Is Spacetime a Reality

[Onoma]

The reason I brought up quantitative VS qualitative was because of what I read about Einstein's problems with the concept of " now " and how this relates to the question of " Is time discrete ? " ( Quantized time is not equal to discrete time )

You'd think this was settled by the work of Planck and Stoney, et al , yet we find physicists like Hawking invoking sub-Planck units in his work on BH radiation, and generally to my knowledge, this question has not been conclusively answered

 

[Tambourine]

Does spacetime exist as a physical reality?
Or is spacetime accepted as a reality because of its ability to accurately predict physical reality?

What's the difference difference between these two questions?

If spacetime is a physical reality, does this mean the past and future exist concurrently with now as physically realities?

Past, present and future are not separate physical "realities", and I don't understand how you would infer that from the existence of spacetime.

 

[Tambourine]

Please define what is "now", "today". What does it mean "today is 2020 AD?"
The definition is a tautology: today is what we see on the calendar today.

"Now" is what we subjectively experience as present, "today" is a social construct we created to faciliate economic, social and political exchanges.

 

[ChristineM]

Well, I'm lost then

I consider qualitative to be not measurable

I see it as a measure of the quality of something

 

[Nakosis]

What's the difference difference between these two questions?

I don't think just because we construct a model of reality that can accurately predict reality that the model physically exists.

The model/construct of spacetime is necessary to allow accurate calculations of physical reality. It has been implied to me before that this makes it necessary for spacetime to actually exist. The second question, questions this need.

Past, present and future are not separate physical "realities", and I don't understand how you would infer that from the existence of spacetime.

I'm thinking in terms of multidimensions. The past and future exist as coordinates in spacetime. We experience now as a sequential passage through these coordinates. This would allow the possibility of time travel. We could travel to a spacetime coordinate to visit a past, our past.

Is time travel science fiction or science fact IOW.

 

[Nakosis]

approximately.....one tenth of one second

it takes that long for the nervous system to send the signal to your brain

to respond even in reflex.....one tenth more

so some reflexes like touching something hot
sends a signal to the elbow and your elbow will jerk
quicker than your brain will say.....OW!

but time was not a force applied in that event
because time is not a force

In my view time means change. So by the time we are consciously aware of reality, reality has changed to something else.
So change is not a force, it is every force. Ever force that keeps reality in a constant state of change.

 

[McBell]

I see it as a measure of the quality of something

I agree.
I will go further and say that since quality is purely speculative there are a lot of various means,, scales, etc used to measure it.
Thus giving the illusion it can not be measured.

 

[McBell]

In my view time means change. So by the time we are consciously aware of reality, reality has changed to something else.
So change is not a force, it is every force. Ever force that keeps reality in a constant state of change.

I see time as the tool used to measure the change, not change itself.

 

[Nakosis]

Albert is quoted to say.....

Time is an illusion

I don't think Einstein actually said time was an illusion. What he said was,

Now he has departed from this strange world a little ahead of me. That means nothing. People like us, who believe in physics, know that the distinction between past, present and future is only a stubbornly persistent illusion.

Seems like perhaps he meant the past present and future somehow concurrently exist. So if you lose someone they actually continue to exist as part of the space-time continuum.

 

[Nakosis]

I see it as a measure of the quality of something

I measure quality all the time, by the number of defects.
I don't know if that is helpful but quality can be measure in certain instances.

 

[Yerda]

The greatest trick the universe ever pulled was convincing us that time exists.

Time is our way of identifying that one thing happens after another.but

How can one thing happen after another if time isn't real?

 

[Nakosis]

How can one thing happen after another if time isn't real?

Because change is real. Time is just a way of quantifying change.

I suppose the disagreement being that time exists as a separate force that acts on reality vs change which is all forces acting concurrently on reality.

Time we usually just identify a cyclic event that has a consistent interval, like the rotation of the earth to identify, categorize some other event. As @ChristineM said, it provides a method/tool to measure the gap between events.

 

[ChristineM]

How can one thing happen after another if time isn't real?

Time is a function of relativity and only appears to exist from the observer's point of view.

It has not be defined, there is no time particle. Its measurement is illusory and varies from person to person, their speed and position.

However the arrow of time is a concept to describe in the one way nature of entropy, entropy manifests itself in change.

 

[exchemist]

Albert is quoted to say.....

Time is an illusion

I think that may be a misquotation.

What I think he said was that the distinction between past, present and future is a stubbornly persistent illusion.

That is very different.

I can't imagine Einstein saying time itself is an illusion, since most of his equations include time (or velocity or acceleration, both of which have to presuppose time in order to mean anything.).

 

[Yerda]

Because change is real. Time is just a way of quantifying change.

I suppose the disagreement being that time exists as a separate force that acts on reality vs change which is all forces acting concurrently on reality.

Time we usually just identify a cyclic event that has a consistent interval, like the rotation of the earth to identify, categorize some other event. As @ChristineM said, it provides a method/tool to measure the gap between events.

Aye, but what I'm getting at is that for there to be change, time must be 'real'. No time = no change. Agreed?

Time is a function of relativity and only appears to exist from the observer's point of view.

It has not be defined, there is no time particle. Its measurement is illusory and varies from person to person, their speed and position.

However the arrow of time is a concept to describe in the one way nature of entropy, entropy manifests itself in change.

Our measurement of length also varies from one frame of reference to another. We would agree that length (i.e. space) is real I'm sure. So why not time?

We'd still be in the position of saying one thing happened after another, even if we disagree on which was first. To even have the disagreement we'd have to agree that time is a measurable quantity. No?

 

[ChristineM]

Aye, but what I'm getting at is that for there to be change, time must be 'real'. No time = no change. Agreed?

Our measurement of length also varies from one frame of reference to another. We would agree that length (i.e. space) is real I'm sure. So why not time?

We'd still be in the position of saying one thing happened after another, even if we disagree on which was first. To even have the disagreement we'd have to agree that time is a measurable quantity. No?

Lets talk quantum, the universe is comprised of quantum stuff, every experiment ever carried out on the quantum realm has proved positive, it may be mind blowing but it is precisely how the universe works. In quantum equations there is no time.

Time is an imaginary quality a mathematical reality that has no meaning or substance outside the mind, a method to measure the passing of entropy.

 

[Yerda]

Lets talk quantum, the universe is comprised of quantum stuff, every experiment ever carried out on the quantum realm has proved positive, it may be mind blowing but it is precisely how the universe works. In quantum equations there is no time.

Time is an imaginary quality a mathematical reality that has no meaning or substance outside the mind, a method to measure the passing of entropy.

The equations of quantum mechanics, quantum field theory etc are generally time dependent to the best of my knowledge. See:

Schrödinger equation - Wikipedia

I think we might be caught up in what 'real' means here. Time is a measurable quantity in every theory or model I've ever seen but whether that makes it 'real' I'm not too sure. I don't know if it's a feature of the observer-independent universe, but I don't know what is. I am sure that to talk of change of any kind we need to talk of time and I guess that makes it real enough for me.

Also, physics is bonkers.

 

[Thief]

I think that may be a misquotation.

What I think he said was that the distinction between past, present and future is a stubbornly persistent illusion.

That is very different.

I can't imagine Einstein saying time itself is an illusion, since most of his equations include time (or velocity or acceleration, both of which have to presuppose time in order to mean anything.).

the means of measure is man made
and exists only in your head

in his famous equation ....he needed a Constant as a reference
but the speed of light....believed to be constant
is measured
a unit of distance compared to a unit of movement
meters to seconds

both units are man made
and neither are force or substance

 

[blü 2]

Does spacetime exist as a physical reality?
Or is spacetime accepted as a reality because of its ability to accurately predict physical reality?

If spacetime is a physical reality, does this mean the past and future exist concurrently with now as physically realities?

As I understand it, no.

There is no scientific definition of NOW that I'm aware of, the observer's own subjective present instant. Yet it's the only temporal instant you'll ever occupy. Your past doesn't exist, only the memories of it that you have NOW, and your future doesn't exist, and isn't subject to memory anyway.

The future does not exist for any one observer. She may observe that her twin brother back on earth is aging faster than she is as she accelerates towards Alpha Centaurus ─ is experiencing more time ─ but when she comes back, physiologically years younger than he is, neither of them will have been into their own future.

(When I saw this article in Science Daily, it occurred to me that it arguably implies NOW is not a point, but a smear one ten-billionth of a second thick. If you thought NOW was a point in time, you might regard the extra thickness as a present ...)

 

[exchemist]

the means of measure is man made
and exists only in your head

in his famous equation ....he needed a Constant as a reference
but the speed of light....believed to be constant
is measured
a unit of distance compared to a unit of movement
meters to seconds

both units are man made
and neither are force or substance

Is distance is an illusion? After all, the means of measure are man-made.

Time is just the same.