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Now we're at the heart of the matter. You're discussing metaphysics behind special relativity. That's a perfectly valid and interesting area, but it's not a matter for this science forum. If we were a philosophy forum, I'd say go at it!We had some interesting discussions here, but unless you'd like to discuss science, I'll have to ask you again to keep it to "new theories."
If you were on the retrieval team, you would know that the observed length of 10 meters, from earth's frame, was not its true length, in its own frame. You would not send out a shuttle with a 10 meter bay to retrieve it.
.. Einstein endorsed a form of idealism when he said that there is no reality independent of observation/measurement.If one is not allowed to disagree with that, then SR has become a realism- intolerant dogma in favor of SR's version of classical idealism.How about you? (Edit; anyone.) Are you an idealist or a realist. (Rhetorical question. Edit: lets make it a “real” question.) Does the falling tree make a sound without an observer to hear it?
My argument here simply questions how "real" length contraction is. Does a fast moving ship make stars move closer together? No, but its clock will "tick" more slowly the faster it flies, and its occupants will probably age more slowly.Do objects have shapes and lengths independent of how they are measured? Yes, there is a "real cosmos with real objects" in it, but they may well appear contracted from very fast fly-by frames.Can you really " fit the probe (very briefly) entirely within the shuttle's cargo bay?"No.Let's make the velocity of the probe relative to earth specific at 86.6 % of 'c.' If the "contracted length" as measured from earth is 10 meters, as established, it will then be 20 meters in its own frame and as measured from the shuttle once it enters that frame, at rest with the probe. A 20 meter probe will not fit into a 10 meter cargo bay, period, no matter how "briefly." Sorry.
My probe example intended to put some meat on the bones of the question, "What is real?" as a practical application, once we achieve relativistic speeds in space travel, of course. (See quote below.)The retrieval team must know the "real length" of the probe in order to send out a shuttle with a large enough cargo bay. Obviously the shuttle must "come alongside" the probe, matching velocities, at rest with the probe to capture it. (The conjectures about colliding with the probe would be the result of a very poorly planned mission!)Our cargo bay, as stated, is 10 meters. The "contracted length" of the probe, as seen from Earth's frame appears to be 10 meters. The point of the whole exercise was that 10 meters is not the probes *real length*, so sending out the above shuttle would be very stupid, because the probe is *really* longer than 10 meters. So there is your functional definition of "What is real?"
QuoteAnother example is the observed lifetime of muons in motion and thus their range of action, which is much higher than that of muons at low velocities. In the proper frame of the atmosphere, this is explained by the time dilation of the moving muons. However, in the proper frame of the muons their lifetime is unchanged, but the atmosphere is contracted so that even their small range is sufficient to reach the surface of earth.Essentially this argues that, because of “time dilation” (their rate of decay slows down at higher velocity), these mouns “live longer” than expected of lower velocity muons, and since length contraction is the math reciprocal of time dilation, for those muons “the atmosphere is contracted." From “the frame” of the whole picture however (earth and incoming muons) , there is no contracting of the atmosphere around each muon. “For a muon” does not change the atmospheric science of its thickness/depth.
Another example is the observed lifetime of muons in motion and thus their range of action, which is much higher than that of muons at low velocities. In the proper frame of the atmosphere, this is explained by the time dilation of the moving muons. However, in the proper frame of the muons their lifetime is unchanged, but the atmosphere is contracted so that even their small range is sufficient to reach the surface of earth.
My argument here simply questions how "real" length contraction is. Does a fast moving ship make stars move closer together? No, but its clock will "tick" more slowly the faster it flies, and its occupants will probably age more slowly.
Do objects have shapes and lengths independent of how they are measured? Yes, there is a "real cosmos with real objects" in it, but they may well appear contracted from very fast fly-by frames.Can you really " fit the probe (very briefly) entirely within the shuttle's cargo bay?"No.Let's make the velocity of the probe relative to earth specific at 86.6 % of 'c.' If the "contracted length" as measured from earth is 10 meters, as established, it will then be 20 meters in its own frame and as measured from the shuttle once it enters that frame, at rest with the probe. A 20 meter probe will not fit into a 10 meter cargo bay, period, no matter how "briefly." Sorry.
It is difficult to see how a thought experimental practical application of "length contraction"... my "probe retrieval project"... is considered metaphysics rather than the applied physics of length contraction.Of course the background contrast of Einstein's version of idealism with realism is philosophy, but my question, in that context, remains a real challenge to length contraction advocates:"Does Earth change shapes with every possible different perspective viewing it. I can't believe that you (edit; anyone) believe(s) that!"
Me, post 131, Length contraction thread in Physics section:/snipped
.. Einstein endorsed a form of idealism when he said that there is no reality independent of observation/measurement.If one is not allowed to disagree with that, then SR has become a realism- intolerant dogma in favor of SR's version of classical idealism.
Let's keep it on the topic without such irrelevant distractions, please.Earth does not change shapes to accommodate all varieties of observational points of view. Let us keep that fact in mind in this discussion.
Let us keep that fact in mind in this discussion.
Our cargo bay, as stated, is 10 meters. The "contracted length" of the probe, as seen from Earth's frame appears to be 10 meters. The point of the whole exercise was that 10 meters is not the probes *real length*, so sending out the above shuttle would be very stupid, because the probe is *really* longer than 10 meters. So there is your functional definition of "What is real?"
But it is a definition - that a) is not needed because the concept of reality as you define it is not important for the mathematical model and b) when the probe is moving very quickly I could get it in the open-ended shuttle bay at rest (with arbitrarily quick closing doors) . b) does not in my mind, challenge the "reality" of the probe being longer than 10m in it's rest frame - but it shows that differentiation between real and apparent are unimportant, dangerous, and misleading.
Old Guy, I'm not sure what you want me to reply to.
Essentially this argues that, because of “time dilation” (their rate of decay slows down at higher velocity), these mouns “live longer” than expected of lower velocity muons, and since length contraction is the math reciprocal of time dilation, for those muons “the atmosphere is contracted." From “the frame” of the whole picture however (earth and incoming muons) , there is no contracting of the atmosphere around each muon. “For a muon” does not change the atmospheric science of its thickness/depth.
You cannot have a rest frame which encompasses two objects with relative velocities.
Clocks only tick slower when viewed from another frame! And the fact that the earth bound observers see the space clocks as ticking slowly does not explain how the spacemen (who measure no dilation on their own clocks) reach alpha centauri in less than 4.37 years again according to the spacemen
Quote Do objects have shapes and lengths independent of how they are measured? Yes, there is a "real cosmos with real objects" in it, but they may well appear contracted from very fast fly-by frames. Can you really " fit the probe (very briefly) entirely within the shuttle's cargo bay?" No. Let's make the velocity of the probe relative to earth specific at 86.6 % of 'c.' If the "contracted length" as measured from earth is 10 meters, as established, it will then be 20 meters in its own frame and as measured from the shuttle once it enters that frame, at rest with the probe. A 20 meter probe will not fit into a 10 meter cargo bay, period, no matter how "briefly." Sorry.You:Quote The whole point of the corollary thought experiment is that the shuttle bay allows the probe in without matching velocity ie it is not in the rest frame of the probe - there is a high relative velocity; and then the probe will fit in! No, the whole point of my thought experiment was a practical (future) application of length contraction theory illustrating the difference between the probe's appearance as measured from earth and its real, actual length as measured from at rest with it, which is a requirement for retrieval of any object in space.imatfaal:Quote Can you just confirm to me whether you agree that (with arbitrarily fast doors) a shuttle bay with doors at front and back could hold the probe moving with relativistic velocity compared to and observed by the shuttle at rest?No. Retrieval requires being at rest with the probe. The shuttle cargo bay is 10 meters long. The probe is 20 meters long. It will not fit.
Do objects have shapes and lengths independent of how they are measured? Yes, there is a "real cosmos with real objects" in it, but they may well appear contracted from very fast fly-by frames. Can you really " fit the probe (very briefly) entirely within the shuttle's cargo bay?" No. Let's make the velocity of the probe relative to earth specific at 86.6 % of 'c.' If the "contracted length" as measured from earth is 10 meters, as established, it will then be 20 meters in its own frame and as measured from the shuttle once it enters that frame, at rest with the probe. A 20 meter probe will not fit into a 10 meter cargo bay, period, no matter how "briefly." Sorry.
The whole point of the corollary thought experiment is that the shuttle bay allows the probe in without matching velocity ie it is not in the rest frame of the probe - there is a high relative velocity; and then the probe will fit in!
Can you just confirm to me whether you agree that (with arbitrarily fast doors) a shuttle bay with doors at front and back could hold the probe moving with relativistic velocity compared to and observed by the shuttle at rest?
JP:QuoteOld Guy, I'm not sure what you want me to reply to.At this point I would settle for one straight answer from you.Do you believe that Earth changes shape?
Does it acquire a very contracted diameter *as observed*( in the direction of travel) by a relativistic fly- by frame?
Would it change into 1000 different shapes as 1000 different "frames" flew by in 1000 different directions at 1000 different velocities?
Old Guy,Well, since science deals with predicting measurements, and you want me to commit to predicting something beyond the realm of measurements I'm going to have to bow out and leave this one to metaphysics.
For the benefit of any newcomers to this thread or anyone wondering how/why it died...
Does Earth change shape?...
If so, what force is applied, according to the laws of physics, to make a large solid physical object drastically change shape?
Will an “alien probe” approaching Earth at 86.6 % of ‘c’ and measured from Earth to be 10 meters long fit into an Earth-based shuttle cargo bay 10 meters long?
Regarding the “muon argument” for length contraction, I said:I know that as particles travel faster their internal processes (muon decay here) slow down, so they “live longer.” So these muons travel further than expected. This does not mean that Earth’s atmosphere becomes thinner (contracted) to accommodate each incoming muon... “realistically speaking” that is... granting that Earth’s atmosphere stays about the same thickness/depth regardless of incoming muons.
Regarding the claims of time dilation for a spacecraft going to Alpha Centauri at near ‘c’ and length contraction of the distance from here to there, I said:"Earth orbits the sun 4.37 times (that's 4.37 years, as years are defined) during the time that light travels from Alpha Centauri to here. You are confused if you think that a spaceship can make the journey in less time. (Edit: Nothing with mass can travel as fast as light.) The ship's clock slows down relative to a given earth-based clock. So "ship's time" will go a lot slower for the ship than earth's time, but a year is standardized* based on one earth orbit. (*By very accurate clocks with less variation than successive orbits.)"For the ship" does not make the distance to AC less than 4.37 light years in the real universe as known to precise astronomy... nor does the ship's slower clock (time "for the passengers) make the journey possible "in ten minutes." This is science fiction dressed up as science... in "the emperor's new clothes."
So, there you have it... a summary of the issues debated in this thread and originally in my length contraction thread in the Physics section before it was banished as not scientific, not appropriate physics discussion.
It hasn't died, but you really need to stop slapping people across the face for attempting to answer your questions.
I'll label these with LU for Lorentzian Universe and SR for Einstein's Special Relativity.
SR: The muon finds a shorter physical path through the atmosphere which is not available to slower moving things. These shorter paths are always there, but only open to things that move fast....SR: As in the case of the muon, a shorter path (length) is available, as is a shortcut into the future.