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

[cloudsweeper]

@Herzy - that's an easy one. 1 (or anything, really) divided by zero is infinity.

Doug.

[DRT]

45 minutes ago, Herzy said:

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

Hmmmmmmmmm

Excellent.

Presumably Alan and I should be dusting off our bow ties and dinner suits sometime soon to go pick up our Nobel Prize for this great discovery?

 

[andrew s]

1 hour ago, Herzy said:

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

Yes it can and does. That is exactly what our (mathematical) models in Physics do. They do need grounding in measurement thought.

 

1 hour ago, Herzy said:

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? 

I see what you mean. The sense in which the universe is infinite means you can always find a point further away than any you specify. This is always true with or without expansion. I GR it is referred to as a metrical expansion but I don't have a good grasp on what that means about a bigger infinity or not. I will do some research.

Regards Andrew

Edit

PS Eating tea has jogged the mind. If you take the first Cantor infinity - the number of points on the real line. Then the number of points on the line is independent of the length of the line. The number of points in a real plane is the square of the number of points on a real line and so on to a cube and hyper-cubes.

In this sense the size of the infinity of the universe (if it is infinite) does not increase with the metrical expansion.

[ollypenrice]

12 hours ago, DRT said:

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

Hmmm. The surface of a sphere has no boundaries but it has a finite area. It is in that sense finite but unbounded. DOn't hit me, I'm only quoting my Cosmology text book...

lly

[DRT]

8 minutes ago, ollypenrice said:

Hmmm. The surface of a sphere has no boundaries but it has a finite area. It is in that sense finite but unbounded. DOn't hit me, I'm only quoting my Cosmology text book...

lly

No need to duck, Olly. I said an infinity has no boundaries.

Finite stuff is a whole different ballgame

 

[Herzy]

1 hour ago, DRT said:

No need to duck, Olly. I said an infinity has no boundaries.

Finite stuff is a whole different ballgame

 

Okay I will try to just restart the conversation. I didn't explain what I was trying to say very well.

Infinity has no boundaries, you are right.

However, 100 has more numbers then 2.

The amount of numbers you could write between 0-2 is infinite.

The amount of numbers between 0-100 is also infinite.

So they are both infinite, yet one is bigger then the other? I wouldn't describe that as a boundary because it's still infinite. One is just bigger then the other. It's very confusing because if you think about it they are the same amount of numbers - infinity. But at the same time 2 and 100 don't have the same amount of numbers... Let me know what you think because this is getting complicated and I'm having trouble understanding the idea of a finite set of numbers that can be divided into an infinite amount of pieces.

[DRT]

I understand that.

The point I was trying to make is that our methods of describing infinities mathematically seem to be based on assigning limits (in the above case 0 and 2 or 0 and 100) within which the infinity exists. That is the bit that demonstrates both the limitation of mathematics and the limitation of our brains. Infinity has no limits, but our only way of comprehending an infinity seems to be by giving it limitations and then pretending they don't exist.

[IanL]

For anyone struggling with infinities, I'd suggest getting a copy of "Things to Make and Do in the Fourth Dimension" by Matt Parker. (https://www.amazon.co.uk/Things-Make-Do-Fourth-Dimension-ebook/dp/B00O2LM3LW/ref=sr_1_1?s=books&ie=UTF8&qid=1472976776&sr=1-1&keywords=things+to+make+and+do+in+the+fourth+dimension).

It's an entertaining and not too taxing read on a whole variety of mathematical ideas, and has a great chapter on infinities and why some are bigger than others.  The upshot is that an infinity is not a number of things, it is a set of things (in the formal mathematical definition of "set").

The whole book gave me a much better understanding of the fundamental basis of mathematics, but the key point is that you set out a series of axioms (things that you define as being fundamentally true and requiring no proof), and then build on them using logic.  You just have to accept wherever that logic takes you, regardless of whether it runs counter to your "common sense".

Other things I learned include the fact that you can't tie knots in a universe with more than three free spatial dimensions (basically the extra dimensions allow the string to slip around the back and so there is no knot).  This turns out to be really important, as the mathematics of knots and that of protein folding are the same.  Protein folding is fundamental to a lot of complex chemistry and life itself, and it may well be that we exist in a three dimensional universe simply because of this fact.

Anyway, give it a read, highly recommended.

[cloudsweeper]

The infinity of divisions between say 0 and 1 does have boundaries, but the infinity of integers (positive and negative) does not.

Doug.

[DRT]

5 minutes ago, cloudsweeper said:

The infinity of divisions between say 0 and 1 does have boundaries, but the infinity of integers (positive and negative) does not.

Doug.

I like that. The "between x and y" thing bothers me.

[cloudsweeper]

Just now, DRT said:

I like that. The "between x and y" thing bothers me.

Elaborate, please Derek!

[Herzy]

8 minutes ago, cloudsweeper said:

The infinity of divisions between say 0 and 1 does have boundaries, but the infinity of integers (positive and negative) does not.

Doug.

How would that not be infinite? You can always divide the number by 2.

[andrew s]

Hi, my we have been busy. 

Just a few points I would like to clarify as I understand them.

Firstly division by zero (in modern mathematics) is not an allowed operation i.e. does not produce a number. 

An interval of real numbers is unbounded if you exclude the end point and bounded if you included them. As I tried to explain before bounded means you can go no further. So the bounded interval [0.1] has points 0 and 1 which you can't go beyond. However, for the open interval (0,1) you can pick any number you like (between 0 and 1 but not including 0 or 1) and I can write down numbers that will be closer to 0 or 1 than yours and so on. Try it its fun to do - honest.

The concept of the magnitude of a number (or interval) is well defined etc. but not the same or simply related to infinity of points on a line. 20>0  -1000< 10 but mod(-1000) >mod(10) etc.

We can a do take limits as say x -> infinity by which we mean take x as arbitrarily large a number you wish to have. However, than is not related to how many points are there on a real line (closed or open). In this case any intervals  0,1 or 0,100 or -1000, 3000 have the same number of points on them and the same infinity.

The limit 1/x as x-> infinity is 0 and is an allowed in modern maths.

Not sure this will help but more fun for a Sunday morning.

Regards Andrew

[DRT]

16 minutes ago, cloudsweeper said:

Elaborate, please Derek!

It is relatively easy to comprehend an infinity of integers as most people are able to grasp the fact that there is no way of reaching an upper or lower limit where one would have to stop adding or subtracting 1. An infinity of integers therefore (to me) seems to be a relatively simple and intuitive way of describing the concept whether it be an infinite number of things or an infinite space.

The "between x and y" thing is counter intuitive and therefore difficult to understand as it is trying to describe a space that has no limits by placing limits around it. Whilst that might work for mathematicians in their endeavors to do things with one or more infinities it does not mean much to a non-mathematician who might be trying to imagine what a real life infinity looks or feels like.

 

[Pippy]

The bit that bothers me is that we're trying to convince ourselves that we know what 'infinity' actually means.

[DRT]

2 minutes ago, Pippy said:

The bit that bothers me is that we're trying to convince ourselves that we know what 'infinity' actually means.

I'm not

I am trying to explain that our brains can't know what an infinity actually means (because our brains are physically incapable of doing so) and therefore we need relatively simple and intuitive means of allowing us to have a even a basic understanding of what an infinity might be.

[DRT]

For the record, I think the answer to the question in the title of this thread is no. I have yet to see any convincing argument that time had a beginning, therefore the universe is of infinite age.

[andrew s]

24 minutes ago, DRT said:

The "between x and y" thing is counter intuitive and therefore difficult to understand

 

22 minutes ago, Pippy said:

he bit that bothers me is that we're trying to convince ourselves that we know what 'infinity'.

Ok sorry to be counter intuitive. The reason I did the x an y thing was to try to differentiate the differences between having and not having a boundary and being finite and infinite. Your list of integers going of to infinity is intuitive. If I can just have an x (no y) the the positive intergers has a lower bound at 1 (or 0 if you prefer) but no upper bound.

Pippy, I think we are discussing different ideas about infinity - I was concenrating of the man made mathematical concept. I suspect you are thinking more of the harmony of the  spheres.

Regards Andrew

[andrew s]

5 minutes ago, DRT said:

For the record, I think the answer to the question in the title of this thread is no. I have yet to see any convincing argument that time had a beginning, therefore the universe is of infinite age.

What would you take a evidence of a beginning as the whole of modern cosmology points to a beginning and has a raft of data to support it? Just one small example is that if you extrapolate the expansion of the universe back it time you get to a stating point

Regards Andrew

[Pippy]

Nooo don't worry, I wasn't refering to any particular message in this thread (or on this forum even). My bad Andrew.

I have a habbit of deliberately trying to throw the odd spanner in the works just to try and keep the listeners thinking about things rather than just simply 'accepting' what we're led to believe might be the case (in general) as it were.

 

[DRT]

2 minutes ago, andrew s said:

What would you take a evidence of a beginning as the whole of modern cosmology points to a beginning and has a raft of data to support it? Just one small example is that if you extrapolate the expansion of the universe back it time you get to a stating point

Regards Andrew

I accept that the era in which we currently live and the space that we and the stars around us occupy had a beginning at the point of the big bang. That is not the same as time having a beginning.

As @Alien 13 pointed out earlier in this thread we have as much difficulty comprehending nothingness as we do infinity. The idea that there was no period of time before the big bang just seems nonsensical to me.

 

 

[andrew s]

8 minutes ago, DRT said:

The idea that there was no period of time before the big bang just seems nonsensical to me.

That's fine by me you can hold what opinion you like but just to be clear the currently accepted model of cosmology does have a start point to space and time. It may well be wrong and you right - possibly time will tell.

Personally I have no difficulty considering infinity or nothingness but I see them just as other concepts that help us grasp our reality. I suspect all concepts are hard to pin down if you worry about them - what exactly is energy or entropy what of love or hate (added these for Pippy). My approach is not to worry too much about it.

Regards Andrew

[Pippy]

4 minutes ago, andrew s said:

Personally I have no difficulty considering infinity or nothingness but I see them just as other concepts that help us grasp our reality. I suspect all concepts are hard to pin down if you worry about them - what exactly is energy or entropy what of love or hate (added these for Pippy). My approach is not to worry too much about it.

lol, love and hate and the likes - an off-shoot of this universe for sure   I'm sure the majority of peeps (guys) on this forum dare not venture into such off-shoots

Anyway, I don't honestly think that anyone here is really worrying about anything that has been talked about, I tend to think most people have many questions through out their lives (out of pure interest if nothing else), which, if allowed to do so, and given the chance, they will ask.

I was often told not to ask questions in my earlier years of life, or at least not to ask so many of them

For all you parents out there - NEVER EVER tell any child to stop asking questions, no matter what they might be !

[DRT]

43 minutes ago, andrew s said:

That's fine by me you can hold what opinion you like but just to be clear the currently accepted model of cosmology does have a start point to space and time. It may well be wrong and you right - possibly time will tell.

Personally I have no difficulty considering infinity or nothingness but I see them just as other concepts that help us grasp our reality. I suspect all concepts are hard to pin down if you worry about them - what exactly is energy or entropy what of love or hate (added these for Pippy). My approach is not to worry too much about it.

Regards Andrew

No worrying going on here, Andrew.

I enjoy conversations like this when a common language can be found to make it relevant to everyone. That is my main motivation in trying to steer away from purely mathematical concepts so that non-mathematicians like myself can have a chance of grasping what is going on.

On the big bang and time question, I think we are probably looking at it in very different ways. Your viewpoint seems to be coming from the scientifically accepted premise that because we have no way of measuring anything prior to the big bang we might as well discount it (badly paraphrasing Stephen Hawking!) whereas I am looking at it from the point of view that our instinctive concept of time is that it is something that moves in one direction and every moment in time has a period that came before it. At the instant of the big bang it is therefore intuitive to assume that something existed before it. Whilst that previous time period doesn't exist within the confines of what we understand to be our universe it does not mean that there wasn't something going on before that universe came into being.

[andrew s]

19 minutes ago, DRT said:

whereas I am looking at it from the point of view that our instinctive concept of time is that it is something that moves in one direction and every moment in time has a period that came before it

Your right we do have different perspectives but that's a good thing. My personal problem with just instinctive or intuitive concepts is that they are often wrong when taken beyond our day to day experience to the very small e.g. QM or the very large e.g. Cosmos. That in no way is intended to invalidate your or similar views, it is just my personal reading of it..

For what it is worth "time" is the least understood or agreed upon of the basic concepts of hard science. I suspect it will be at the epicenter of any future revolution in our understanding of reality.

I don't think I can add anything new to this debate so may have to start a new one - say on the understanding of time in physics (as opposed to poetry). Assuming I find time to do it.

Regards Andrew