It's a question that you can't really answer, because frames of reference become meaningless at exactly at c. If the universe is zero thickness in your direction of travel, and all other clocks have slowed to a stop, what meaning does speed have in a time-stopped, less-than-paper-thin universe? By having infinite mass relative to the rest of the universe, you'd probably be cut off inside some mathematically degenerate infinite black hole anyway. Perhaps you'd have already converted the entire remainder of the universe into energy in order to power your mad light-speed dash, so Ship B would be toast anyway
Maybe QM, if it can be used here at all (and I'm just wildly guessing about all of this), would tell you the the Universe can only be said to be 0 thickness +/- a Planck length, and that clocks are only stopped +/- a Planck time -- but I don't know if you can extract anything meaningful out of any of that.
This isn't entirely true... A photon can experience the effect of other photons (persuming gravity acts by photons) at a direction orthaganol to it movement. When the ship is moving slower than c you can see (assuming you are in its light cone) the ship at 90 degrees from you and if it remains moving at 90 degrees you can measure a velocity from a "rest frame" in that direction...
I completely agree with all of that, however, string theory isn't based upon a working metric like black holes are. Hawking readily admits that until black holes are proven phenomena all of what he does in his mental flexing is a what if situation that is based upon known working physics. String theory doesn't even have that. It has existed for the better part of two decades more or less and there are no predictions of physical phenomena...
I really have no idea, but are not the physical phenomena of strings manifested in the quantum world, which we can limitedly play with, abit like, you cannot see it, but you can feel the effects? is it not just a question of time before we become competent enough to play with the physical fundamentals of quantum elements
It is math and should be treated as such. Placing any significant weight on it as the solution ot the universe and all of life (42) is simply stupid....
is it not just resonances of pure energy, I dont know if thats hard to swallow, even if it might take us 50 years to prove it.
This isn't entirely true... A photon can experience the effect of other photons (persuming gravity acts by photons) at a direction orthaganol to it movement. When the ship is moving slower than c you can see (assuming you are in its light cone) the ship at 90 degrees from you and if it remains moving at 90 degrees you can measure a velocity from a "rest frame" in that direction...
If you talk about photons interacting, those interactions are not described in reference to any frame of reference belonging to any of the photons. The only thing that I said made no sense was trying to describe events and objects in the outside world from within a light-speed frame of reference itself. As originally asked, if you propose that Ship A is travelling at the speed of light, and then ask what an observer on Ship A would observe about anything, I still contend that relativity allows no meaningful answer here.
I was interested in seeing what the formula produced. Could you tell me what the answers are at 0.99 c, and if poss, what the answers are at 100%c, assuming no div by 0, or other strangities.
First, you'll have to be more specific. Which of the these things do you mean:
As described from some arbitrary rest frame, there are four ships, each travelling 0.99c, two, A and B, going in the same direction, another ship, X (I don't want to call it C), moving at a right angle to the trajectory of A and B, and another ship, Y, going in the opposite direction as A and B...
...or...
Ship A (which, to an observer on Ship A is at rest, even if you say it's at 0.99c in some other frame), sees three ships traveling away from it, each at 0.99c, in three of four cardinal directions.
I really have no idea, but are not the physical phenomena of strings manifested in the quantum world, which we can limitedly play with, abit like, you cannot see it, but you can feel the effects? is it not just a question of time before we become competent enough to play with the physical fundamentals of quantum elements
is it not just resonances of pure energy, I dont know if thats hard to swallow, even if it might take us 50 years to prove it.
No string theory is just mathematical tomfoolery at this point... it makes no testable predictions that can be extended into quantum....
If you talk about photons interacting, those interactions are not described in reference to any frame of reference belonging to any of the photons. The only thing that I said made no sense was trying to describe events and objects in the outside world from within a light-speed frame of reference itself. As originally asked, if you propose that Ship A is travelling at the speed of light, and then ask what an observer on Ship A would observe about anything, I still contend that relativity allows no meaningful answer here.
My reference to photons interacting was just an example of the fact that in the photon frame there are events that are observable. The only dimension that is affected by relativistic contraction is the direction in which the frame is traveling.....
what I ment, was your 'or' scenario, how fast would someone in the ship travelling at .99c measure ships travelling at .99c traveling away at 90 and 180 degrees.
I guess its pretty obvious that the ship travelling at 0 deg (ie parallel) would measure a relative speed of 0.
What does happen if you put the numbers of 100% c into the equation you use, do you get an answer, or do you get mathmatically invalid expression (like div by 0)?
My reference to photons interacting was just an example of the fact that in the photon frame there are events that are observable. The only dimension that is affected by relativistic contraction is the direction in which the frame is traveling.....
The relativistic contraction may only be in one direction, but with all of past and future time squashed down to an infinitely thin plane at a right angle to the observer's light speed motion, what kind of observable events can you possibly have?
An important thing to remember about relativistic contraction: the observed extent of a contracted object is composed of points along that object that are not simultaneous in that object's frame. If you observe our galaxy squished seven times smaller in one direction as you fly by at 0.95c, you observe (not "see", but deduce from what you compute after adjusting what you see for light travel time) one side of the galaxy nearly 100,000 years older than the other side. Your speed essentially exchanges part of the spacial extent of the galaxy for a temporal extent.
At light speed itself, the rest of the universe would have zero extent in one direction with all of time squeezed into that extent.
what I ment, was your 'or' scenario, how fast would someone in the ship travelling at .99c measure ships travelling at .99c traveling away at 90 and 180 degrees.
I hate to be a pain about this, because I'm pretty sure I know what you're really asking, but you have to ask the question correctly in order to understand the answer. You say that what you meant was my "or" scenario, the second scenario I gave, but the way you've rephrased the conditions of that scenario, you're implying an unstated arbitrary rest frame, which is more like my first scenario.
If you say a ship is travelling 0.99c relative to another ship, the answer is implicit: 0.99c, what you just said the relative speed was. Try to re-ask your question, making it completely clear the reference frame for each stated velocity, and the reference frame or frames for the desired answers.
So as to not hold out on you entirely...
The relevant math for solving these kinds of problems involves the Lorentz transform, sqrt(1 - v^2) ("Square root of the quantity 1 minus v squared"), where v is stated as a fraction of the speed of light.
When v = 1, the speed of light, the transform factor is 0. When you're multiplying by this factor, equations don't blow up, but they do produce non-sensical answers like physical objects with zero length. There are places where you do have to divide by the transform, however, like computing the mass of a moving object: m = m0 / sqrt(1 - v^2), where m0 is the "rest mass" of the object. This is why mass, and the energy to keep pushing faster, approaches infinity as v approaches c.
You'll also end up dividing by zero when you try to compute the time on a clock traveling at c. If you go over v = 1, you'll then be trying to take square roots of negative numbers, so you'll have a problem regardless of whether you wish to multiply or divide by this factor.
Comments
Originally posted by shetline
It's a question that you can't really answer, because frames of reference become meaningless at exactly at c. If the universe is zero thickness in your direction of travel, and all other clocks have slowed to a stop, what meaning does speed have in a time-stopped, less-than-paper-thin universe? By having infinite mass relative to the rest of the universe, you'd probably be cut off inside some mathematically degenerate infinite black hole anyway. Perhaps you'd have already converted the entire remainder of the universe into energy in order to power your mad light-speed dash, so Ship B would be toast anyway
Maybe QM, if it can be used here at all (and I'm just wildly guessing about all of this), would tell you the the Universe can only be said to be 0 thickness +/- a Planck length, and that clocks are only stopped +/- a Planck time -- but I don't know if you can extract anything meaningful out of any of that.
This isn't entirely true... A photon can experience the effect of other photons (persuming gravity acts by photons) at a direction orthaganol to it movement. When the ship is moving slower than c you can see (assuming you are in its light cone) the ship at 90 degrees from you and if it remains moving at 90 degrees you can measure a velocity from a "rest frame" in that direction...
I completely agree with all of that, however, string theory isn't based upon a working metric like black holes are. Hawking readily admits that until black holes are proven phenomena all of what he does in his mental flexing is a what if situation that is based upon known working physics. String theory doesn't even have that. It has existed for the better part of two decades more or less and there are no predictions of physical phenomena...
I really have no idea, but are not the physical phenomena of strings manifested in the quantum world, which we can limitedly play with, abit like, you cannot see it, but you can feel the effects? is it not just a question of time before we become competent enough to play with the physical fundamentals of quantum elements
It is math and should be treated as such. Placing any significant weight on it as the solution ot the universe and all of life (42) is simply stupid....
is it not just resonances of pure energy, I dont know if thats hard to swallow, even if it might take us 50 years to prove it.
Originally posted by billybobsky
This isn't entirely true... A photon can experience the effect of other photons (persuming gravity acts by photons) at a direction orthaganol to it movement. When the ship is moving slower than c you can see (assuming you are in its light cone) the ship at 90 degrees from you and if it remains moving at 90 degrees you can measure a velocity from a "rest frame" in that direction...
If you talk about photons interacting, those interactions are not described in reference to any frame of reference belonging to any of the photons. The only thing that I said made no sense was trying to describe events and objects in the outside world from within a light-speed frame of reference itself. As originally asked, if you propose that Ship A is travelling at the speed of light, and then ask what an observer on Ship A would observe about anything, I still contend that relativity allows no meaningful answer here.
Originally posted by MarcUK
I was interested in seeing what the formula produced. Could you tell me what the answers are at 0.99 c, and if poss, what the answers are at 100%c, assuming no div by 0, or other strangities.
First, you'll have to be more specific. Which of the these things do you mean:
As described from some arbitrary rest frame, there are four ships, each travelling 0.99c, two, A and B, going in the same direction, another ship, X (I don't want to call it C), moving at a right angle to the trajectory of A and B, and another ship, Y, going in the opposite direction as A and B...
...or...
Ship A (which, to an observer on Ship A is at rest, even if you say it's at 0.99c in some other frame), sees three ships traveling away from it, each at 0.99c, in three of four cardinal directions.
Quote:
Originally posted by billybobsky
I really have no idea, but are not the physical phenomena of strings manifested in the quantum world, which we can limitedly play with, abit like, you cannot see it, but you can feel the effects? is it not just a question of time before we become competent enough to play with the physical fundamentals of quantum elements
is it not just resonances of pure energy, I dont know if thats hard to swallow, even if it might take us 50 years to prove it.
No string theory is just mathematical tomfoolery at this point... it makes no testable predictions that can be extended into quantum....
Originally posted by shetline
If you talk about photons interacting, those interactions are not described in reference to any frame of reference belonging to any of the photons. The only thing that I said made no sense was trying to describe events and objects in the outside world from within a light-speed frame of reference itself. As originally asked, if you propose that Ship A is travelling at the speed of light, and then ask what an observer on Ship A would observe about anything, I still contend that relativity allows no meaningful answer here.
My reference to photons interacting was just an example of the fact that in the photon frame there are events that are observable. The only dimension that is affected by relativistic contraction is the direction in which the frame is traveling.....
what I ment, was your 'or' scenario, how fast would someone in the ship travelling at .99c measure ships travelling at .99c traveling away at 90 and 180 degrees.
I guess its pretty obvious that the ship travelling at 0 deg (ie parallel) would measure a relative speed of 0.
What does happen if you put the numbers of 100% c into the equation you use, do you get an answer, or do you get mathmatically invalid expression (like div by 0)?
Originally posted by billybobsky
My reference to photons interacting was just an example of the fact that in the photon frame there are events that are observable. The only dimension that is affected by relativistic contraction is the direction in which the frame is traveling.....
The relativistic contraction may only be in one direction, but with all of past and future time squashed down to an infinitely thin plane at a right angle to the observer's light speed motion, what kind of observable events can you possibly have?
An important thing to remember about relativistic contraction: the observed extent of a contracted object is composed of points along that object that are not simultaneous in that object's frame. If you observe our galaxy squished seven times smaller in one direction as you fly by at 0.95c, you observe (not "see", but deduce from what you compute after adjusting what you see for light travel time) one side of the galaxy nearly 100,000 years older than the other side. Your speed essentially exchanges part of the spacial extent of the galaxy for a temporal extent.
At light speed itself, the rest of the universe would have zero extent in one direction with all of time squeezed into that extent.
Originally posted by MarcUK
shet,
what I ment, was your 'or' scenario, how fast would someone in the ship travelling at .99c measure ships travelling at .99c traveling away at 90 and 180 degrees.
I hate to be a pain about this, because I'm pretty sure I know what you're really asking, but you have to ask the question correctly in order to understand the answer. You say that what you meant was my "or" scenario, the second scenario I gave, but the way you've rephrased the conditions of that scenario, you're implying an unstated arbitrary rest frame, which is more like my first scenario.
If you say a ship is travelling 0.99c relative to another ship, the answer is implicit: 0.99c, what you just said the relative speed was. Try to re-ask your question, making it completely clear the reference frame for each stated velocity, and the reference frame or frames for the desired answers.
So as to not hold out on you entirely...
The relevant math for solving these kinds of problems involves the Lorentz transform, sqrt(1 - v^2) ("Square root of the quantity 1 minus v squared"), where v is stated as a fraction of the speed of light.
When v = 1, the speed of light, the transform factor is 0. When you're multiplying by this factor, equations don't blow up, but they do produce non-sensical answers like physical objects with zero length. There are places where you do have to divide by the transform, however, like computing the mass of a moving object: m = m0 / sqrt(1 - v^2), where m0 is the "rest mass" of the object. This is why mass, and the energy to keep pushing faster, approaches infinity as v approaches c.
You'll also end up dividing by zero when you try to compute the time on a clock traveling at c. If you go over v = 1, you'll then be trying to take square roots of negative numbers, so you'll have a problem regardless of whether you wish to multiply or divide by this factor.
thanks again