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Clip"the photon's local frame / what a photon "experiences" is not a valid question under special relativity - observation, experience, and measurement cannot be divorced from matter, which in turn has mass, this means it cannot go the speed of light, which means it cannot be in the photon's frame . more, it means the photon cannot have a local frame because frames are inertial."

a gedanken that starts with an impossible scenario can generate any outcome with no reference to truth, logic or theory.

The delay is caused by the curvature of space-time, the geodesic of which is longer than the straight line between any two points in space.

In various places I think I have tried the patience of a number of scientific posters with this sort of discussion. The fact is I have still not managed to get my head round it.Mike asks a question to which I would really like to see an answer: "If light does not travel instantaneously ... in its own reference frame" What does it do? What does mainline science have to say about this?

Quote from: imatfaal a gedanken that starts with an impossible scenario can generate any outcome with no reference to truth, logic or theory. Didn’t Einstein start a gedanken by imagining himself keeping pace with light?

Quote from: MikeS The delay is caused by the curvature of space-time, the geodesic of which is longer than the straight line between any two points in space. I thought the definition of a geodesic was that it represents the shortest distance between two points in curved spacetime.

In various places I think I have tried the patience of a number of scientific posters with this sort of discussion. The fact is I have still not managed to get my head round it.Mike asks a question to which I would really like to see an answer: "If light does not travel instantaneously ... in its own reference frame" What does it do? What does mainline science have to say about this?Quote a gedanken that starts with an impossible scenario can generate any outcome with no reference to truth, logic or theory. Didn’t Einstein start a gedanken by imagining himself keeping pace with light? Quote The delay is caused by the curvature of space-time, the geodesic of which is longer than the straight line between any two points in space. I thought the definition of a geodesic was that it represents the shortest distance between two points in curved spacetime.

QuoteQuote The delay is caused by the curvature of space-time, the geodesic of which is longer than the straight line between any two points in space. I thought the definition of a geodesic was that it represents the shortest distance between two points in curved spacetime.Bill, yes you are quite right but a curved line between two points is longer than a straight line between the same two points. It is still the shortest distance between two points in curved space-time. That's the point I was trying to make.

Quote The delay is caused by the curvature of space-time, the geodesic of which is longer than the straight line between any two points in space. I thought the definition of a geodesic was that it represents the shortest distance between two points in curved spacetime.

imatfaalPlease correct me if I am wrong (didn't really need to ask did I) but I understand you to be saying that mainline science, including SR and GR has no views on what a photon experiences on the subjects of either, time or distance?

Without gravity and hence time there would be no curvature of space and the distance between the two points would be shorter.

You cannot talk about ‘Time’ without considering ‘Gravity’ as the two are intertwined in space-time.

Einstein showed us that gravity is the same as acceleration but to the best of my knowledge he did not elaborate upon that.

Acceleration is the rate of change of velocity with time. We normally think of this as a progressive change in distance covered, with time but it is equally valid to think of it as a change in the ‘going rate or dilation of time’ with distance.

Time gravitationally dilates near to a large mass.

Therefore time passes slower near to the Earths surface than it does further away. This difference is progressive. A way of visualizing this is to consider ‘the going rate of time’ or time dilation to be in shells around the Earth like layers of an onion. Each shell represents a particular time dilation factor with the greatest time dilation being closest to the Earth getting progressively less in each subsequent layer as you travel further from the Earth.

The Earth, like all objects is continually passing through space-time. If we think of these shells of time as continually collapsing on the Earth, each shell of time dilates as it approaches the Earths surface.

It is perhaps easiest to visualize it by considering space to be filled by something, say aether. This aether is continually being sucked into the Earth like a waterfall but all over the Earths surface . The aether may or may not exist, the important point is it carries shells of time with it and these shells of time dilate more as they approach the Earth. As shells of time dilate approaching the Earth so the Earth accelerates through these shells of time. This is where the acceleration comes from; it is an acceleration in time. All massive bodies produce a gravitational ‘field’ as they accelerate through time. The aforementioned also explains why bodies fall within a gravitational field. As the aether or shells of time fall upon the Earth so do other bodies that are within that sphere of influence. They are swept along with the changing rate of time dilation. As any object (mass) approaches the Earth (or any massive body), it enters shells of more and more dilated time. This reduces all of the useful energy of the object as entropy increases. The increased entropy represents a state of increased stability within the system. (When any two objects combine, time for them dilates, entropy increases and they reach a state of greater stability. For example a book on a table has more usable energy than the same book on the floor. The book on the floor is more stable as it can't fall off the table)

Gravity then is the Universes way of returning to its ground state, which ideally would be zero useable energy, near zero temperature, near zero passing time and near zero size. These conditions represent the Universes most stable configuration and these conditions are best met within a black hole.

Quote from: MikeS on 31/01/2012 14:06:32You cannot talk about ‘Time’ without considering ‘Gravity’ as the two are intertwined in space-time. of course you can. Gravity is an artefact of warped spacetime - but space time does not require gravity. Many theories rely on flat space - SR for one.QuoteEinstein showed us that gravity is the same as acceleration but to the best of my knowledge he did not elaborate upon that. Quite a lot of his work was based on the fact that in a local and small enough frame that acceleration and gravity were equivalent.[/color]QuoteAcceleration is the rate of change of velocity with time. We normally think of this as a progressive change in distance covered, with time but it is equally valid to think of it as a change in the ‘going rate or dilation of time’ with distance. Acceleration is the second time derivative of position - your first sentence had it spot on. Your second definition is dubious QuoteTime gravitationally dilates near to a large mass. Technically it is the gravitational potential Quote Therefore time passes slower near to the Earths surface than it does further away. This difference is progressive. A way of visualizing this is to consider ‘the going rate of time’ or time dilation to be in shells around the Earth like layers of an onion. Each shell represents a particular time dilation factor with the greatest time dilation being closest to the Earth getting progressively less in each subsequent layer as you travel further from the Earth. QuoteThe Earth, like all objects is continually passing through space-time. If we think of these shells of time as continually collapsing on the Earth, each shell of time dilates as it approaches the Earths surface. Nope - gonna have to explain that more.Quote It is perhaps easiest to visualize it by considering space to be filled by something, say aether. This aether is continually being sucked into the Earth like a waterfall but all over the Earths surface . The aether may or may not exist, the important point is it carries shells of time with it and these shells of time dilate more as they approach the Earth. As shells of time dilate approaching the Earth so the Earth accelerates through these shells of time. This is where the acceleration comes from; it is an acceleration in time. All massive bodies produce a gravitational ‘field’ as they accelerate through time. The aforementioned also explains why bodies fall within a gravitational field. As the aether or shells of time fall upon the Earth so do other bodies that are within that sphere of influence. They are swept along with the changing rate of time dilation. As any object (mass) approaches the Earth (or any massive body), it enters shells of more and more dilated time. This reduces all of the useful energy of the object as entropy increases. The increased entropy represents a state of increased stability within the system. (When any two objects combine, time for them dilates, entropy increases and they reach a state of greater stability. For example a book on a table has more usable energy than the same book on the floor. The book on the floor is more stable as it can't fall off the table) You might want to give some more concrete examples, be more specific and do some maths to back that upQuoteGravity then is the Universes way of returning to its ground state, which ideally would be zero useable energy, near zero temperature, near zero passing time and near zero size. These conditions represent the Universes most stable configuration and these conditions are best met within a black hole. Your conditions are not complementary; in a situation of zero gravitational potential where is the time dilation coming from? Near zero size would mean that any radiation is constrained to short wavelength, high frequency ...

Quote from: imatfaal on 31/01/2012 16:46:01Quote from: MikeS on 31/01/2012 14:06:32You cannot talk about ‘Time’ without considering ‘Gravity’ as the two are intertwined in space-time. of course you can. Gravity is an artefact of warped spacetime - but space time does not require gravity. Many theories rely on flat space - SR for one.QuoteWe know that time is affected by gravity or gravitational potential, if you like, so gravity has to be considered when talking about time. You say “gravity is an artifact of warped space-time” but I think this is like the chicken and the egg, which came first. In the normal universe, not a black hole, you can’t have gravity without time and you can’t have time without gravity. You say that “space-time does not require gravity” It does, without gravity time has no arrow. There is no space-time without gravity. No mass equals no gravity which is essentially the condition probably prevailing prior to the birth of the universe. Whether or not time existed prior to the birth of the Universe may be debatable but it probably did not.

Quote from: MikeS on 31/01/2012 14:06:32You cannot talk about ‘Time’ without considering ‘Gravity’ as the two are intertwined in space-time. of course you can. Gravity is an artefact of warped spacetime - but space time does not require gravity. Many theories rely on flat space - SR for one.QuoteWe know that time is affected by gravity or gravitational potential, if you like, so gravity has to be considered when talking about time. You say “gravity is an artifact of warped space-time” but I think this is like the chicken and the egg, which came first. In the normal universe, not a black hole, you can’t have gravity without time and you can’t have time without gravity. You say that “space-time does not require gravity” It does, without gravity time has no arrow. There is no space-time without gravity. No mass equals no gravity which is essentially the condition probably prevailing prior to the birth of the universe. Whether or not time existed prior to the birth of the Universe may be debatable but it probably did not.

We know that time is affected by gravity or gravitational potential, if you like, so gravity has to be considered when talking about time. You say “gravity is an artifact of warped space-time” but I think this is like the chicken and the egg, which came first. In the normal universe, not a black hole, you can’t have gravity without time and you can’t have time without gravity. You say that “space-time does not require gravity” It does, without gravity time has no arrow. There is no space-time without gravity. No mass equals no gravity which is essentially the condition probably prevailing prior to the birth of the universe. Whether or not time existed prior to the birth of the Universe may be debatable but it probably did not.