# Duration of the universe

1. Sep 25, 2014

### Unnickporser

What is the duration of universe?

2. Sep 25, 2014

### Staff: Mentor

Welcome to the PF.

Could you please clarify your question? By '"duration" do you mean how old the universe is now? If so, that is easy to find with Google or Wikipedia.

Or do you mean what would be the total lifetime of the universe? If you mean total lifetime, are you familiar with the difference between "open" and "closed" models of the universe?

3. Sep 25, 2014

### TheScienceOrca

I think this is a spin of my thread just post on it, it already has a reply from a reputable member which I will be soon to comment on.

4. Sep 26, 2014

### Unnickporser

Well, I refered to duration like I said, to lifetime, not time from big bang. Anyway, in Wikipedia there is only diverse stimation from different models, but not a really response to the question anyway

5. Sep 26, 2014

### Chronos

There are different ways to answer the question. The conventional view is the universe arose ~13.7 billion years ago in what is called the Big Bang. It is, however, unclear if time itself originated with the Big Bang, or, the BB was preceded by some yet unknown precursor state or states. Some have even suggested the universe is stuck in a time loop that endlessly repeats [e.g., bouncing cosmologies]. In that sense it could be said the age of the 'universe' [in the sense of all that is or ever was] is undefinable.

Last edited: Sep 26, 2014
6. Sep 27, 2014

### Staff: Mentor

If you don't mean lifetime, then what do you mean?

7. Sep 27, 2014

### TheScienceOrca

I will translate his comment;

"Well, I refered to duration like I said, to lifetime, not time from big bang. Anyway, in Wikipedia there is only diverse stimation from different models, but not a really response to the question anyway"

Means: How long will the universe exist for not how long it as has existed.

Analysis: He wants to know how long the universe will exist for.

Answer: There are many "end of the universe" theories such as a deep freeze. Or string field theory which has bubbles merging and splitting I guess.

They are all theory but are fun to take a look at.

8. Dec 1, 2014

### Garrulo

But this is a neccesary knowing because finite real statistics used in physics and all of sciences need to know how many times a random phenomemon will ocurr. There are people seeking through planck units, but , I would like to know it too. What is the duration (from the start to the end), not the actual age of universe? And its dimensions?

9. Dec 1, 2014

### Staff: Mentor

10. Dec 1, 2014

### Garrulo

I don´t understand you , sorry, my english no good. Could you tell it about other words

11. Dec 1, 2014

### Staff: Mentor

I said, I do not understand your question. Are you asking how big the universe is and how long it will exist?

12. Dec 1, 2014

### Garrulo

Yes, this is my question

13. Dec 1, 2014

### phinds

Neither the size nor the expected life span of the universe is known.

The size may be infinite or it may be finite but bounded. If it is finite, the size is not known.

There is currently no reason to believe that the lifetime of the universe will be infinite, but in any case, it will certainly last for many orders of magnitude longer than it has so far.

14. Dec 1, 2014

### Staff: Mentor

We don't know how big the universe is. We also do not know how long it will exist for.

15. Dec 1, 2014

### phinds

Garrulo, as you can see, here on the Physics Forum, some of us like to repeat answers that have already been given. ;)

16. Dec 2, 2014

### Garrulo

It is said that actual quantum theories can´t measure times longer than 1018 s, and this is the reason because we measure this quantity for the universe age

17. Dec 2, 2014

### Garrulo

Mi question is not trivial. We use probability all times, but probabilities small are not possible in function of the number of experiments that can be done in the universe about the experiment we wish know if a determinate event can ocurr. For example, age of universe is around 1018 s, and universe radius is around 1018 m. An event of an experiment done in a meter length laboratory with duration of one second have a probability of 10-36 can be discharged

18. Dec 2, 2014

### phinds

HUH? Where did you hear this? Sounds like nonsense to me. Can you give me a citation?

19. Dec 2, 2014

### phinds

I can't make any sense at all out of this post. Can you say it differently?

20. Dec 3, 2014

### William Donald

We do not know the duration of a typical universes lifetime, because the only universe we can observe is our own, and we can't even observe all of it. Our universe right now is to be an estimated 13.8 billion years old; however, that could be only a small chunk of how long they survive for. It could also be long overdue for an end or retraction.

Maybe one day we will come close to an answer, but for now; we have to rely on what we can observe and learn. From there we will gain insight.