Time - does it exist?

Time is continuous?

I think an increasing large body of theoretical physicists would disagree.

Quantization of space and time have been the focus of research for the last 50 years.

One also needs to distinguish between the concepts of "time" the emergent property, and "time" a fundamental building block.

The previous examples demonstrate the former, NOT the latter.

Cheers

Richard

quote:

Originally posted by paremus:
I think an increasing large body of theoretical physicists would disagree.
Richard

just curious, do we have any physicists on this forum (an undergrad degree would do)?

from a rudimentary mathematical perspective time appears to be continuous. if you take a second and divide it by 2 ad infinitum, you will approach zero but never reach it. in a freshman level class in discreet mathematics that would be sufficient to establish that time is continuous and not discreet.

but the real world is a tougher place to make that case.

here's an interesting hypothetical experiment.
if there was a movie camera in which the frame rate could be increased to infinity, would you find a frame rate at which some of the frames would be blank? the blank frames would prove time to be discreet and not continuous.

quote:

if there was a movie camera in which the frame rate could be increased to infinity, would you find a frame rate at which some of the frames would be blank? the blank frames would prove time to be discreet and not continuous.

Ans = Yes (wrt to 2some of the frames would be blank")

Cheers

Don

quote:

Originally posted by Don Atkinson:

quote:

if there was a movie camera in which the frame rate could be increased to infinity, would you find a frame rate at which some of the frames would be blank? the blank frames would prove time to be discreet and not continuous.

Ans = Yes

Cheers

Don

who conducted what experiment that provided
ans = yes?

quote:

who conducted what experiment that provided

you said it was hypothetical.......

but fyi, the blank frames would be those that were exposed during the gaps in the stream of photons.

cheers

Don

Don, Mike - I think paremus hit the nail on the head:

quote:

Quantization of space and time have been the focus of research for the last 50 years.

This is especially true in the field of Quantum Gravity (the attempt to unify Quantum Mechanics and General Relativity). Nothing proven, though. In fact, I'm not sure the theories are well developed enough to produce practical experimental tests yet.

We do have a physicist here - he's been on telly and everything. It's the guy that used to be in D:ream ("Things can only get Better") but I can't remember his forum name.

Undergraduate in Physics.
Phd in AstroPhysics

Cheers

Richard

re Continuous time.

Heisenberg's uncertainty principle sort of screws the divide by 2 argument.

The same argument was used by the greeks to prove logical inconsistencies with the idea of continuous space.

Regards

Richard

Drodzilla

You are right. Many theories, a few fanatical / religious standpoints but nothing proven yet. The major camps are the String theorists v.s. Loop Gravity. For those interested in some of the current issues & arguments - I'd recommend reading "Not Even Wrong" - by Peter Woit.

Failing that - watch 'Big Bang' sitcom

Cheers

Richard

quote:

Originally posted by paremus:
For those interested in some of the current issues & arguments - I'd recommend reading "Not Even Wrong" - by Peter Woit.
Richard

thanks paremus, i just ordered "not even wrong".
will the limited math and physics of an undergrad in computer science be adequate to "get" this book. or will i be doing the "monkey meets Shakespeare" dance?

BTW, i watch "big bang theory" every week. amusing :-)

quote:

(the attempt to unify Quantum Mechanics and General Relativity). Nothing proven, though.

Could be that neither is a good enough approximation to reality at either the macro scale of general relativity or the micro scale of quantum mechanics.

And it might be that a "discontinuity" exists in reality.

Cheers

Don

Mike -

The maths isn't heavy - you should be fine. Woit argues against the current String dogma. Beware - once you start down this path - there is no going back

A good follow-on - arguing from a similar view point - is 'The Trouble with Physics' Lee Smolin. Again - no heavy maths.

Don's question regarding discontinuity and reality.

There is certainly a discontinuity between General Relativity and QM theories - however these are only mathematical constructs.

However high energy particles - i.e. cosmic rays - are influenced by Relativity (time dilation) whilst also being quantum mechanical. So it would seem unlikely that Reality has such a discontinuity. Rather GR and QM are each approximations to an underlying theory.

The real problem at present is lack of experimental techniques to pin done the candidate theories and rigorously test them. I suspect its unlikely that the Hadron collider will help here - BUT - I really hope I'm wrong

Cheers

Richard

quote:

Originally posted by paremus:
Mike -

The maths isn't heavy - you should be fine.

The real problem at present is lack of experimental techniques to pin done the candidate theories and rigorously test them. I suspect its unlikely that the Hadron collider will help here - BUT - I really hope I'm wrong

Cheers

Richard

thanks, i'm excited. something new from the forum. i'll let you know how it goes :-)

the real problem : idea + $$$ with the global slowdown in economies ...

quote:

The maths isn't heavy - you should be fine. Woit argues against the current String dogma. Beware - once you start down this path - there is no going back

A good follow-on - arguing from a similar view point - is 'The Trouble with Physics' Lee Smolin. Again - no heavy maths.

Mike - for what it's worth, I've read both, and much prefer Smolin to Woit - it's better written and addresses the philosophical issues much better (IMHO of course). I think Smolin's a great popular science writer - his "Three Roads to Quantum Gravity" is also excellent (you feel that you *almost* understand what he's writing about!).

Regards
Nigel

Nigel

Are these books more or less free from author bias ie do the authors make it clear where there is peer consent based on verified experimental results and where opinion/theory is divided.

cheers

Don

Here is an interesting thought. If for a given period I were to reverse the movement of all atoms in the universe, would time be going backwards or still forwards?

Andrew

quote:

Originally posted by Andrew Randle:
Here is an interesting thought. If for a given period I were to reverse the movement of all atoms in the universe, would time be going backwards or still forwards?

Andrew

you can do that! WOW!

Conversely, if time moved backwards for a moment, would all atoms (and sub-atomic particles/waves/gravitational forces etc etc) retrace their spacial directions?

Does time (if it has any fundamental meaning) progress at the same rate and in the same sense, throughout the universe?

Are the properties of the universe constant from place to place and from time to time and has this been the case since the "Big Bang"

Cheers

Don

To find out whether time exists, simply try being late [a few minutes each time should suffice] for work three days running, and then study resultant shortage in the wage slip for a practical demonstration that time does really exist in daily life.

On the other hand if you want brain ache we can always speculate about what might happen when Andrew Randle manages to get all the atoms [in the universe?] to reverse there direction!

It is a matter which is a fun diversion if you have that turn of mind, but only being a simpleton mself, I tend to think it is incomprehansible beyond a rather superficial level!

Keep it up: It is like the old Radio Three Science programmes, where they lost me in the first thrity seconds, but I liked the melifluous sounds of the voices, while paying next to no attention to the actual meaning of the wisdom being offered!

ATB from George

Bring back Magnus Pike and James Burke - there's no more heroes any more.

quote:

Originally posted by GFFJ:
Keep it up: It is like the old Radio Three Science programmes,

ATB from George

or Mystery Science Theater ---

I would also speculate that most of us have the experience of time not actually seeming to be measured in a constant unit!

It is amazing how long the last twenty minutes on a Friday afternoon [or whenever your work finsihes for the week] can seem, especially if you have wound up everything there is to do, whereas twenty minutes of music can seem to pass in only a few seconds!

So is the second an accurate reflection of the time time it takes to pass a second in every case? Empirical evidence might suggest not.

Does time continue if you are not there to notice its passing? Even if yes, then why does the night seem so short when there is work to do next day, and so long if there is nothing essential to do next day?

Being less whimsical for a second, is there any evidence at all that time is not assessed with such accuracy that we as humans can detect a difference? There was some experiment with atomic clocks placed at the Equator and at the [North?] Pole and there seemed to be some inexactitude. Possibly I have got this entirely wrong ...

On the other hand Walcha's recording of the Bach Goldbergs always seems to take 75 minutes on the clock to play, and only half that length of time to listen to ...

Does anyone recall those fearful school speech day rambles from the Head, which certainly took longer to listen to than they racked up on the clock ...

Dobranoc, George

quote:

There was some experiment with atomic clocks placed at the Equator and at the [North?] Pole and there seemed to be some inexactitude. Possibly I have got this entirely wrong ...

There is certainly a measurable difference between the passage of time in the atomic clocks in the Navstar (GPS)satellites compared to the atomic clocks in the Navstar earth-based Master Stations.

Cheers

Don

according to Eric Woolfson

Time, flowing like a river
Time, beckoning me
Who knows if we shall ever meet again
If ever
But time
Keeps flowing like a river
To the sea