# Question About Time: What Would Happen?

• Nightsky
In summary, the conversation revolved around the concept of time and its relation to motion and change. Some participants discussed the idea that if time slowed down or stopped, we would not be able to perceive it due to our perception being based on motion and change. Others explored the idea of being able to travel into the future by sitting still in a "dead area" of the universe, but there was some debate over the validity of this concept. Overall, the discussion was centered around the complexities and mysteries of time and its relationship to the universe.
Nightsky
I don't have a mathematical background (Am acctually still in gr.10 in high school) but the universe has always interested me. I was thinking recently about time. If time slowed down, we would not be able to tell. Since everything would slow down in our mind.. We could not tell. What if time stopped. What do you figure would happen at that point.

By the way, I am new here. Hello everyone :-) I will maybe pop a math question into the math homework section sometime as well.

It is supossed that the time slowing keeps the same into your brain (if not you die in the process) if you agree that the laws of physics are the same independent of the system of reference. So you wouldn't experience it. If time stops in all frames of reference, there will be not universe (there would not be physical process),nor observers, if you are talking about one universe. (alhotugh the bad it seems like idea) that's the point to start with the idea developed from some people that there is not a point of "starting" of time.

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Because you say "the universe has always interested me" I will add that what you said about time applies to space also. If everything in space is expanding, it is impossible to tell.

Well, the universe is expanding, but the reason we can tell is that objects (like us) are not expanding with it.

If time stops everywhere and starts again there will be no evidence that it stopped in the first place. When time stops so will all thought processes and all motions. But personally I'm not a big fan of time because it's trying to kill me.

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Nightsky said:
If time slowed down, we would not be able to tell. Since everything would slow down in our mind.. We could not tell. What if time stopped. What do you figure would happen at that point.

You notice timeflow by motion and change. Motion is expressed as $$\Delta x/\Delta t$$ so in fact the actual timespeed is irrelevant for the calculation of motion as long as for every $$\Delta x$$ there is a matching $$\Delta t$$.
This remains valid even for $$\lim_{\Delta x, \Delta t \to 0}\frac{\Delta x}{\Delta t}$$ (you end up with 0/0 but this can be solved using l'Hopital's rules). So even if time stopped, we would not notice it.

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Mortimer said:
You notice timeflow by motion and change. Motion is expressed as $$\Delta x/\Delta t$$ so in fact the actual timespeed is irrelevant for the calculation of motion as long as for every $$\Delta x$$ there is a matching $$\Delta t$$.
This remains valid even for $$\lim_{\Delta x, \Delta t \to 0}\frac{\Delta x}{\Delta t}$$ (you end up with 0/0 but this can be solved using l'Hopital's rules). So even if time stopped, we would not notice it.

It does NOT remain true in the limit. Limit of quotients is NOT the quotient of limits. This is the whole point of the limit concept and epsilontics.

ok

Well I know that time slows down as we approach the speed of light. The universe had supposedly started as a singularity (this is the theory anyway) And our galaxy alone is quite a few LY in diameter. I am wondering if anyone knows how fast the Earth is moving (Not just in orbit around the sun) this would include the rate at which our galaxy is moving. I would immagine we are moving near the speed of light due to the rapid expansion of the universe.

Is it possible that if you sat perfectly still in a dead area in the universe not under any influence of gravity or speed. And than came back to earth, would you... be in the future? Or just you and the atoms in your body would have aged faster? Roar its so confusing, yet so interesting :(

Rebel said:
Sorry, i didnt know that quotient of two limits is NOT the limit of quotients. Can you enlightme? i mean, where can i find this?

Any serious textbook of calculus aimed at math students instead of engineers should have a discussion of the issues. Until the 19th century the idea that you got a derivative by dividing "little nothings" was common, and much derided by philosophers like Berkley. Then gradually the problem was understood and brought under control. In spite of the notaion, dy/dx is not a quotient, it is the limit of quotients whose numerators and denominations are finite numbers, not zero. Weierstrasse intorduced his epsilons and deltas in order to make these ideas rigorous.

Nightsky said:
Is it possible that if you sat perfectly still in a dead area in the universe not under any influence of gravity or speed. And than came back to earth, would you... be in the future? Or just you and the atoms in your body would have aged faster? Roar its so confusing, yet so interesting :(

There are two ways to answer this: 1) There is no such thing as "sitting still". 2) You are always "sitting still". The second is really the most accurate way to say it. According to the general principle of relativity, "All Gaussian co-ordinate systems are essentially equivalent for the formulation of the general laws of nature" (Einstein, Relativity: The Special and General Theory, 108). Basically, what this means is that in order to say how "fast" you're moving, you have to pick something in the universe and say, "That's standing still." Then using this place you call "still" you can then state your velocity. Another approach would be to just claim that you are standing still, then you can base all velocities on your frame of reference.

However, as to the expansion of the universe, refer here: https://www.physicsforums.com/showthread.php?t=74478

## 1. What is the concept of time?

The concept of time is a fundamental aspect of the universe that measures the duration of events and the intervals between them. It is often described as the fourth dimension, alongside the three dimensions of space.

## 2. Can time be manipulated or controlled?

According to current scientific understanding, time cannot be manipulated or controlled. However, there are theories that suggest time travel may be possible in the future through advanced technology or through the bending of spacetime.

## 3. Does time always move forward?

Time is generally believed to move in a linear direction from the past to the present to the future. However, some theories, such as the concept of eternalism, propose that time may exist all at once and our perception of it moving forward is simply an illusion.

## 4. What would happen if time stopped?

If time were to stop, the universe as we know it would cease to function. All processes and events would freeze, and no new events could occur. This scenario is purely hypothetical and is not currently supported by any scientific evidence.

## 5. How does time relate to space?

Time and space are interconnected and make up the fabric of the universe known as spacetime. Einstein's theory of relativity states that the curvature of spacetime is affected by the presence of mass and energy, and this curvature affects the flow of time.

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