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(Score: 1, Insightful) by Anonymous Coward on Friday February 28, @09:56PM
(13 children)
by Anonymous Coward
on Friday February 28, @09:56PM (#1394755)
It's having to stay dead all that time that scares the hell out of me.
Time doesn't exist for the dead. An infinite amount of time goes infinitely fast. You sleep, and instantly wake up in a different universe. How long you were out, you will ever know. What scares me is that the cycle repeats indefinitely. Maybe the purpose of religion is to break the cycle by biulding a "consciousness" without the flesh
Unless I am misunderestimating something (to borrow a G W Bush'ism), a photon could travel 13.7 billion light years from the edge of the universe to our position and when it arrives, from the photon's point of view, zero time has passed since it is moving at speed C.
-- The Centauri traded Earth jump gate technology in exchange for our superior hair mousse formulas.
If you look at the half-life of a stationary muon, it is very short. If you look at the half-life of cosmic-ray muons that are moving at an appreciable fraction of the speed of light, they are seen/measured/calculated as much longer*. That's relativistic time dilation. BUT the muon experiences the half-life as being the same duration in both scenarios.
Note that external observers always see photons as travelling at the speed of light relative to themselves, no matter what sub-lightspeed velocity they themself have. Photons will be red- or blue- shifted according to the velocity of the observer. Anything with rest-mass cannot accelerate to light-speed as that would require infinite energy.
So yes, asking about a photon's point of view with respect to time is a bit like asking "What colour is an idea?": the question can be posed, but is difficult, if not impossible to answer.
It's is aimed at the interested (and committed) layman - to quote from the preface:
It is a straightforward, honest explanation of a rather difficult subject-the theory of quantum electrodynamics-for a nontechnical audience. It is designed to give the interested reader an appreciation for the kind of thinking that physicists have resorted to in order to explain how Nature behaves. If you are planning to study physics (or are already doing so), there is nothing in this book that has to be "unlearned": it is a complete description, accurate in every detail, of a framework onto which more advanced concepts can be attached without modification. For those of you who have already studied physics, it is a revelation of what you were really doing when you were making all those complicated calculations!
*It's interesting how this is done. https://en.wikipedia.org/wiki/Muon#Muon_sources [wikipedia.org] - it is either time dilation from the point-of-view/frame-of-reference of the observer, or length contraction according to the point-of-view/frame-of-reference of the muon. The descriptions/explanations are mutually exclusive/complementary, but equally valid.
(Score: 0) by Anonymous Coward on Tuesday March 11, @09:27AM
by Anonymous Coward
on Tuesday March 11, @09:27AM (#1395982)
Anything with rest-mass cannot accelerate to light-speed as that would require infinite energy.
To paraphrase Leonard Susskind; "Photons have no mass because they are massless particles". Joking aside, a Photon would have an estimated rest-mass on the order one quintillionth that of a Neutrino. We cannot hope to measure it so we correctly say "practically massless", the implication being that the momentum of Photons or hypothetical Gravity messenger particle could be slightly slower than the ultimate quantum speed of causality.
That's a good summary of what I believe, or at least want to believe. As I've said before, the problematic bit is if a universe can get stuck in an eternally lifeless state a.k.a. Heat Death. I have a hunch it can't but no hard evidence. But then, you did say an infinite amount of time goes infinitely fast, so are we to imagine reaching an end to an eternal Heat Death after instantly traversing an entire eternity? That's a wacky idea but if Achilles can catch the tortoise I suppose it might be conceivable. Any mathematicians care to weigh in?
-- Welcome to Edgeways. Words should apply in advance as spaces are highly limite—
I guess it comes down to a question of how stable is reality? Will the laws of physics change if you wait enough eons? It likely depends on what layers of complexity exist outside of observable physics. If the universe was just a game running on some kid's computer, eventually it will be switched off or crash.
-- Welcome to Edgeways. Words should apply in advance as spaces are highly limite—
(Score: 1, Insightful) by Anonymous Coward on Friday February 28, @09:56PM (13 children)
Time doesn't exist for the dead. An infinite amount of time goes infinitely fast. You sleep, and instantly wake up in a different universe. How long you were out, you will ever know. What scares me is that the cycle repeats indefinitely. Maybe the purpose of religion is to break the cycle by biulding a "consciousness" without the flesh
"We never really die" - Lucy
(Score: 3, Interesting) by hendrikboom on Saturday March 01, @02:53AM (4 children)
Are photons dead?
(Score: 4, Funny) by Anonymous Coward on Monday March 03, @12:02AM
Would we call the ceremony a requiem or a rest mass?
(Score: 2) by DannyB on Monday March 03, @03:22PM (2 children)
Life on a photon would be timeless.
Unless I am misunderestimating something (to borrow a G W Bush'ism), a photon could travel 13.7 billion light years from the edge of the universe to our position and when it arrives, from the photon's point of view, zero time has passed since it is moving at speed C.
The Centauri traded Earth jump gate technology in exchange for our superior hair mousse formulas.
(Score: 1) by pTamok on Wednesday March 05, @09:01AM (1 child)
...to an external observer.
If you look at the half-life of a stationary muon, it is very short.
If you look at the half-life of cosmic-ray muons that are moving at an appreciable fraction of the speed of light, they are seen/measured/calculated as much longer*. That's relativistic time dilation. BUT the muon experiences the half-life as being the same duration in both scenarios.
Asking what the frame of reference of a photon is cannot be answered (easily) in relativity because it requires doing things like dividing by zero or adding infinite quantities to things.
Discussion here:
https://physics.stackexchange.com/questions/54162/how-does-a-photon-experience-space-and-time [stackexchange.com]
and here (note 'affine parameter' and 'limit of proper time'):
https://physics.stackexchange.com/questions/27794/is-a-photon-fixed-in-spacetime [stackexchange.com]
Note that external observers always see photons as travelling at the speed of light relative to themselves, no matter what sub-lightspeed velocity they themself have. Photons will be red- or blue- shifted according to the velocity of the observer. Anything with rest-mass cannot accelerate to light-speed as that would require infinite energy.
So yes, asking about a photon's point of view with respect to time is a bit like asking "What colour is an idea?": the question can be posed, but is difficult, if not impossible to answer.
If you want to know more about the behaviour of photons, try reading Richard Feynman's book "QED: the strange theory of light and matter", which is available from the Internet archive, here: https://archive.org/download/richard-feynman-pdf-library/Feynman%2C%20Richard%20%2837%20books%29/QED/Feynman%2C%20Richard%20-%20QED%20%28Princeton%2C%202006%29.pdf [archive.org]
It's is aimed at the interested (and committed) layman - to quote from the preface:
*It's interesting how this is done. https://en.wikipedia.org/wiki/Muon#Muon_sources [wikipedia.org] - it is either time dilation from the point-of-view/frame-of-reference of the observer, or length contraction according to the point-of-view/frame-of-reference of the muon. The descriptions/explanations are mutually exclusive/complementary, but equally valid.
(Score: 0) by Anonymous Coward on Tuesday March 11, @09:27AM
To paraphrase Leonard Susskind; "Photons have no mass because they are massless particles". Joking aside, a Photon would have an estimated rest-mass on the order one quintillionth that of a Neutrino. We cannot hope to measure it so we correctly say "practically massless", the implication being that the momentum of Photons or hypothetical Gravity messenger particle could be slightly slower than the ultimate quantum speed of causality.
Which is to say; we're all with Lenny on this!
(Score: 2) by acid andy on Saturday March 01, @10:44AM (7 children)
That's a good summary of what I believe, or at least want to believe. As I've said before, the problematic bit is if a universe can get stuck in an eternally lifeless state a.k.a. Heat Death. I have a hunch it can't but no hard evidence. But then, you did say an infinite amount of time goes infinitely fast, so are we to imagine reaching an end to an eternal Heat Death after instantly traversing an entire eternity? That's a wacky idea but if Achilles can catch the tortoise I suppose it might be conceivable. Any mathematicians care to weigh in?
Welcome to Edgeways. Words should apply in advance as spaces are highly limite—
(Score: 0) by Anonymous Coward on Saturday March 01, @08:37PM (6 children)
We could be dead for an infinite number of eternities, it's still instantaneous. The chronometer is inoperative. You'll never know it happened
(Score: 2) by acid andy on Saturday March 01, @09:29PM (5 children)
I guess it comes down to a question of how stable is reality? Will the laws of physics change if you wait enough eons? It likely depends on what layers of complexity exist outside of observable physics. If the universe was just a game running on some kid's computer, eventually it will be switched off or crash.
Welcome to Edgeways. Words should apply in advance as spaces are highly limite—
(Score: 3, Interesting) by The Vocal Minority on Sunday March 02, @06:18AM (3 children)
"That which dead may not eternal lie
For in strange eons death may die"
:)
(Score: 2) by turgid on Sunday March 02, @11:30AM (2 children)
The Thing That Should Not Be?
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].
(Score: 3, Informative) by The Vocal Minority on Monday March 03, @07:03AM (1 child)
Well...yes, but Metallica were quoting from HP Lovecraft's "The Call of Cthulhu" (or one of his stories anyway).
(Score: 0) by Anonymous Coward on Thursday March 13, @05:46PM
Wish I'd known earlier that Lovecraft was a massive bigot.
(Score: 0) by Anonymous Coward on Sunday March 02, @11:20PM
:-) Have no fear.. This one will last as long as you do