# Does the time exist?

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What is time?

The operational definition of assigning a time to an event as mentioned by A. Einstein in his 1905 paper is essentially what it is, and how it's been done since humans appeared.

It is a correspondence convention, i.e., assigning events of interest to standard clock events, a measure and ordering of activity, with 'time' always increasing/accumulating.

It is an accounting scheme developed out of practical necessity, for human activities like agriculture, business, travel, science, etc. The unit of measure for time initially referred to relative positions of astronomical objects, stars, sun, and moon, which implies earth rotations and earth orbits. All units of time are by definition, involving spatial motion or distance. The clock further divides the day into smaller units of measure. Current scientific research requires clocks that generate smaller and more precise periods than those of the past. The second is defined as n wave lengths of a specific frequency of light, a distance, but labeled as "time".

If we use a light based clock to time the speed of an object along a known distance x, what are we actually doing?

We are comparing the simultaneous motion of an object to the motion of light for a duration (number of cycles). The result is a ratio x/s = vt/ct = v/c or speed. It should be obvious that the number of cycles serves to correlate the positions of the object with the positions of the light signal, for simultaneous comparisons. If you use Minkowski spacetime diagrams the vertical scale is not 'time', but ct, light path distance, i.e. they plot speed. This allows a simple comparison of equivalent entities, without consideration of the nature of those entities. The scaling of the time variable by c allows an analysis of extremely short durations of time.

quotes by the author of SR

From 'The Meaning of Relativity', Albert Einstein, 1956:

page 1.

"The experiences of an individual appear to us arranged in a series of events; in this series the single events which we remember appear to be ordered according to the criteria of "earlier" and "later", which cannot be analyzed further. There exists, therefore, for the individual, an I-time, or subjective time."

page 31.

"The non-divisibility of the four-dimensional continuum of events does not at all, however, involve the equivalence of the space coordinates with the time coordinate."

page 32.

"Finally, with Minkowski, we introduce in place of the real time co-ordinate l=ct, the imaginary time co-ordinate..."
[This does not mean 'time' is literally imaginary. The 'i' in the complex plain indicates a coordinate independent of the others, when (x, y, z) are present.]

time and perception
Subjective time requires memory, which allows a comparison of a current state to a previous state for any changes, which lends itself to an interpretation of time flowing.

Patients with brain damage to specific areas involved in maintaining a personal chronology, lose their ability to estimate elapsed time, short or long term. Consider the fact that people waking from a comatose state, have no memory of how much elapsed time, whether hrs, days, or even years.

Consider one of the greatest misnomers ever used, 'motion pictures' or 'movies', where a person observes a sequence of still photos and the mind melds them to produce moving objects where there is no motion. These cases show time as part of perception. Special Relativity then predicts alteration of measurement and perception via motion.

misc.
It was Minkowski who advocated the mathematical manipulation of the expression for the invariant interval from an equality to a generalized form of four variables, producing spacetime. I refer to the Minkowski version of SR as a 'lines on paper' theory. Time is represented as a line, removing any attributes that would distinguish its identity from other variables, a line is a line.

Math equations that express a behavior as a function of time, are misleading when the time is interpreted as a causative factor. The time of an event must be assigned after the event occurs, i.e. after awareness! If a nova is observed in 2010, and is 100 ly distant, it didn't happen because it was 1910 on earth. It was the physical processes already in place that reacted to an unstable state. A person dies, not because it's his 'time', but because his biological system reaches a state that can't be maintained.

Which brings us to the real issue (for me) perpetuating the millenia of debating 'time'.
No one wants to be informed "atomic clock at NIST has a hole in it and time is running out". Time implies longevity. People gain some sense of security if they think there is an invisible entity behind the scenes arranging and scheduling more events.
Time is not an issue for physics but for psychology.

Source: 15 years participating in forum debates, and Scientific American, 'A Matter of Time', vol. 287, 2002.

Edited by phyti

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3 hours ago, phyti said:

Which brings us to the real issue (for me) perpetuating the millenia of debating 'time'.
No one wants to be informed "atomic clock at NIST has a hole in it and time is running out".

That’s just silly

Source: me, who worked for ~25 years at the US Naval Observatory in the precise time department

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1 hour ago, swansont said:

That’s just silly

Source: me, who worked for ~25 years at the US Naval Observatory in the precise time department

Your explanations on time over the years has always been internally consistent, in my opinion.

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Does time exist ?

It exists in the same way length, width and height exist.
We measure length with rulers, which are a length.
Similarly, we measure the passing of time with an ideal clock, which is the passing of time.
But no one seems to ask "What is length ?"
Yet all four concepts, time, length, width and height are indispensable as tools to describe our world.

Or is it a problem with the meaning of 'exist' ?
One could argue that the chair you're sitting on does not exist.
After all, one of the most successful theories of modern Science suggest that chair is made up of nothing but fields, which are themselves, nothing butquantities assigned to each point in space.
Butwhether the chair 'exists' or not ( according to Quantum Field Theory ), there is no denying that the theory does provide useful information and valid predictions about that chair and how it behaves.

So, does 'exist' refer to what something is, or does it refer to how it behaves ?

Edited by MigL

Does time exist?

Yes, it does.

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On 1/11/2024 at 10:58 AM, Genady said:

Does time exist?

Yes, it does.

Of course, how else can we stop everything from happening at once...

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swansont;

Source: me, who worked for ~25 years at the US Naval Observatory in the precise time department

And NIST provides the time standard for anyone who needs it.

A process that measures 9 billion+ microwave cycles to define the second.

I.e. the standard is man-made, a convention. Not an independent entity like an em or gravitational field, or a particle.

From birth to death, you have a paper trail, all timestamped.

No one has time in a bottle.

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3 minutes ago, phyti said:

No one has time in a bottle.

No one has distance in a bottle, either. So what?

”Hey barkeep! Give me a pint of centimeters and a plate full of inches, please.”

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5 minutes ago, phyti said:

swansont;

Quote

And NIST provides the time standard for anyone who needs it.

So does USNO, via GPS.

Time from USNO and NIST typically agree to better than 100ns (often much better); there’s a memorandum of understanding that dictates how well.

Quote

A process that measures 9 billion+ microwave cycles to define the second.

I.e. the standard is man-made, a convention. Not an independent entity like an em or gravitational field, or a particle.

How is this different from other base unit standards, like length, which is defined in terms of how far light travels in a second? They’re all conventions.

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Time slows down upon closing in on the speed of light or getting closer to massive objects! Does that not make it a bit more elusive than length?

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33 minutes ago, Luc Turpin said:

Time slows down upon closing in on the speed of light or getting closer to massive objects! Does that not make it a bit more elusive than length?

Length changes, too, under those circumstances

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On 7/2/2021 at 2:19 AM, Heis3nberg said:

If we try to shoot a bullet, we can calculate his speed, linear momentum, the Force with which he exits from the gun and exc..; we could also "see" these phisical parametres and decree their presence. But, what about the time? It is undetectable, maybe because it is only an illusion...

Take your watch, you can see the second hand which is ticking; A second passes, but we haven't seen the time yet, we can only decree that second hand has made a circular movements of four degrees. The physics laws of the nature would be the same if we considered that a circulare movement of 4 degrres of the second hand of very watch is equal to one second...

...but there is movement. Unless you don't detect movement at all, you still have these intervals that you can characterize as a form of time. Perception doesn't work in instants. If you have any kind of detection, that detection itself contains movement of some sort, otherwise there's no detection at all.

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1 hour ago, swansont said:

Length changes, too, under those circumstances

2 hours ago, swansont said:

Length changes, too, under those circumstances

So, both time and length are more malleable than what every day experience tells us. Also, length does not affect us as much as time; we are late for a meeting; we have a few years left to live, etc. I think that that is why, at least perceptually, we are more invested in time then length; unless you are a carpenter. On another matter and theoretically, if time stands still and length compresses (I guess) to a point of nothingness, do we come to a point where space-time ceases to exist? As in a singularity?

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31 minutes ago, Luc Turpin said:

length does not affect us as much as time

My wife begs to differ

33 minutes ago, Luc Turpin said:

if time stands still and length compresses (I guess) to a point of nothingness, do we come to a point where space-time ceases to exist?

Until you explain the mechanism by which those two events come to pass, they can be treated as fictional and have any fictional answer you prefer.

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17 minutes ago, iNow said:

My wife begs to differ

Crude, but good one😆

17 minutes ago, iNow said:

Until you explain the mechanism by which those two events come to pass, they can be treated as fictional and have any fictional answer you prefer.

Just before the big bang, falling into a black hole, does space-time ceases to exist?

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59 minutes ago, Luc Turpin said:

So, both time and length are more malleable than what every day experience tells us.

Yes, that was the revelation of Einstein’s relativity, back in 1905.

59 minutes ago, Luc Turpin said:

Also, length does not affect us as much as time; we are late for a meeting; we have a few years left to live, etc. I think that that is why, at least perceptually, we are more invested in time then length; unless you are a carpenter.

We perceive length visually, geometrically. Time, not so much.

59 minutes ago, Luc Turpin said:

On another matter and theoretically, if time stands still and length compresses (I guess) to a point of nothingness, do we come to a point where space-time ceases to exist? As in a singularity?

There’s no physics that describes time standing still and contracting length to zero. The equations fail under that scenario.

13 minutes ago, Luc Turpin said:

Just before the big bang, falling into a black hole, does space-time ceases to exist?

Before the big bang is another thing that physics can’t describe.

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6 minutes ago, Luc Turpin said:

Just before the big bang,

This is meaningless. We can't know anything about the universe before the BB.

7 minutes ago, Luc Turpin said:

falling into a black hole, does space-time ceases to exist?

Spacetime is what becomes so extremely distorted that, beyond the event horizon, there is no way to navigate anywhere but towards the degenerate matter. In a spaceship in normal spacetime, the gravitational attraction from a sun is something you can compensate for by firing your thrusters, using more thrust the closer you are to the sun so you don't fall in, using any of a number of directions to take you away from the sun. But once you move beyond the event horizon of a collapsed sun (black hole), spacetime is so badly warped that no other courses are available to you except straight in. We can't observe exactly what happens, but the math says no amount of energy expended can overcome how distorted spacetime is inside a black hole.

This isn't a very technical explanation, so I hope it doesn't lead you further into the weeds. Spacetime becomes extremely curved in the presence of the degenerate matter, but of course it doesn't cease to exist.

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2 hours ago, Luc Turpin said:

Just before the Big Bang <snip>, does space-time ceases to exist?

That which does not yet exist cannot cease to

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1 hour ago, Phi for All said:

This is meaningless. We can't know anything about the universe before the BB.

Spacetime is what becomes so extremely distorted that, beyond the event horizon, there is no way to navigate anywhere but towards the degenerate matter. In a spaceship in normal spacetime, the gravitational attraction from a sun is something you can compensate for by firing your thrusters, using more thrust the closer you are to the sun so you don't fall in, using any of a number of directions to take you away from the sun. But once you move beyond the event horizon of a collapsed sun (black hole), spacetime is so badly warped that no other courses are available to you except straight in. We can't observe exactly what happens, but the math says no amount of energy expended can overcome how distorted spacetime is inside a black hole.

This isn't a very technical explanation, so I hope it doesn't lead you further into the weeds. Spacetime becomes extremely curved in the presence of the degenerate matter, but of course it doesn't cease to exist.

I should have said at the moment of the big bang instead of before. With the big-bounce theory (conformal cosmic cosmology) I believe that there is a before the big bang. The reason why I was inquiring about spacetime was to determine whether or not there existed conditions, even extreme ones, where time does not exist, which is the question raised for the tittle of this thread.  Length came along for the ride as both space and time are intertwined. So, in your answer, time still exists, but is warped. So, time always exists.

2 hours ago, swansont said:

Yes, that was the revelation of Einstein’s relativity, back in 1905.

We perceive length visually, geometrically. Time, not so much.

There’s no physics that describes time standing still and contracting length to zero. The equations fail under that scenario.

Before the big bang is another thing that physics can’t describe.

First line - Knew about time being maleable, but not length. I confess.

Second line - well said

Third line - was looking for conditions where time did not exists; it is always there, even in extreme conditions.

Fourth line - as mentioned above, should have said at the big bang and not before it.  I think that this makes a difference as we are talking about a singularity are we not?

5 minutes ago, iNow said:

That which does not yet exist cannot cease to

Well said also

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20 minutes ago, Luc Turpin said:

Fourth line - as mentioned above, should have said at the big bang and not before it.  I think that this makes a difference as we are talking about a singularity are we not?

Our physics descriptions are valid back to about 10^-43 sec. Not to zero.

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2 hours ago, Phi for All said:

Spacetime is what becomes so extremely distorted that, beyond the event horizon, there is no way to navigate anywhere but towards the degenerate matter. In a spaceship in normal spacetime, the gravitational attraction from a sun is something you can compensate for by firing your thrusters, using more thrust the closer you are to the sun so you don't fall in, using any of a number of directions to take you away from the sun. But once you move beyond the event horizon of a collapsed sun (black hole), spacetime is so badly warped that no other courses are available to you except straight in. We can't observe exactly what happens, but the math says no amount of energy expended can overcome how distorted spacetime is inside a black hole.

This isn't a very technical explanation, so I hope it doesn't lead you further into the weeds. Spacetime becomes extremely curved in the presence of the degenerate matter, but of course it doesn't cease to exist.

It's worth pointing out that although for a small black hole, the tidal forces may be so intense as to cause "spaghettification" well outside the event horizon, for an extremely large black hole, the tidal forces may be so weak that one might not even be aware that one has crossed the event horizon.

Also, black holes have a peculiar property compared to ordinary matter: the mass of a black hole increases linearly with respect to radius, in contrast to the cube-power for ordinary matter. Thus, extremely large black holes have very low density. One only needs to accumulate enough matter into the large volume to form the large black hole... one doesn't need to compress anything.

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1 hour ago, swansont said:

Our physics descriptions are valid back to about 10^-43 sec. Not to zero.

Thank for the precision. I have my answer, time always exists.

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2 hours ago, KJW said:

It's worth pointing out that although for a small black hole, the tidal forces may be so intense as to cause "spaghettification" well outside the event horizon, for an extremely large black hole, the tidal forces may be so weak that one might not even be aware that one has crossed the event horizon.

Also, black holes have a peculiar property compared to ordinary matter: the mass of a black hole increases linearly with respect to radius, in contrast to the cube-power for ordinary matter. Thus, extremely large black holes have very low density. One only needs to accumulate enough matter into the large volume to form the large black hole... one doesn't need to compress anything.

Is there a limit to how large and how "undense" such an object can become?

Less dense than the surrounding  region ,for example?

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I investigated the matter of time further and the prevailing consensus is that it began 10^-43 sec after the Big Bang, does exist and does not stop, even in a black hole. However, there are dissenting voices for all of these statements. Some make a case for something being there before the Big Bang, that time does not really exist and that it does stop at the center of a black hole. Let us be reminded that even in science that are no unshakeable truths.

“At the very center of the black hole is where our understanding breaks down. Einstein's theory of gravity seems to predict that time itself is destroyed at the center of the hole: time comes to an abrupt end there. For this reason, a black hole is sometimes described as the "reverse of creation." But no one knows how or why time could come to an abrupt end, any more than we know how time was created in the first place. Einstein's theory of gravity no longer applies at these tiniest scales of distance, and new laws of nature must be found that describe what happens at the center of a black hole.”

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15 hours ago, geordief said:

Is there a limit to how large and how "undense" such an object can become?

Less dense than the surrounding region, for example?

Considering the Schwarzschild metric, there is no upper limit to mass, and therefore no limit to the size and how close to zero the density can be. However, there may be limits at the cosmological scale. For example, I doubt that a black hole can be less dense than the universe as a whole.

If the region surrounding a black hole is denser than the black hole, then the total mass of the black hole and the surrounding region would be large enough for the surrounding region to be also inside the black hole.

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