# Is time infinite?

1. Aug 11, 2014

Entropy gave us that everything can happen, just that the chances of it happening is very slim. If time is infinite, wouldn't everything that can happen will happen?

2. Aug 12, 2014

### Simon Bridge

No, you are not accounting for conditional probability: some things happening may rule out other events from happening.

ifaik the current thinking on time is that it is finite in the past.
What happens in the future is up for grabs.

3. Aug 12, 2014

Do physicist believe that time in the future exist? I don't want to say "have already existed" or have "occurred". But it's in the same context. Do future exist even before we have experienced it?

4. Aug 12, 2014

### A.T.

Why don't you just wait and see?

5. Aug 12, 2014

### .Scott

I think you're getting twisted on semantics.
Here's the main point: Is there a way of determining whether or not the future exists before we get there? Can you describe an experiment - even a thought experiment - where the result would be different depending on whether the future preexisted? If you can, then scientific method can be applied to it. If not, then it is not part of science - it may be philosophy or it may be semantics. In this case, I suspect semantics.

Certainly scientific method presumes a universe that has some constant rules through out space and time. When Kepler described the orbits of the planets it was in anticipation that investigations that followed his would discover that those rules remained in effect. Similarly, we presume that those same rules were in effect well before Kepler.

6. Aug 12, 2014

### .Scott

Assuming that the mass and volume of the universe remained finite, then all possible states that could happen would happen. Once that situation occurred, there would be no other possibility than for the state of the universe to precisely match a state that had occurred in the past - causing the past to pick up from that point.

But - that's assuming that there is a finite limit to the mass and volume.

The notion that a finite mass and volume can be support only a finite set of states is asserted by the "Bekenstein Bound".

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

7. Aug 12, 2014

### Simon Bridge

There is no future without time - that is what "the future" is ... more time.
It is tricky to talk about a beginning or end to time since time is what things begin and end in.
Put another way: time is stuff happening in some order.

You mean "do future events exist before they are experienced?"??

That actually comes up in the context of space-time diagrams and general relativity ... it goes to the issue of free will vs destiny also covered by philosophy courses. We can mark in future events in space-time diagrams so that makes it look like destiny. However, it is important to understand that those are just marks on a bit of paper.

The standard position is that human decision-making (free will) makes sense, but it has to operate within the laws of physics. You cannot decide not to obey the law of gravity, but you can decide not to step off the high place. If you do step off that high place, your fall is not "predestined" in the sense of The appointment in Samarra.

Generally: future events are not predestined, but some events are more likely than others.

Note: we don't do philosophy here. Take care with questions like this.