Register to reply 
The problem of timeby mangaroosh
Tags: time 
Share this thread: 
#1
Feb1312, 01:49 AM

P: 359

I've been discussing Lorentzian and Einsteinian relativity here on PF, as well learning about them elsewhere, and a question occurred to me, and I thought that this might be the place to post it.
The problem of time, as I understand it, is based on the fact that quantum mechanics and Einsteinian relativity use different concepts of time; I've read that QM uses "a more Newtonian" concept. I'm just wondering if this issue would be the same under Lorentzian relativity, which also seems to incorporate a more Newtonian concept of time? Given that both Lorentzian and Einsteinian relativity are not distinguished by means of experimental evidence, would it be possible to unify QM with Lorentzian relativity; are there any such attempts? EDIT: I was going to add a point on the WheelerDeWitt equation, but I didn't think it was relevant, but if my understanding, that the mathematics of Einsteinian and Lorentzian relativity are the same, then perhaps it might be relevant. My basic understanding if the WheelerDeWitt equation is that time does not appear in it, suggesting that the universe is timeless; while Lorentzian relativity includes the notion of absolute time, it is a short distance from the notion of absolute time to timelessness. 


#2
Feb1312, 12:06 PM

P: 1,097

I like talking about time,
I can't make a question out of "The problem of time, as I understand it, is based on the fact that quantum mechanics and Einsteinian relativity use different concepts of time; I've read that QM uses "a more Newtonian" concept. I'm just wondering if this issue would be the same under Lorentzian relativity, which also seems to incorporate a more Newtonian concept of time?" So what's up for discussion? 


#3
Feb1312, 12:51 PM

P: 5,625

Einstein defined time as the movement of a clock hand. In other words, the best he could come up with is that 'time is the measurement of time'. It struck me as completely unsatisfactory, and yet I've never heard any better. Hardest concept ever to define.



#4
Feb1312, 04:54 PM

Mentor
P: 22,243

The problem of time
Why is 'time is what clocks measure' any less satisfactory than 'length is what rulers measure'?



#5
Feb1312, 05:00 PM

Sci Advisor
PF Gold
P: 3,518

what became of those Cern neutrinos that stepped to a different drummer ? 


#6
Feb1312, 05:02 PM

P: 3,015




#7
Feb1312, 06:28 PM

P: 1,097

(of course ignoring the "human" aspect of the question) 


#8
Feb1312, 06:37 PM

HW Helper
PF Gold
P: 1,924

Hello mangaroosh,
Don't be confused, but QM works, and works quite well, when combined with Einstein's special relativity. And any Lorentzian form of physics is trumped by special relativity; so there's no point in going backwards. Summary: relativistic QM and Einstein's special relativity use the same concepts of time (and spacetime, for that matter). Points of interest:
It's QM and Einstein's general relativity that don't fit together well. QM, even relativistic QM, assume a flat spacetime (special relativity assumes a flat spacetime too), but with GR spacetime can be, and generally is, curved. But spacetime (and time) in GR is really moreorless the same interpretation of spacetime (and time) in special relativity; it's just that spacetime in GR is curved is all. 


#9
Feb1312, 09:00 PM

P: 359

Up for discussion is anything to do with the nature of time really, but the question in the above is whether or not it would be possible to unify Lorentzian relativity with QM and to resolve the "problem of time"? 


#10
Feb1312, 09:16 PM

P: 359

The question I would ask is, how exactly does a clock measure time; that is, how is the physical property of time measured by a clock? If we take an atomic clock for example, it is the number of oscillations of a caesium atom which are measured (or counted), not some secondary physical property called "time". 


#11
Feb1312, 09:25 PM

P: 359

are you familiar with the term "the problem of time"; just wondering what your interpretation of it is? 


#12
Feb1412, 06:18 PM

HW Helper
PF Gold
P: 1,924

I guess my original point though was that above Planck scales, QM and special relativity are already together, so there's no point in taking a step backwards into Lorentzian aether. That was really my only point. 


#13
Feb1412, 08:08 PM

P: 359

Unfortunately, I don't fully understand the issue, but my understanding is that standard quantum theory doesn't incorporate the notion of gravity, while it is a central part of GR, to the extent that both are incompatible as they are i.e. quantum theory would require some formulation of gravity in order to be unified with GR  I'm not sure what would need to be changed in GR to marry it with quantum theory. I was more just wondering if the aforementioned "problem of time" could be resolved through Lorentzian relativity, because it also uses the concept of absolute time. From discussing it with some people on here, and according to the wiki entry (I haven't searched further yet) it appears that "neoLorentzian relativity" has effectively been stripped of everything but the concept of an undetectable, absolute rest frame  that includes the aether I think. Again, from discussing it with people, the postulation of this absolute rest frame appears to be one of the main reasons (the only one I have heard raised actually) as to why Einsteinian relativity is preferred over Lorentzian. I'm wondering, if the absolute rest frame were done away with, would it put Lorentzian relativity on par with Einsteinian, given that experiments do not distinguish between either? 


#14
Feb1512, 07:42 AM

P: 5,625




#15
Feb1512, 10:21 AM

P: 98




#16
Feb1512, 11:13 AM

P: 5,625




#17
Feb1512, 02:40 PM

Mentor
P: 22,243




#18
Feb1512, 03:16 PM

P: 5,625

Time doesn't have a group of things in the same class that help define it. 


Register to reply 
Related Discussions  
Problem of time: Notime theories?  Beyond the Standard Model  14  
Time Dilation Problem; Find the proper time, ts.  Introductory Physics Homework  4  
Problem: Orbital Period  eclipse time  Illumination time ?  Introductory Physics Homework  1  
Why is physical timeasymmetry vs dynamical law timesymmetry a problem?  General Physics  8 