...

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    Quote Originally Posted by Celestial Mechanic
    The expansion of spacetime was first explained in Einstein's 1917 paper, Cosmological Considerations on the General Theory of Relativity.
    His 1917 paper is the one with the cosmological constant in it and curved universal space. He had to withdraw that paper when Hubble discovered the redshifts, and Einstein did that in a paper he wrote with de Sitter in 1932. I’ve got a copy of both papers. Back in 1917 Einstein thought all the distant stars were “fixed” and he doesn’t have an expanding universe or “expanding space” in that paper. When he removed the cosmological constant and the curve space in 1932, the galaxies were free to move through space, which is something he tried to avoid with his 1916 paper.

    There is no such thing as “expanding space”.

    He said in 1932:

    “There is no direct observational evidence for the curvature, the only directly observed data being the mean density and the expansion, which latter proves that the actual universe corresponds to the non-statical case. It is therefore clear that from the direct data of observation we can derive neither the sign nor the value of the curvature, and the question arises whether it is possible to represent the observed facts without introducing a curvature at all.”

    “Although, therefore, the density corresponding to the assumption of zero curvature and to the coefficient of expansion may perhaps be on the high side, it certainly is of the correct order of magnitude, and we must conclude that at the present time it is possible to represent the facts without assuming a curvature of three-dimensional space. The curvature is, however, essentially determinable, and an increase in the precision of the data derived from observations will enable us in the future to fix its sign and to determine its value.”


    And in the 1932 paper he has the galaxies moving apart by means of motion, with no “expansion of space”. He gives the formula of the motion of the galaxies to be:

    h = 500 km./sec. per 10^6 parsecs.

    And of course Hubble’s own calculations have the galaxies moving through too.

    I’ve got a 1959 University astronomy book that has the galaxies moving through space.

    The “expansion of space” idea only started being promoted when the high-z galaxies were discovered in the 1960s-‘90s, and that indicated they were moving faster than “c” relative to the earth. So, in the continuing effort to try to salvage Einstein’s 1905 “speed limit” prediction, all of a sudden we started hearing about “the expansion of space”, with the galaxies “not moving” at all! But nobody can give any scientific explanation of it, because it’s nonsense. It’s one of the greatest con-jobs of modern cosmology.

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    Re: Relativity

    Quote Originally Posted by Sam5
    Quote Originally Posted by earthman2110
    Heres another good one for you:
    Galaxies travel through space, away from each other, and most galaxies travel at very high speeds. If time slows down to the traveler, or galaxy as it approaches the speed of light, and our galaxy is moving many times faster than another galaxy, would our galaxy be younger, given they were both formed at the same time? Would two people born at the same time, one was born here on earth and one born on a planet in a slower moving galaxy actually be different ages? and how would one determine what the "same time" is here in relation to another galaxy?

    There is no “time dilation” in galaxies that are moving faster than “c” relative to us. If there was, then their molecular vibration rate would shrink to zero, according to SR theory, and they would be frozen solid. But they aren’t frozen solid, because we can see them glowing.

    The “speed limit” and “time dilation” of SR theory was taken from Lorentz theory, and Lorentz based his theory on movement through fields, not just “relative motion”. Just “relative motion” can not slow down any clock or “time” or molecular vibration rate.
    Drivel. [-X

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    Re: Relativity

    Quote Originally Posted by Sam5
    There is no “time dilation” in galaxies that are moving faster than “c” relative to us. If there was, then their molecular vibration rate would shrink to zero, according to SR theory, and they would be frozen solid. But they aren’t frozen solid, because we can see them glowing.
    Um, we wouldn't be able to see a galaxy that recedes at superluminal speed because its light never reaches us. Thus we can't "see them glowing."



    And for something different:
    Quote Originally Posted by rwald
    If you accelerated at 32 m/s^2 for years until you were traveling near c, you still would feel just the same as you would on Earth.
    The numbers are wrong, Earth surface gravity is 9.81 m/s^2 (or 35.30 km/h/s).

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    Re: Relativity

    Quote Originally Posted by Andreas
    And for something different:
    Quote Originally Posted by rwald
    If you accelerated at 32 m/s^2 for years until you were traveling near c, you still would feel just the same as you would on Earth.
    The numbers are wrong, Earth surface gravity is 9.81 m/s^2 (or 35.30 km/h/s).
    I'm sure he meant 32 feet /s^2.

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