Real-Time Physics

Thomas Ray

Don Koks' nice explanation of clocks in special relativity by way of John Baez.

John Merryman

Tom,

"Dude, that is Einstein starting to explain *why* clocks don't measure anything."

There is this academic discipline, called 'Physics' and there is this pervasive effect throughout nature, manifesting as the coming and goings of all form, called time. My interest isn't in mind games by people who manifestly cannot explain this effect, but in what is the basis and consequences of that effect, since I have to live it. I suppose thermometers can't read anything either, but when my alarm clock goes off in the morning, I'd better get out of bed and when the thermometer outside my door reads 32f, I dress warmly. Maybe it is just personal experience, but that is what I'm trying to make sense of, not some else's convoluted multiworlds/blocktime chalkboard meanderings.

"No, John. There is no "larger reality"

You better tell that to the people running the GPS system! Apparently they have been misinformed about how to go about mapping the surface of the planet.

"What distance equals "6 degrees"?"

That obviously depends on the size of the clock!!!!

"What direction is "somewhere else"?"

Obviously somewhere physically removed from where it started!!! Is the term 'vector' completely meaningless, if it isn't immediately connected to some actual geographic plotline????

" The integral governing the principle of least action (more accurately, stationary action) has no magnitude."

So zero is not part of any scale? Gosh! Learn something new every day.

Regards,

John M

John Merryman

Tom,

""The clock isn't measuring *anything*!! The clock is the aggregate of regular repeating physical processes.""

So doesn't this mean that time is just an effect of those "repeating physical processes?" In other words, the process forms one wave, then dissolves it, as it is forming the next wave?

Such that waves prior to and succeeding the current configuration do not physically exist?

Regards,

John M

John Merryman

And thus your perception of any particular wave is simply a function of how far it has to travel to your point of view, relative to others. Such that light from a distant star will take longer to reach one observer than someone closer, so they perceive events before you. Thus time and its many disparities of perception has to do with actual physical relationships, not some 'fabric of spacetime?'

Thomas Ray

"My interest isn't in mind games by people who manifestly cannot explain this effect, but in what is the basis and consequences of that effect, since I have to live it."

Well live it in good health and enjoyment. Do you enjoy getting a cold reception from those whose life is invested in the mind games of physics -- when you claim that "your life" is some non-mind-game you call "physics," and you think everyone else should call it physics, too?

Really, John?

Best,

Tom

Thomas Ray

"So doesn't this mean that time is just an effect of those 'repeating physical processes?'"

No. It doesn't.

"In other words, the process forms one wave, then dissolves it, as it is forming the next wave?"

No. There are reinforcing waves, as well as destructive and interfering ones.

"Such that waves prior to and succeeding the current configuration do not physically exist?"

Explain what you mean by 'physically exist.'

Thomas Ray

"And thus your perception of any particular wave is simply a function of how far it has to travel to your point of view, relative to others."

A wave is not a function of distance or time. If you had the consciousness of a wave particle packet -- a photon -- you would have no idea of space or time.

"Such that light from a distant star will take longer to reach one observer than someone closer, so they perceive events before you."

No. What do you mean by "before?"

"Thus time and its many disparities of perception has to do with actual physical relationships, not some 'fabric of spacetime?'"

It's the fabric of spacetime that is physically real -- not your personal perception of the physical relationships, that you determine by fiat.

John Merryman

Tom,

I don't determine it by fiat. All we have are theories and observations. Now we are quite capable of theorizing lots of things, from supreme beings to time traveling wormholes. All I, or anyone else has in the way of observations about time is changing configurations and specific measurements of change. What we find are there are apparently no universal measurements of this process of change. Each action is its own rate.

Now contrary to your insistence on the success of the physics community in explaining time, there does exist quite a variety of views on the subject. From the currently fairly mainstream assertion that it is illusion, to Lee Smolin arguing the only reality is time. NewSceintist recently ran a cover story, Saving time: Physics killed it. Do we need it back? on the subject. In fact, FQXI's first contest asked; What is the Nature of Time. I guess they should have just handed the mike over to you.

Regards,

John M

Eckard Blumschein

Tom,

You are trying in vain to evade a simple but compelling argument: Nobody can seriously deny that in reality past and future are different while this is ignored in tense-less physics because the common notion of time has no natural zero. Instead, AD 2013 (anno domini = year of the Lord) means the number of years elapsed after Christ's birth. You are trained to count these years from this arbitrarily chosen moment on an event-related scale up to the current border between the past and future, i.e. to the now. Alternatively we can count "backward" (if seen in the commonly agreed perspective) from now to Christ's birth 2013 years ago. Next year the chosen t=0 will have been shifted to 2014 years ago. Do you have any problem with that?

Both views have their merits. The view from now "backward" to any past event has a natural zero, the now, and it does always exactly separate the past from the future. This scale is not located on a line but on a one-sided ray that has permanently its origin at the current now and points to events in the past.

In order to avoid confusion, I suggest referring to the two-sided scale with the necessarily arbitrarily chosen zero as the time scale or with more emphasis the scale of common time while the one-sided scale is the scale of currently elapsed time.

So easy is the solution to a problem that worried Einstein seriously - so easy except for some consequences to theories that were taboo for Einstein and Hilbert and are unfortunately still sacrosanct for every mediocre mathematical physicist who naively believes that nature is a just a model of itself.

Eckard

Thomas Ray

"You are trying in vain to evade a simple but compelling argument ..."

Compelling to you, Eckard. Simple to me.

[deleted]

"From the currently fairly mainstream assertion that it is illusion, to Lee Smolin arguing the only reality is time."

John, you always talk about Lee Smolin -- and Julian Barbour, too -- as if you understand them. To know what they are saying, though, you would have to understand relativity.

John Merryman

Tom,

As math, or as physics? In case you haven't noticed, I just don't think the 'fabric of spacetime' is physically real. No more than those giant cosmic gear wheels explained why epicycles were so mathematically predictive. Be careful when you assign agency to pattern.

I don't buy Smolin's or Barbour's interpretations either, I'm just using them as examples of these issues not being as settled as you present.

Regards,

John M

pjackson

Eckard,

May I suggest that considering 'rate' of time overcomes Tom's argument. It is after all only 'rate of ticking' and it's relation to motion that time and relativity is fundamentally about.

QM's 'absolute' rate of time is entirely compatible with SR's if we consider the postulates alone, as the 'rate of time' is the same for identical clocks in all inertial systems.

Now just properly define inertial systems as 'locally real' (i.e. made of matter with spatial limits, not some imaginary 'wonderland') and all the confusion evaporates. Light signals are just signals which change speed with all other signals to maintain propagation speed c locally, giving the Doppler shift.

In the constant c = f*lamba, c and lambda are changed inversely when propagation frame changes to conserve c locally giving c' - f*lambda'.

How would the EM signals representing clock emissions be somehow immune to normal Doppler shifts?

Peter

Thomas Ray

John,

Thanks for linking the New Scientist article. I am a subscriber, and haven't made time lately for reading it. It's a pretty good survey article.

I like Ellis' evolving blocktime model except for the wrong turn he made, in accepting the Copenhagen interpretation of quantum mechanics; i.e., that the wave function collapse is real, therefore reality is probabilistic and observer created. (George, please return to your strong roots as a relativist.) He would make more progress in my opinion, if he followed Sean Carroll's advice:

"Carroll prefers the 'many worlds' scenario, in which every quantum possibility occurs in different universes: the present Schrödinger's cat is dead in some universes, but alive in others."

Best,

Tom

Thomas Ray

"As math, or as physics?"

Do you think you understand it (relativity), either way?

John Merryman

Tom,

Conceptually its not that deep, but doing the actual calculations is very complex.

I think the problem is this concept of spacetime will prove to be diversionary and that it is the overlooked aspects of space which dictate how mass/energy moves around in it. Treating space as simply a three dimensional grid is simplistic. Quantum theory has a better view of space, at least in that the instability is microcosmic, ie. fluctuations, not macrocosmic ie. the whole universe expanding as one. The convection cycle of expanding radiation and collapsing mass, builds up from that base instability. A top down concept of the entire universe expanding and possibly contracting as one, only ties together some divergent observations and needs all those invisible elements to make it work. Time is simply an effect of the resulting changing configurations.

Regards,

John M

Thomas Ray

"Conceptually its not that deep, but doing the actual calculations is very complex."

Actually, it's just the opposite.

"I think the problem is this concept of spacetime will prove to be diversionary and that it is the overlooked aspects of space which dictate how mass/energy moves around in it."

That would be some trick, since the framework is free of background coordinates.

"Treating space as simply a three dimensional grid is simplistic."

Only if you think that is what relativity does.

"Quantum theory has a better view of space, at least in that the instability is microcosmic, ie. fluctuations, not macrocosmic ie. the whole universe expanding as one."

You think we live in two different spaces?

"The convection cycle of expanding radiation and collapsing mass, builds up from that base instability."

What base instability?

"A top down concept of the entire universe expanding and possibly contracting as one, only ties together some divergent observations and needs all those invisible elements to make it work. Time is simply an effect of the resulting changing configurations."

John, you really have no idea of how relativity treats spacetime.

John Merryman

Tom,

As I keep arguing against the many words model, is that it inserts time as that line from past to future and so you have the features of a determined past being applied to a probabilistic future, rather than simply letting the actions run in their own time free dynamic and the effect of time emerging from the results. Those quantum particles don't have any past of future, they only have momentum. Just totally get rid of any concept of time when thinking about that level. Its only when you step back and think about where they were and where they might go next, that you have time. There is only that quantum presence, not present. It doesn't collapse, because space doesn't collapse, so one configuration of that quantum presence leads to another.

Regards,

John M

John Merryman

Tom,

I treat space and basis and time as effect.

The reason I don't like Ellis' view of the evolving blocktime, is that energy is conserved and events are very much a function of perceptions, so that since the actual physical past no longer exists, since its material reality is constantly shifting into new configurations, the past is being lost and any effort to measure or otherwise consider it, only results in further changes, ie. uncertainty principle. You might say the present is being woven from strands pulled out of what was previously woven and time is lots of such cycles of information, in a constantly evolving tapestry.

Sorry to make this as assertions and not directly address your skepticism, but having to rush.

Regards,

JohnM

John Merryman

Sorry also for the various typos;

Many worlds, not words

quantum particles don't have any past or future

space as basis

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