# What is time?

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What exactly is time?

The International System of Units (SI) defines the second as 9,192,631,770 cycles of the radiation, which corresponds to the transition between two hyperfine energy levels of the ground state of the 133Cs atom.

^taken from wikipedia^

Is there really such thing as time or is it just something we put in place of something we do not know how to answer?

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Just as distance is the separation between objects, duration is the separation between states of a system. Time and space are more similar than most people think. They are both relative and their magnitude is dependent on the energy in a reference frame.

There is a difference between the definition of a second(a unit of duration) and time itself.

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You can ask the exact same question of other fundamental quantities such as distance. Time and distance are axiomatic in physics.

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Just as distance is the separation between objects, duration is the separation between states of a system. Time and space are more similar than most people think. They are both relative and their magnitude is dependent on the energy in a reference frame.

Really? How is space relative?

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Really? How is space relative?

Length contraction at relativistic speeds.

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can you explain how time is relative? I guess I don't see how.

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can you explain how time is relative? I guess I don't see how.

Observers in different inertial frames and/or gravitational potentials will measure time passing at different rates.

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Don't take the radiation example as the true definition of time. In effect, you can work on much shorter distances, such as a billionth part of a billionth part of the billionth part of the billionth part of the billionth part of one second, which normal matter is seen to exist in, in a smallest unit of time.

The ''second'' is almost CERTAINLY man-made. It maybe just be coincidence that radiation has a specific law under the second, but i can assure you, time is not invariant under radiation. Radiation is physical, time is not. In fact, it's a terrible analogy made by the international standard units.

Time might not even exist.

Stuart Hammeroff in a recent interview i had watched, noted a discussion between himself and another physicist. They had argued on the nature of backwards in time travel, but the one thing they could agree on was that without the mind, there is no time.

''Time HAS a distinctive flow'' Stuart says, ''And without the mind there, there seems to be no flow...''

This flow has universally been called, ''the psychological arrow of time,'' and it represents the very linear nature of perception. But of course, nature and more importantly time itself, is not linear at all. Some call this linearization, a westernized ''popularity of order.'' It does seem that we have conditioned our views on time to be strictly linear, whilst other civilizations continue to teach that time is not.

In physics, we learn that time is in fact a fleeting, short snaps of existence, flashing in and out of reality, but our perception is what ''binds'' these flashes together. We somehow crystalize reality into a smooth, homogeneous set of frames, when really, there is no reference to these frames, and all reality might as well just exist in one big flash.

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Don't take the radiation example as the true definition of time. In effect, you can work on much shorter distances, such as a billionth part of a billionth part of the billionth part of the billionth part of the billionth part of one second, which normal matter is seen to exist in, in a smallest unit of time.

The ''second'' is almost CERTAINLY man-made. It maybe just be coincidence that radiation has a specific law under the second, but i can assure you, time is not invariant under radiation. Radiation is physical, time is not. In fact, it's a terrible analogy made by the international standard units.

The second is most definitely man-made. As is the meter, the Coulomb, the Kelvin, the gram and a whole host of other units. Defining a standard of time, the second, is not the same as explaining the nature of time. "Analogy" is, I think, a completely incorrect description of the situation — the former is physics/metrology and the latter is metaphysics.

Time might not even exist.

Stuart Hammeroff in a recent interview i had watched, noted a discussion between himself and another physicist. They had argued on the nature of backwards in time travel, but the one thing they could agree on was that without the mind, there is no time.

''Time HAS a distinctive flow'' Stuart says, ''And without the mind there, there seems to be no flow...''

This flow has universally been called, ''the psychological arrow of time,'' and it represents the very linear nature of perception. But of course, nature and more importantly time itself, is not linear at all. Some call this linearization, a westernized ''popularity of order.'' It does seem that we have conditioned our views on time to be strictly linear, whilst other civilizations continue to teach that time is not.

Hameroff is a physicist? Wikipedia list him as an anesthesiologist

http://en.wikipedia.org/wiki/Stuart_Hameroff

Once consciousness enters the discussion, I think you have left the field of physics.

In physics, we learn that time is in fact a fleeting, short snaps of existence, flashing in and out of reality, but our perception is what ''binds'' these flashes together. We somehow crystalize reality into a smooth, homogeneous set of frames, when really, there is no reference to these frames, and all reality might as well just exist in one big flash.

I think physics teaches no such thing. On the contrary, in physics we learn not to depend on our perception, since we want objective measurement.

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Sorry -- Stuart is not a physicist, though he does deal greately in physics, and well deserves to be called one.

''I think physics teaches no such thing. On the contrary, in physics we learn not to depend on our perception, since we want objective measurement.''

Not entirely true. Physics is arising with the notion right now that time is how i described it. As i said, i watched a documentary not long ago with Stuart in it, talking about his conversations with another physicist, and they came to agree that time was flashes. Then, only about half a year ago, i remember reading work by Fred Wolf, a theoretical scientist in the area of physcology and mind, and he pretty much said the same thing too. So yes, i am sure this is what we are taught, if studying this area.

However an objective measurement is radical and needed, but moreover, time can still exist as a ghost of the mind, and nothing in reality is vastly changed, other than the equations that describe it. Without time, there might still be movement. Time just seems to be something we use to take note of things that pass us by. There is really no evidence to suggest it exists independantly of the mind at all. Even movement.

(Oh yes... and Tipler also created an independant theory, where reality flashed in and out of existence.)

multiple post merged
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So basically we're all wrong about our ideas? Or is it that we don't know? Like as in the fourth dimension, we just can't see it but we can sort of prove it's there.

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Well, the fourth dimension isn't needed in physics. We can make perfectly good physics out of a Euclidean Space. As for time being proven, its very hard. We know ''we'' sense time, but whether anything else experiences a time, is up for debate.

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Well, the fourth dimension isn't needed in physics. We can make perfectly good physics out of a Euclidean Space.

And yet we do use it, and we don't do physics in Euclidean space except as an approximation (which is usually valid). So there would seem to be a contradiction here. Care to elaborate?

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That's because in schools we universally use four dimensions. It's not a parlour trick, where we can magically use four dimensions, and no longer three. If push came to shove, we could use three, without the four. We did it for a long time without the aid of Minkowski and his generalization of four vectors.

Then there was Eddington, who clearly helped Einstein get to the top, but even he said four dimensions seemed crazy.

Again, we only use four dimensions because there is no educational system which doesn't teach that time isn't the fourth dimension. Now ask yourself why time is the fourth dimension, and if you don't know, i will tell you.

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what if time wasnt the fourth dimension though?

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Well, it would mean that we have strained our equations a bit too much. It would mean that time is not a physical vector, and that things can evolve quite perfectly without its description.

It wouldn't be a disaster for physics, but it would a new way to look at everything. The way things, might i stress, was looked upon before Minkowski's input.

It just means, that time would no longer be a dimension as such, but would remain a totally psychological aspect of the human experience.

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I see, I see

How possible is it though, as Tsadi said that time could not be a physical vector?

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Really? How is space relative?

Observers in different inertial frames and/or gravitational potentials will measure time passing at different rates.

Can someone explain how space is relative in the same visual manner as the explanation above for how time is relative?

I don't understand "Length contraction at relativistic speeds."

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Can someone explain how space is relative in the same visual manner as the explanation above for how time is relative?

I don't understand "Length contraction at relativistic speeds."

The coordinate system you use to measure length depends on speed. Space isn't Cartesian. Length isn't an absolute.

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Basically, my meter is not the same is your meter if we are moving at different speeds (and subject to different velocities and potentials).

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Now ask yourself why time is the fourth dimension, and if you don't know, i will tell you.

We put time on (almost) the same footing as space because it makes good sense to do so. The resulting structures are representations of the Poincare group and space-time has a larger symmetry than space alone. In physics we usually seek to describe things in as simple and connected ways as possible. Pretty much all the fundamental theories we have are simpler to write down in 4d space-time than in some manifestly non-covariant form.

Maxwell's equations in vacuo spring to mind as an example.

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I still look at time as really being an abstract measurement of motion. Motion being the real physical property being observed here.

Couldn’t we just replace the word 'time' with the word 'motion' and operate just as effectively (if not more)? With the exception that we can actually see motion and its effects – decay, movement, speed, growth, etc. Whilst time remains a greek myth of sorts, possibly a contemporary delusion?

I mean, cycles of the radiation used to define time is movement in itself?

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I was recently notified elsewhere by an ongoing essay contest on the topic: the nature of time, arranged by FQXi community.

See all the essays at

http://fqxi.org/community/forum/category/10

Some very famous people has written essays for this competition, including Carol Rovelli. All the essays are intended as easy reading and I think they are all at most 10 pages each.

Click on each title and you can download the essay as a pdf and read!

The topic of those essays are right in line with the topic of this thread.

/Fredrik

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I still look at time as really being an abstract measurement of motion. Motion being the real physical property being observed here.

Couldn’t we just replace the word 'time' with the word 'motion' and operate just as effectively (if not more)? With the exception that we can actually see motion and its effects – decay, movement, speed, growth, etc. Whilst time remains a greek myth of sorts, possibly a contemporary delusion?

I mean, cycles of the radiation used to define time is movement in itself?

Not really. In quantum mechanics is usually dangerous to assume a classical behavior explanation. An superposition of two states in one basis does not mean there is motion.

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An superposition of two states in one basis does not mean there is motion.

Does a 'superposition of two states in one basis' mean there is time, in QM?

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