The present time

[Greg Boyles]

But I would like to add... Whilst the past is not happening right now, the past does have a now that is happening.

 

 

 

Without two bits of matter, you have no acting clocks. In a universe devoid of matter, where are your clocks so you can make measurements?

 

It's all about relativity.

 

We hve currently have no way of detecting and measuring the Higg's Boson particle. But does that amount to absolute certainty that it does not exist?

 

Same principle if the universe was totally devoid of matter and energy.

 

What about space itself - it is supposed to not be empty. Perhaps it you looked close enough at the fabric of space you could discern events moving across the ruler of time even if there is no matter an energy.

[Mystery111]

I actually promised someone I would make a thread on time. If I find time the next couple of days, I will.

 

We hve currently have no way of detecting and measuring the Higg's Boson particle. But does that amount to absolute certainty that it does not exist?

 

Same principle if the universe was totally devoid of matter and energy.

 

What about space itself - it is supposed to not be empty. Perhaps it you looked close enough at the fabric of space you could discern events moving across the ruler of time even if there is no matter an energy.

 

Pfft... of course we have ways to view the Higgs. If it was there, it would have been found by the LHC.

 

And no that isn't the same principle I am afraid.

 

As for space, you are right - no small square measurement of space is devoid of matter... every tiny part of space is filled with vacuum energy. But I am sorry, you will need to rephrase the last bit, had trouble understanding it.

[MigL]

Really ???

 

"In a universe devoid of matter, where are your clocks so you can make measurements?"

 

Let's take it one step farther. In a universe devoid of matter, where are your yardsticks so you can measure the 3 spatial dimensions ? Or are you saying they are fictitious too ?

If you have no standard to measure them against, a meter might as well be 1000000 meters.

 

Time is not like the other dimensions through which we are free to move, rather we are carried along with time as it moves.

[Mystery111]

Really ???

 

"In a universe devoid of matter, where are your clocks so you can make measurements?"

 

Let's take it one step farther. In a universe devoid of matter, where are your yardsticks so you can measure the 3 spatial dimensions ? Or are you saying they are fictitious too ?

If you have no standard to measure them against, a meter might as well be 1000000 meters.

 

Time is not like the other dimensions through which we are free to move, rather we are carried along with time as it moves.

 

I laughed when I read this... you were making a mockery of what was being suggested, but you actually hit jackpot!

 

Three dimensions of space involve low energy physics and the emergence of this physics is called geometrogensis. There has been some revolutionary work on this, suggesting that the three dimensions of space is an emergent property of matter. Only when the universe cools down to allow synthesis of matter does the three dimesnions of space appear. Indeed, if you have no matter you have no clocks, but you also fail to describe geometry.

 

Also, time is very much like the spatial dimension under certain conditions. What do you mean, time is not like the other dimensions through which we are able to move exactly? We are able to move in time, just in a very restricted way. Ok, in space, we are able to move freely left to right, back and forward, whereas in time it appears atleast in theory to be a forward-like motion without recourse. There are laws of physics which can change this aspect. Time becomes spacelike if you have the right kind of distortions around you. The fact space can become timelike, and time spacelike only strengthens how alike these two aspects are. Time is simply an imaginary leg of the space triangle. Time in theory is almost certainly an imaginary space dimension.

[MigL]

Sure and there are many more theories which have the three spatial and time dimensions as the left-over low energy dimensions. All the others curl up at low energies and disappear to below Planck scale. It is only at high energy ( Planck scale energy ) that these other dimensions , 10, 11, 26 or however many, manifest themselves.

 

Think of a two dimensional analogy of space; a rubber sheet with depressions where high mass-energu density is located. Move this sheet upwards at a rate of one second per second through the 'time dimension'. That is how time 'drags' us along as it moves in one direction only, towards the future. This is in effect an Einstein-Rosen embedding diagram moving in time. But keep in mind that the depressions in the sheet will grow and shrink depending on various time dilation effects.

[Mystery111]

Sure and there are many more theories which have the three spatial and time dimensions as the left-over low energy dimensions. All the others curl up at low energies and disappear to below Planck scale. It is only at high energy ( Planck scale energy ) that these other dimensions , 10, 11, 26 or however many, manifest themselves.

 

Think of a two dimensional analogy of space; a rubber sheet with depressions where high mass-energu density is located. Move this sheet upwards at a rate of one second per second through the 'time dimension'. That is how time 'drags' us along as it moves in one direction only, towards the future. This is in effect an Einstein-Rosen embedding diagram moving in time. But keep in mind that the depressions in the sheet will grow and shrink depending on various time dilation effects.

 

You seem to be suggesting time moves.... what is time moving relative to exactly?

 

See the problem is, is that time does not flow through us. We move through time. The appearance that time is linear comes from our perception of time. This does not mean it actually flows however.

[MigL]

I'm not suggesting time flows through us. Proper time marches on irrespective of observers. We do not get to choose the speed and direction of our motion through time as we do with tthe three spatial dimensions, rather we get dragged along with the flow of time, although the local flow can be modified somewhat by relativistic speeds and gravitational wells ( possibly even stopped such as at the event horizon of a black hole, ie the moving rubber sheet is 'pinned' at that point and stretches as the horizon stops moving through time. Although even to a non-local observer, Hawking radiation implies something is happening at the event horizon and so, even by your definition of time, it is actually still moving foreward ).

 

By the way, I'm not implying a single rubber sheet, but a multitude, one following another, and moving at the speed of proper time, such that the two dimensional foliations add up to form a 3D solid pillar, or in our real world case a 4D 'pillar' or shape of some kind. But certainly not a separate universe in the co-ordinate just vacated and moved into the past, as you seem to suggest in another thread.

Edited November 7, 2011 by MigL

[md65536]

I'm not suggesting time flows through us. Proper time marches on irrespective of observers. We do not get to choose the speed and direction of our motion through time as we do with tthe three spatial dimensions, rather we get dragged along with the flow of time,[...]

 

Yes, but what are you referring to when you say "we"?

A subatomic particle can behave as if it's moving backward or forward through time (if citation needed I'll try to find where Feynman explains this in his New Zealand lecture series... I can't remember exactly how he put it).

We as humans can't do this, but then again the particles that make us up can't move arbitrarily through spatial dimensions either. They get dragged along with the rest of our bodies.

 

So I'd say we move and perceive movement through both space and time not arbitrarily but as a coherent blob that places a lot of restrictions on us. These restrictions aren't necessarily fundamental aspects of space and time.

 

This doesn't say much about the nature of time. It's just an idea that we shouldn't make assumptions about how time and space work based on how we humanly perceive them to work.

 

 

[MigL]

I believe the phrase should read, certain types of subatomic particles can be treated mathematically AS IF they were travelling backwards through time. I don't think Feynman ever suggested that anti-particles really travel bacwards in time, nor that tachyons actually exist ( but, hey, stranger things have been discovered to happen ).

[md65536]

I believe the phrase should read, certain types of subatomic particles can be treated mathematically AS IF they were travelling backwards through time. I don't think Feynman ever suggested that anti-particles really travel bacwards in time, nor that tachyons actually exist ( but, hey, stranger things have been discovered to happen ).

The phrase should be a proper Feynman quote! I was referring to how interactions on Feynman diagrams can be pointed backward through time.

 

But yes, I think we're making the same point. At a quantum level, the behavior of things in time is described mathematically using the sums of probabilities of all possibilities (or whatever it is). At a macroscopic level it can be described the same, though you'll find that the probability of certain possibilities approach 1 and others approach 0, so you can also describe the behavior of macroscopic things in time with simplified math and deterministic equations.

 

There are different mathematical representations of time, I suppose... but then, how can you describe "what time is" using say only one representation and ignoring another? Ie describing time based on large bodies moving through space relative to each other, while ignoring quantum interactions?

 

I think that any "true" metaphysical understanding of time would have to correspond well with all "valid" mathematical representations of time.

As that pertains to the topic of this thread, my point is, I suppose, that assumptions about time that are made based on a limited domain, may only apply to that limited domain, and don't necessarily tell you anything about time across its entire domain.

[PeterJ]

Happened to notice this article just appearing on philpapers.com

 

 

Ernâni Magalhães (2011). Presentism, Persistence and Composition. Pacific Philosophical Quarterly 92 (4):509-523. (Direct link)

 

Pace Benovsky's ‘Presentism and Persistence,’ presentism is compatible with perdurantism, tropes and bundle-of-universals theories of persisting objects. I demonstrate how the resemblance, causation and precedence relations that tie stages together can be accommodated within an ersatzer presentist framework. The presentist account of these relations is then used to delineate a presentist-friendly account of the inter-temporal composition required for making worms out of stages. The defense of presentist trope theory shows how properties with indexes other than t may be said to exist at t. This involves an account of how times other than t exist at t, and how times may be multiply located at any given time. Benovsky's objection to bundles of universals is shown to assume that a bundle of properties must have the properties of its element properties.

 

[Mystery111]

I'm not suggesting time flows through us. Proper time marches on irrespective of observers. We do not get to choose the speed and direction of our motion through time as we do with tthe three spatial dimensions, rather we get dragged along with the flow of time, although the local flow can be modified somewhat by relativistic speeds and gravitational wells ( possibly even stopped such as at the event horizon of a black hole, ie the moving rubber sheet is 'pinned' at that point and stretches as the horizon stops moving through time. Although even to a non-local observer, Hawking radiation implies something is happening at the event horizon and so, even by your definition of time, it is actually still moving foreward ).

 

By the way, I'm not implying a single rubber sheet, but a multitude, one following another, and moving at the speed of proper time, such that the two dimensional foliations add up to form a 3D solid pillar, or in our real world case a 4D 'pillar' or shape of some kind. But certainly not a separate universe in the co-ordinate just vacated and moved into the past, as you seem to suggest in another thread.

 

TIME DOESN'T HAVE A FLOW!!!!!!

 

I think I have said this several times now. Maybe more.

Edited November 8, 2011 by Mystery111

[michel123456]

It is difficult to erase the "flow of time" from people's mind. It is the same hard as it is for someone to figure he is travelling at twice the speed of a Jumbo Jet while resting in a armchair on a beach at the equator.

[owl]

Mystery111, post 71

An eternal present simply means, the present time is all that is ever in existence.

 

This sums up the subject very succinctly. (I am bolding the present tense.)

 

But later, in post 75, he says:

Whilst the past is not happening right now, the past does have a now that is happening.

 

How can the past (no longer present) “have a now that is happening?” As per the “block universe” theory based on eternalism, in which the past and future are all somehow still present?

 

(I am hoping this post, directly on topic, in context, and specific to Mystery111’s comments, does not get me in trouble.)

[mooeypoo]

(I am hoping this post, directly on topic, in context, and specific to Mystery111's comments, does not get me in trouble.)

 

!

Moderator Note

You wrote this knowing it's not. This is a mainstream science thread, and it will deal with mainstream science, not your own theory.

Ending your off-topic posts with a disclaimer won't change the fact you're off topic and against the rules.

 

Stick to your thread, owl.

 

The rest, please get back on the original topic. If you want to discuss the implications of owl's theory, you can do so in the Speculation thread.

[MigL]

Yes, Mystery111, you have said 'time doesn't have a flow' many times now. But, I don't know , what's the minimum number of times you need to say it before it automatically becomes correct ???

 

We are having a discussion, an exchange of ideas if you will. The ideas I present are based on my limited knowledge, and are of course, opinions or best educated guesses ( based on GR ). Of course I cannot absolutely prove the assertions I've made, but at least I realise that. I also realise you cannot prove the assertions you've made, yet you claim that, since you've repeated them several times, they must be true.

 

An open mind is a terrible thing to be missing.

It cannot just be replaced by a donkey named Pompous.

[md65536]

Yes, Mystery111, you have said 'time doesn't have a flow' many times now. But, I don't know , what's the minimum number of times you need to say it before it automatically becomes correct ???

 

We are having a discussion, an exchange of ideas if you will. The ideas I present are based on my limited knowledge, and are of course, opinions or best educated guesses ( based on GR ). Of course I cannot absolutely prove the assertions I've made, but at least I realise that. I also realise you cannot prove the assertions you've made, yet you claim that, since you've repeated them several times, they must be true.

 

An open mind is a terrible thing to be missing.

It cannot just be replaced by a donkey named Pompous.

It doesn't become correct; either it was correct the first time, or not.

Perhaps if you explained what you mean when you're speaking of "the flow of time" then it might be possible to figure out if those ideas are correct or not.

Better yet, by explaining it as precisely as you can, you should be able to better understand your own ideas, and to tell if they are even meaningful and/or make sense. Then, if "flow" is the best word for your idea, you could explain its meaning. If not, you might find more meaningful words to express your ideas.

 

The ability to reason about things that you don't fully understand is a sign of an open mind. Avoiding understanding by hiding it behind possibly meaningless words, whether they're your words or others, is not.

 

Do you wish to continue being pedantic, or are you interested in a serious discussion?

I don't think pedantry is a bad thing in a conversation like this. At best everyone would be using words that have the same meaning to everyone. More common, not only are people using words that mean different things to different people, but often don't even mean anything useful to the person using them.

 

An "exchange of ideas" is good. It's not as useful if nobody knows what anyone is talking about.

 

 

[MigL]

Excuse-me but shouldn't you be lecturing him about an open mind ??

I'm not the one who screamed at him " TIME DOESN'T HAVE A FLOW!!!!!! "

 

And if you're unhappy with time flow, then it progresses, advances, moves foreward,etc. Don't make me get out my dictionary.

The point I'm making is that everything is carried along with it. We do not move along a'yardstick' of time since then there would be no repercussions to moving faster or slower or even backwards along this 'yardstick'. Causality has to be preserved or else the universe stops making sense.

[md65536]

I believe the phrase should read, certain types of subatomic particles can be treated mathematically AS IF they were travelling backwards through time. I don't think Feynman ever suggested that anti-particles really travel bacwards in time, nor that tachyons actually exist ( but, hey, stranger things have been discovered to happen ).

Yes, I think you must be correct.

The best reference I could find so far is here: http://vega.org.uk/video/programme/47 If you skip to 92:23 (and watch to the end), Feynman answers a few questions concerning time. He mentions some topics that are probably very useful to an understanding of time, and related to the questions of this thread, but I don't see any unambiguous answers that couldn't be interpreted either way.

 

 

Note: 92:23 specifically addresses causality.

Edited November 9, 2011 by md65536

[DrRocket]

I wasn't so surprised to read Dr Rockets analysis on the situation. When I first came here, I began to teach time in accordance to (but not fully) presentism. I don't support all the views held by it, but what I did understand was there could only be an eternal present. This is true to physics and what is a relative fact is that past and future ceased to exist. Time as we knew it began to vanish from the theory and did completely vanish when taken to scales of the universe - this is the way it is because of a known constraint of the universe Hamiltonian called the Wheeler de Witt equation. It succesfully describes a non-changing universe, where time no longer can describe moving clocks.

 

Dr. Rocket said ''utter nonsense'' in response, and I said to him he was entitled to his own opinion on the subject, but it wasn't taken any further. So as much as you were surprised, I knew he didn't like presentism or an eternal present at all.

 

In general relativity there is no such think as a global time. Time is a local notion only. The time measured by clocks is proper time, and there is a proper time associated with each world line. You cannot compare "time here" with "time there" except as a local, coordinate-dependent approximation.

 

In this regard the special theory of relativity is misleading until one recognizes that special relativity is simply the local approximation to general rrelativity, special relativity really applies on the tangent space to the spacetime manifold and not to the manifold itself. It works very well on small and modest scales, but not at all in the current context.

 

So, there is no such thing as a "universal present" which makes "presentism" rubbish..

 

You can, and apparently are, confusing yourself by using global models from cosmology that use a universal notion of time. This is justified by assuming that the universe is homogeneous and isotropic, in which case spacetime decomposes as a one-parameter foliation of spacelike hypersurfaces ("space") by a timelike parameter ("time"). This decomposition is not unique, and in fact exists only as an approximation on the largest scales. The universe is manifestly neither truly homogenous nor isotropic, though the contrary assumption is a useful fiction in cosmology.

 

So, you can stop your bluff and your typical attempt to baffle with bullshit. It is quite easy to see through your arguments, which have no content -- just a lot of buzz words that you fail to truly understand. The Wheeler De Witt equation and all manner of failed attempts at quantum gravity are quite irrelevant.

[Mystery111]

In general relativity there is no such think as a global time. Time is a local notion only. The time measured by clocks is proper time, and there is a proper time associated with each world line. You cannot compare "time here" with "time there" except as a local, coordinate-dependent approximation.

 

In this regard the special theory of relativity is misleading until one recognizes that special relativity is simply the local approximation to general rrelativity, special relativity really applies on the tangent space to the spacetime manifold and not to the manifold itself. It works very well on small and modest scales, but not at all in the current context.

 

So, there is no such thing as a "universal present" which makes "presentism" rubbish..

 

You can, and apparently are, confusing yourself by using global models from cosmology that use a universal notion of time. This is justified by assuming that the universe is homogeneous and isotropic, in which case spacetime decomposes as a one-parameter foliation of spacelike hypersurfaces ("space") by a timelike parameter ("time"). This decomposition is not unique, and in fact exists only as an approximation on the largest scales. The universe is manifestly neither truly homogenous nor isotropic, though the contrary assumption is a useful fiction in cosmology.

 

So, you can stop your bluff and your typical attempt to baffle with bullshit. It is quite easy to see through your arguments, which have no content -- just a lot of buzz words that you fail to truly understand. The Wheeler De Witt equation and all manner of failed attempts at quantum gravity are quite irrelevant.

 

 

It's very close to being homogeneous; It is homogeneous to 100,000th of an error in each direction of spacetime we observe.

 

So, you can stop your bluff and your typical attempt to baffle with bullshit. It is quite easy to see through your arguments, which have no content -- just a lot of buzz words that you fail to truly understand. The Wheeler De Witt equation and all manner of failed attempts at quantum gravity are quite irrelevant.

 

Ahem... anyway... I do understand what the Wheeler de Witt equation is. And it may seem like buzzwords, but I know it acts as a solution to the EFE's and the wave function it describes is the wave function of the universe.

 

Bing Bang Bosh.

 

Mystery111, post 71

 

 

This sums up the subject very succinctly. (I am bolding the present tense.)

 

But later, in post 75, he says:

 

 

How can the past (no longer present) "have a now that is happening?" As per the "block universe" theory based on eternalism, in which the past and future are all somehow still present?

 

(I am hoping this post, directly on topic, in context, and specific to Mystery111's comments, does not get me in trouble.)

 

Owl I've opened up a thread on time, take the qoute up there and I will answer it, if I can.

 

Yes, Mystery111, you have said 'time doesn't have a flow' many times now. But, I don't know , what's the minimum number of times you need to say it before it automatically becomes correct ???

 

We are having a discussion, an exchange of ideas if you will. The ideas I present are based on my limited knowledge, and are of course, opinions or best educated guesses ( based on GR ). Of course I cannot absolutely prove the assertions I've made, but at least I realise that. I also realise you cannot prove the assertions you've made, yet you claim that, since you've repeated them several times, they must be true.

 

An open mind is a terrible thing to be missing.

It cannot just be replaced by a donkey named Pompous.

 

It's the quantum mechanical view. How more correct could it be?

 

So, there is no such thing as a "universal present" which makes "presentism" rubbish..

 

 

Doctor Rocket maybe I will call your bluff afterall.

 

You have admitted yourself that time description is a local event. It is also a local, real variable. Events only ever happen in the present moment and observations made in real time. Perhaps you would like to tell me why a universal present is ''obsurd.''

 

With all the evidence that everything exists inside the present sphere, what evidence do you have other than saying time is not global that presentism, or certain fascets of it are.... simply hogwash? I know you have strong opinions about this, we've clashed before on the subject, so I hope you can recite references and whatnot.

Edited November 9, 2011 by Mystery111

[DrRocket]

It's very close to being homogeneous; It is homogeneous to 100,000th of an error in each direction of spacetime we observe.

 

That is not homogeneity. It is isotropy.

 

"to 100,000th of an error" is meaningless.

 

It is also irrelevant to the issue at hand. More buzz words that you don't understand.

[md65536]

So, there is no such thing as a "universal present" which makes "presentism" rubbish..

Who said that presentism implies a universal present?

 

Isn't there some middle ground, where we can say that the universe as a whole cannot be described with presentism, because there is no one "knife edge" surface separating the past and the present. But any single observer can describe the universe observationally using presentism, because they have defined (or can choose?) such a surface?

 

I don't think it's a problem that presentism may or may not be compatible with reality depending on what you're talking about, because a "universal" description of time (as part of a 4d manifold or whatever) is very different from time as defined by an observer or observational point of view? And isn't "the present time" only defined relative to a specific frame of reference?

 

 

[Mystery111]

That is not homogeneity. It is isotropy.

 

"to 100,000th of an error" is meaningless.

 

It is also irrelevant to the issue at hand. More buzz words that you don't understand.

 

I know what it means, it's quite clear you haven't a clue. And homogeneity is perfectly correct, in the way I was using it. In what sense are you using it?

[swansont]

More buzz words that you don't understand.

 

I know what it means, it's quite clear you haven't a clue.

 

!

Moderator Note

Let's stop with this right now and stick to the discussion, which — let me remind all — was posted in the physics section. Perhaps someone could take up the banner of discussing how "the present" (or "it's always now") isn't a tautology and can be quantified, in keeping with sound physics principles