# Time

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1 minute ago, Strange said:

Not sure what you mean. They are just measurements. If you measure the length of your dining table, is it a “snapshot”?

Date time stamp of a location in space with xyz coordinates. So just one instance.

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5 hours ago, Theredbarron said:

I noticed you dont answer my questions at all like this one.

Perhaps more to the point, you just don't like the answers you are getting. Time is certainly a dimension...We calculate a position in space with length, breadth and height co-ordinates, but due to the finite speed of light, we also need a time co-ordinate...hence the defined spacetime.

Or are you asking a more in depth question re is time real? That question is more philosophical at this time [no pun intended] and is debatable. Perhaps the question that should be asked is, is time fundamental? Here is an interesting discussion re time by Sean Carroll...https://www.youtube.com/watch?v=FVINOl0Ctfk

Or are you asking or suggesting is time travel possible? If so, the answer is yes, at least into the future. The astronauts on the ISS for example when returning to Earth, will have aged slower then us mortals they have left behind, although the effect and amount is insignificant. One would need to travel at some relativistic velocity to have a real measurable effect of time travel. Time travel into the past is another kettle of fish and mostly deemed as impossible as one would need to exceed the speed of light. In essence, time travel is allowed by GR but the limitations of our technology at this time, makes it still just science fiction. https://www.space.com/27970-whats-new-black-holes-kip-thorne.html

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4 minutes ago, Theredbarron said:

Date time stamp of a location in space with xyz coordinates. So just one instance.

Maybe. If you make a set of measurements they are not guaranteed not to change so you can think of that as a snapshot.

But the way you phrase it makes it seem like you are thinking of the time dimension as completely separate from the others. This is not the case; we know they are all inextricably linked. So it is a genuinely 4 dimensional measurement system not just a 3 dimensional one with time added on

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8 minutes ago, beecee said:

Perhaps more to the point, you just don't like the answers you are getting. Time is certainly a dimension...We calculate a position in space with length, breadth and height co-ordinates, but due to the finite speed of light, we also need a time co-ordinate...hence the defined spacetime.

Or are you asking a more in depth question re is time real? That question is more philosophical at this time [no pun intended] and is debatable. Perhaps the question that should be asked is, is time fundamental? Here is an interesting discussion re time by Sean Carroll...https://www.youtube.com/watch?v=FVINOl0Ctfk

Or are you asking or suggesting is time travel possible? If so, the answer is yes, at least into the future. The astronauts on the ISS for example when returning to Earth, will have aged slower then us mortals they have left behind, although the effect and amount is insignificant. One would need to travel at some relativistic velocity to have a real measurable effect of time travel. Time travel into the past is another kettle of fish and mostly deemed as impossible as one would need to exceed the speed of light. In essence, time travel is allowed by GR but the limitations of our technology at this time, makes it still just science fiction. https://www.space.com/27970-whats-new-black-holes-kip-thorne.html

I am definitely thinking about time travel. I was thinking that instead of going to the time, bringing it here without the aging. I actually thought that maybe there is more then 4 dimensions its just which one is relative?

6 minutes ago, Strange said:

Maybe. If you make a set of measurements they are not guaranteed not to change so you can think of that as a snapshot.

But the way you phrase it makes it seem like you are thinking of the time dimension as completely separate from the others. This is not the case; we know they are all inextricably linked. So it is a genuinely 4 dimensional measurement system not just a 3 dimensional one with time added on

I am picking up what your saying. I just try to ask all the question rather then judge the question with an assumption from my point of view.

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2 minutes ago, Theredbarron said:

I actually thought that maybe there is more then 4 dimensions its just which one is relative?

We are pretty sure there are only 3 space dimensions and 1 time: https://en.wikipedia.org/wiki/Spacetime#Privileged_character_of_3+1_spacetime

(And they are all relative)

3 minutes ago, Theredbarron said:

To take a simple example, if you are standing on a railway station and a train is moving past you then distances on the train (in the direction of travel) will be shorter but times will be longer. You can think of this as "swapping" a portion of the space dimension for the time dimension. (More accurately, it is a rotation from space to time.)

So you can't think of the universe as having a fixed 3D spatial structure and time that ticks along unchangingly. That (perhaps surprisingly) isn't how the universe works.

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19 minutes ago, Theredbarron said:

I am definitely thinking about time travel. I was thinking that instead of going to the time, bringing it here without the aging. I actually thought that maybe there is more then 4 dimensions its just which one is relative?

Bringing the future here? We are all progressing through time at one second per second in our own frame of reference....even anyone who was/could be moving at a speed close to "c". It is only when we observe the other frame of reference that we will notice their time progressing at a different rate to ours. This time dilation/length contraction effect has been observed. A real theoretical practical example would go like this......If you and I were exactly the same age, and  I being the more intrepid, left on a relativistic space ship travelling at 99.999% "c" and turned around after 6 months and returned to Earth another 6 months later, all my on board mechanical and biological clocks would tell me that 12 months have passed for me on board. I open the ships door upon landing and I will have found my self around 223 years in the future ahead of my ship's clock and my own biological time, with you long dead and buried.

On the extra dimensions, we have absolutely no indication of any.

23 minutes ago, Theredbarron said:

I am picking up what your saying. I just try to ask all the question rather then judge the question with an assumption from my point of view.

That's good, and a view you should hold all the time.

As Strange just said here.....

18 minutes ago, Strange said:

So you can't think of the universe as having a fixed 3D spatial structure and time that ticks along unchangingly. That (perhaps surprisingly) isn't how the universe works.

is what Einstein's SR is all about......that is, the speed of light in a vacuum is a constant "c" and that therefor it is space and time that are actually personal and variable components dependent on our speed and position in a gravity well.

Edited by beecee

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Can you be in the future and the present at the same time?

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1 minute ago, Theredbarron said:

Can you be in the future and the present at the same time?

You are always in your present...even with my example above, when you land 223 years ahead of your ship's clocks, it becomes your present. You will never be able to return to the day you left Earth.

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1 minute ago, beecee said:

You are always in your present...even with my example above, when you land 223 years ahead of your ship's clocks, it becomes your present. You will never be able to return to the day you left Earth.

Ok so what I was meaning by bringing the future here is because we cant be there and here. What I was meaning is by prediction we can determine certain things and make certain things happen earlier then predicted. For example food rationing. Changing how much something is happening to change when something is going to happen. You ration so you can have food for longer time. Evolutionary patterns of relative events of all types is what would be used to compare what is to happen. Changing the existence rather then the time itself. I dont know if that makes any sense.  I guess it would be more of a perception of time since we can really go there yet, why not make it come here?

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1 hour ago, Theredbarron said:

Can you be in the future and the present at the same time?

Present and future are not well-defined terms in physics. We like to quantify things, and the measurements involved depend on your frame of reference. One person's future could be in another person's past.

Basically, your question is ambiguous. It is not asked in a way that anyone can give a definitive answer.

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