between3and26characterslon Posted December 14, 2015 Share Posted December 14, 2015 How long does it take for an electron to jump an energy level? Does time exist in a singularity? isn't physics full of t=0? Have I not understood the question? Link to comment Share on other sites More sharing options...
swansont Posted December 14, 2015 Share Posted December 14, 2015 How long does it take for an electron to jump an energy level? Not zero. This articles has one measurement at 8 femtoseconds http://www.nytimes.com/2002/10/29/science/smile-electron-fast-camera-captures-action-around-atom.html Link to comment Share on other sites More sharing options...
imatfaal Posted December 14, 2015 Share Posted December 14, 2015 Just to nitpick a/o clarify and to check my understanding - whilst atomic clocks obviously do not function at absolute zero when the measurements are made at a fraction above abs zero the results are transformed to give the values as if at a limit of abs zero (the ground state). The famous number (which one of our moderators would love as a telephone number) 9 192 631 770 is the number of transitions at caesium's ground state at a temperature of 0 K. Link to comment Share on other sites More sharing options...
swansont Posted December 14, 2015 Share Posted December 14, 2015 Just to nitpick a/o clarify and to check my understanding - whilst atomic clocks obviously do not function at absolute zero when the measurements are made at a fraction above abs zero the results are transformed to give the values as if at a limit of abs zero (the ground state). The famous number (which one of our moderators would love as a telephone number) 9 192 631 770 is the number of transitions at caesium's ground state at a temperature of 0 K. Right. The people (at national standards labs) who determine the actual frequency have to estimate the effect that the non-zero temperature has on the atoms, both for the atoms themselves and the blackbody radiation from the surroundings. (As well as electric and magnetic fields, gravitational potential, and other effects) Link to comment Share on other sites More sharing options...
cjmg85 Posted January 15, 2016 Share Posted January 15, 2016 I think that the only time zero time would be possible is if there was 100% arrest of all motion universe wide, for if even one single thing was moving, it would be impossible to tell if it was that one thing moving, or everything else moving around it, and movement is time. Link to comment Share on other sites More sharing options...
ajb Posted January 15, 2016 Share Posted January 15, 2016 ... and movement is time. It is clear that we need a notion of time to define movement, i.e.,dynamics. However, it is not clear, nor generally taken to be true, that 'time is movement'. Link to comment Share on other sites More sharing options...
cjmg85 Posted January 15, 2016 Share Posted January 15, 2016 It is clear that we need a notion of time to define movement, i.e.,dynamics. However, it is not clear, nor generally taken to be true, that 'time is movement'. If nothing were moving anywhere in the entire universe, how would you know that any time has moved at all? I can't see that you would. When you start to move again you'll be picking up exactly where you left off. No time lost. Link to comment Share on other sites More sharing options...
swansont Posted January 15, 2016 Share Posted January 15, 2016 If nothing were moving anywhere in the entire universe, how would you know that any time has moved at all? I can't see that you would. When you start to move again you'll be picking up exactly where you left off. No time lost. Things still undergo decay. Is there evidence that this is tied to motion? Link to comment Share on other sites More sharing options...
studiot Posted January 15, 2016 Share Posted January 15, 2016 (edited) Actually you need time to pass for other processes than movement or motion, for example spontaneous radioactive decay. You could still measure time passage (or lack of it) by these means. Edited January 15, 2016 by studiot Link to comment Share on other sites More sharing options...
Commander Posted January 16, 2016 Share Posted January 16, 2016 Is there something like zero time. What does it mean. Prove it in nature . What would be the consequence of existence of this kind of time. For instance you can say hey zero time is at the verry begining of the universe. The moment of creation . The big bang . But it is not clear is there a creation at all and what if for instance the universe have existed forever. So in the second scenario there is no zero time. Prove it in nature . What sort of PROOF is TENABLE ? Link to comment Share on other sites More sharing options...
cjmg85 Posted January 16, 2016 Share Posted January 16, 2016 Things still undergo decay. Is there evidence that this is tied to motion? How can there be decay if there is no motion anywhere universe wide. No object anywhere, not even a single particle or molecule, would be in motion. Link to comment Share on other sites More sharing options...
ajb Posted January 16, 2016 Share Posted January 16, 2016 (edited) No object anywhere, not even a single particle or molecule, would be in motion. This is a very unphysical situation, so it is hard to make any meaningful comments. The question is what would happen to an unstable particle if it were isolated? That is if it were not causally connected to any other particles in the Universe. Would it still decay? Generally there seems to be some confusion about how we measure time, usually in terms of some periodic motion, and time itself, not that anyone can really say what time 'is'. Edited January 16, 2016 by ajb Link to comment Share on other sites More sharing options...
swansont Posted January 16, 2016 Share Posted January 16, 2016 How can there be decay if there is no motion anywhere universe wide. No object anywhere, not even a single particle or molecule, would be in motion. How can there not be decay if it doesn't depend on motion? Link to comment Share on other sites More sharing options...
cjmg85 Posted January 16, 2016 Share Posted January 16, 2016 This is a very unphysical situation, so it is hard to make any meaningful comments. The question is what would happen to an unstable particle if it were isolated? That is if it were not causally connected to any other particles in the Universe. Would it still decay? Generally there seems to be some confusion about how we measure time, usually in terms of some periodic motion, and time itself, not that anyone can really say what time 'is'. The question was can there ever be "zero time". My answer to that question was I believe that the only way there could ever be "zero time" is if there was 100% arrest of all motion universe wide. This would include arrest of motion for everything, completely frozen, nothing moving anywhere. Under that scenario, as unlikely as it is, there would be "zero time". It is my understanding of time that we do measure it, as you saw, on periodic motion. I'm not sure how time could ever be measured in any other way. Everything is always in motion whether you notice it or not, and it is all relative to the observer. On that note, here is a fun thought experiment I had a couple of weeks ago: Say a miner gets trapped in a mine shaft. He has absolutely no source of natural light down there (but he does have a flashlight the operates without batteries), and absolutely no communication at all to the outside world. He also isn't wearing a watch. The miner, assuming he can somehow keep himself alive down there, decides that he'll keep track of the amount of time he's been down there based off of his usual sleep cycle. He knows that he's usually tired and asleep by 9, and awake and ready for the day by 5. So, he waits it out til he falls asleep, and then when he wakes up again he makes a mark on the wall. He's been down there for what he perceives to have been one night. He does this over and over again, ticking off each new day as he wakes up. However the problem is, there is no way for him to know for sure if his system is accurate or not relative to time on the surface. He may think it is, but with no reference of time on the surface, his "days" could be off by a few days, a few weeks, a few years.... there is just no way for him to know for certain. Therefore, his only reference of time is sleeping and then waking again. For all he knows, he could have dozed off for ten minutes and awoke thinking it was all night. (I mean really, do YOU know how much time has passed for you between sleeping and waking without referencing something that will tell you). Link to comment Share on other sites More sharing options...
ajb Posted January 16, 2016 Share Posted January 16, 2016 The question was can there ever be "zero time". My answer to that question was I believe that the only way there could ever be "zero time" is if there was 100% arrest of all motion universe wide. This would include arrest of motion for everything, completely frozen, nothing moving anywhere. Under that scenario, as unlikely as it is, there would be "zero time". Or would that mean one could not measure time? For instance we have the heat death scenario where eventually the Universe will reach a state of thermodynamic equilibrium and nothing will change. Does this imply that time no longer exists? Say a miner gets trapped in a mine shaft... This sounds like question of the psychological perception of time. There have been experiments along the lines you suggest. Link to comment Share on other sites More sharing options...
cjmg85 Posted January 16, 2016 Share Posted January 16, 2016 How can there not be decay if it doesn't depend on motion? How can anything change state in a universe in which all motion is prohibited? Or would that mean one could not measure time? For instance we have the heat death scenario where eventually the Universe will reach a state of thermodynamic equilibrium and nothing will change. Does this imply that time no longer exists? This sounds like question of the psychological perception of time. There have been experiments along the lines you suggest. The point is that he would never know, because his only reference for time is his own sleep/wake cycle, just like our only reference of time on the surface is the apparent motion of the heavens above us. If we were to travel to another world in another solar system, our only reference of time there would be the same, only from that planet's frame of reference to the apparent motions of the heavens above it. It's all really just relative anyway, isn't it? Link to comment Share on other sites More sharing options...
ajb Posted January 16, 2016 Share Posted January 16, 2016 ...like our only reference of time on the surface is the apparent motion of the heavens above us. It is not our only reference of time. It is however the one we use to define a day or a year, depending on what apparent motion you referring to. If we were to travel to another world in another solar system, our only reference of time there would be the same, only from that planet's frame of reference to the apparent motions of the heavens above it. Okay, so naturally they would most likely use units of duration based on their day and year. I agree. It's all really just relative anyway, isn't it? Using different units of duration is not usually what we mean by 'relative'. Link to comment Share on other sites More sharing options...
cjmg85 Posted January 16, 2016 Share Posted January 16, 2016 It is not our only reference of time. It is however the one we use to define a day or a year, depending on what apparent motion you referring to. Okay, so naturally they would most likely use units of duration based on their day and year. I agree. Using different units of duration is not usually what we mean by 'relative'. Well, whether that's what's "really meant" by it or not, did it not get the point I was trying to make across? And if the planet was moving at a different velocity than Earth, wouldn't the difference of velocity bring some sort of time dilation into effect (no matter by how big or how small). I'm still relatively new to a lot of this btw, so you will have to pardon any ignorance on my part. I am here to discuss and debate things, thus, I am here to learn more. Link to comment Share on other sites More sharing options...
ajb Posted January 16, 2016 Share Posted January 16, 2016 Well, whether that's what's "really meant" by it or not, did it not get the point I was trying to make across? And if the planet was moving at a different velocity than Earth, wouldn't the difference of velocity bring some sort of time dilation into effect (no matter by how big or how small). When transforming measurements between different frames one will encounter time dilation. So, yes there will be such effects. But this is not really related to the fact that we have different lengths of days on different planet. Link to comment Share on other sites More sharing options...
swansont Posted January 16, 2016 Share Posted January 16, 2016 How can anything change state in a universe in which all motion is prohibited? Motion is relative. A particle still decays in its own frame, in which it is motionless. If you require all motion cease, then you are positing a physically impossible case, much like positing perpetual motion. Can't really draw a valid conclusion if you toss the rulebook. Link to comment Share on other sites More sharing options...
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