Is our Universe 13.7 billion years old ? I'm not quite convinced

[Dave In Vermont]

If the Universe is 13.8 billion-years old, how long is that in Whiskey-Hours?

I'll phone Mr. Oliver R. Smoot -

Dave

[DRT]

1 hour ago, Herzy said:

Infinity can have boundaries ... right? 

No, they can't. An infinity has no boundaries.

[SilverAstro]

Oh gosh, we have created a looping or re-entrant topic, we did infinities somewhere here, back a bit ! It feels like an infinite time ago   hang on , ,

,,, yep page 1 ! It might even be a Mobius loop and we may never get out of it !!

Back then I mentioned George Cantor who did some interesting stuff on various sizes of infinity, countable and otherwise sets and stuff. Another good read, to bend one's mind, is Hilbert's Hotel with an infinite number of rooms and guests.

 

[Pippy]

is time not relative ?  .. along with everthing else ?

are we right to be laying down absolutes onto something we have not the foggiest idea what this place really is or how it could ever really exist in the first place etc etc ?

The wall flies must be giggling themselves silly watching us racking our little neurons like this

[andrew s]

6 hours ago, cloudsweeper said:

As I see it, infinities are infinite - no boundaries.  But you are right in saying that some are bigger than others - in fact, there is an infinite number of infinities!

Doug.

Yes as Doug says there are an infinity of mathematical infinities. They are tricky things and thinking about them helped send Cantor mad. This article ( https://en.wikipedia.org/wiki/Shape_of_the_universe ) gives a good overview of what we currently know/believe about the shape of the universe. It gives a clear idea about what me mean by an infinite universe in terms of a boundless metric. Note boundless is not the same as a boundary. 

In mathematics ( I do hope I get this the right way round) the real interval (0 1) without the end points 0 and 1 is boundless with the end points i.e. [0,1] it is bounded and has a boundary. To confuse things a finite universe may or may not have a boundary depending on its topography.

Regards Andrew

[Stub Mandrel]

7 hours ago, cloudsweeper said:

As I see it, infinities are infinite - no boundaries.  But you are right in saying that some are bigger than others - in fact, there is an infinite number of infinities!

Doug.

Yes, there are :-)

[DRT]

Just to check that my non-mathematician brain is following this correctly:

1. An infinite universe is boundless, and also has no boundaries. (I admit to not understanding why these are different)

2. A finite universe might or might not have a boundary. (Pass the Talisker - it might help me with this one!)

Is that correct? ("correct" having the meaning of "current generally accepted understanding")

[cloudsweeper]

1 hour ago, andrew s said:

Yes as Doug says there are an infinity of mathematical infinities. They are tricky things and thinking about them helped send Cantor mad. This article ( https://en.wikipedia.org/wiki/Shape_of_the_universe ) gives a good overview of what we currently know/believe about the shape of the universe. It gives a clear idea about what me mean by an infinite universe in terms of a boundless metric. Note boundless is not the same as a boundary. 

In mathematics ( I do hope I get this the right way round) the real interval (0 1) without the end points 0 and 1 is boundless with the end points i.e. [0,1] it is bounded and has a boundary. To confuse things a finite universe may or may not have a boundary depending on its topography.

Regards Andrew

Poor old Cantor, I can see how he went over the edge!  The one that really "gets" me is the infinitude of primes.  Think of a prime number of say half a million digits - that would be roughly a mile long if written down - and you can't divide anything into it!  Then write one down that would stretch to the Moon - same thing!  Intuition tells us that the bigger these numbers get, the less chance there is of there being another one, but there always is!  Aaaarrgh!

Doug.

[andrew s]

3 minutes ago, DRT said:

Just to check that my non-mathematician brain is following this correctly:

1. An infinite universe is boundless, and also has no boundaries. (I admit to not understanding why these are different)

2. A finite universe might or might not have a boundary. (Pass the Talisker - it might help me with this one!)

Is that correct? ("correct" having the meaning of "current generally accepted understanding")

Yes.

To help clarify things. If there is a boundary you can't go past it. For example, if you are inside a football its surface forms the boundary. However, if you can only be on its surface then it has no boundary.

So you can't get past a boundary. Boundless means that for any distance from you to any point in a space say R away there will always be a point P in the space further away i.e. Rp > R.

As an example, taking the open real interval (0,1) if you are at point just inside 0 then you can pick any point you like close to 0.999 but you can always find a point further away from you by adding a suitably small fraction to it, say point 0. 9999 then further away still 0.99999 etc ad infinitum. You can't pick 1 as it is not in the space.

[DRT]

6 minutes ago, andrew s said:

Yes.

To help clarify things. If there is a boundary you can't go past it. For example, if you are inside a football its surface forms the boundary. However, if you can only be on its surface then it has no boundary.

So you can't get past a boundary. Boundless means that for any distance from you to any point in a space say R away there will always be a point P in the space further away i.e. Rp > R.

As an example, taking the open real interval (0,1) if you are at point just inside 0 then you can pick any point you like close to 0.999 but you can always find a point further away from you by adding a suitably small fraction to it, say point 0. 9999 then further away still 0.99999 etc ad infinitum. You can't pick 1 as it is not in the space.

You had me at "Yes."

...now I need to go and lie down with a cold towel on my head while I contemplate a infinite universe that looks like a football

Thank you for the explanations.

I think the first point you make is very interesting. You see a boundary as something you cannot go beyond. I see a boundary as something that must have something else beyond it. Does the space beyond the boundary not count as being part of the universe, and if a finite universe is boundless is it not effectively infinite?

 

[andrew s]

13 minutes ago, DRT said:

Does the space beyond the boundary not count as being part of the universe

No, there is no outside. There are various multi universe theories etc. but the standard ( non pop) view is that there is nothing outside our universe accessible to science.

13 minutes ago, DRT said:

finite universe is boundless is it not effectively infinite

No, the surface of the football has no boundary but is quite finite so can be the universe. See the link I posted.

Regards Andrew

[DRT]

20 minutes ago, andrew s said:

No, there is no outside. There are various multi universe theories etc. but the standard ( non pop) view is that there is nothing outside our universe accessible to science.

No, the surface of the football has no boundary but is quite finite so can be the universe. See the link I posted.

Regards Andrew

I preferred it when you just said "Yes."

The first of those statements demonstrates a point I made earlier in this thread that our brains are incapable of truly understanding what infinity means without resorting to mathematics or related sciences. We appear to have created a situation where we can understand infinity by assigning our own rules and limitations that exclude the things we do not yet know. Just because something is not (yet) accessible to science does not mean it doesn't exist, it just means we cannot prove that it exists or accept that it exists without destroying the limitations of current understanding.

I really do need that Talisker now.

[Herzy]

1 hour ago, DRT said:

Just to check that my non-mathematician brain is following this correctly:

1. An infinite universe is boundless, and also has no boundaries. (I admit to not understanding why these are different)

2. A finite universe might or might not have a boundary. (Pass the Talisker - it might help me with this one!)

Is that correct? ("correct" having the meaning of "current generally accepted understanding")

You're thinking about this wrong. There is no boundary as in theres an "end" to the universe. The idea of smaller infinities just means that it can be infinite, but it can still shrink/expand. It is STILL infinity... just a smaller infinity. That is possible because infinities can be different sizes.

Our ape-brains simply can't fathom infinity because it is out of any of our experiences. You just need to think in analogies - like my numerical/spacial infinity one.

[Herzy]

4 minutes ago, DRT said:

I preferred it when you just said "Yes."

The first of those statements demonstrates a point I made earlier in this thread that our brains are incapable of truly understanding what infinity means without resorting to mathematics or related sciences. We appear to have created a situation where we can understand infinity by assigning our own rules and limitations that exclude the things we do not yet know. Just because something is not (yet) accessible to science does not mean it doesn't exist, it just means we cannot prove that it exists or accept that it exists without destroying the limitations of current understanding.

I really do need that Talisker now.

You are right that we fall back on mathematics to explain infinity because we don't understand it. The problem in what you said is assuming that mathematics isn't a reliable method of falling back on. Math works. It makes predictions and for many centuries has never failed. I believe that mathematics is humanities greatest invention. We literally found a language that describes the universe.

[andrew s]

3 minutes ago, Herzy said:

There is no boundary as in theres an "end" to the universe.

We don't know this. Possibly I don't understand what you mean by "an "end"".

 

4 minutes ago, Herzy said:

The idea of smaller infinities just means that it can be infinite, but it can still shrink/expand.

I have never come across this idea - shrinking/expanding infinities. Can you point me at a reference please.

Regards Andrew

PS Sorry about the constant flow of  posts but just had a foot operation and can't do much else at the moment!

[DRT]

18 minutes ago, Herzy said:

You're thinking about this wrong.

That is a very bold statement.

Andrew S answered "Yes" to exactly the same question. I will let Andrew take the argument forward.

[Herzy]

2 minutes ago, DRT said:

That is a very bold statement.

Andrew S answered "Yes" to exactly the same question. I will let Andrew take the argument forward.

That wasn't meant to be rude. I didn't do a great job explaining my first post so people took it the wrong way.

[DRT]

15 minutes ago, Herzy said:

You are right that we fall back on mathematics to explain infinity because we don't understand it. The problem in what you said is assuming that mathematics isn't a reliable method of falling back on. Math works. It makes predictions and for many centuries has never failed. I believe that mathematics is humanities greatest invention. We literally found a language that describes the universe.

At no point have I said that mathematics is unreliable, all I am saying is that our knowledge of the universe is still developing so the language we use to explain it has its limitations.

A more accurate statement would be that we have discovered a language that is helping us describe what we currently know about the universe.

[Herzy]

1 minute ago, DRT said:

At no point have I said that mathematics is unreliable, all I am saying is that our knowledge of the universe is still developing so the language we use to explain it has its limitations.

A more accurate statement would be that we have discovered a language that is helping us describe what we currently know about the universe.

Wouldn't it have to describe the universe if it can make predictions? Does math describe what we already know or can it make predictions that help us discover new things? I'm confused now.... :/

[Herzy]

25 minutes ago, andrew s said:

We don't know this. Possibly I don't understand what you mean by "an "end"".

 

I have never come across this idea - shrinking/expanding infinities. Can you point me at a reference please.

Regards Andrew

PS Sorry about the constant flow of  posts but just had a foot operation and can't do much else at the moment!

by "end" I meant "wall". Like an actual wall that you can't go past. Sorry, poor choice of words on my part.

The universe may be infinite, we only see a finite section of it due to the speed of light and it's limitations. So, for the moment, let's assume the universe is infinite. If it's infinite and it's expanding doesn't that mean that the infinity now is bigger then the infinity 100 years ago? 

As for the posts, me too. I've got nothing to do so i just post on here all day!

[DRT]

4 minutes ago, Herzy said:

Does math describe what we already know or can it make predictions that help us discover new things?

It does both, but that does not mean that the predictions are correct nor does it mean that we have predicted everything we need to in order to describe the universe. The picture is incomplete, so we must accept that neither our brains nor mathematics can currently comprehend or understand everything.

[Alien 13]

I think early calculators where smarter than us by just registering ERR when dividing 1 by 0, our brains cannot realy visualize infinity and struggle with zero too.

Alan

[DRT]

3 minutes ago, Alien 13 said:

our brains cannot realy visualize infinity and struggle with zero too

Aren't they the same thing?

 

[Alien 13]

2 minutes ago, DRT said:

Aren't they the same thing?

 

I wouldn't be surprised if they where in terms of the universe, both completely mad concepts.

Alan

[Herzy]

1 minute ago, Alien 13 said:

I wouldn't be surprised if they where in terms of the universe, both completely mad concepts.

Alan

That might be the next big revelation. That infinity and zero are somehow connected. 

Hmmmmmmmmm