Horizon: How Big Is the Universe? (T) Mon 21:00

[DUCky]

As usual, massive food for thought. Another good Horizon

:bluThinki So,

The Universe is flat, not curved.

Its infinitely large

Its measured at a finite 14.5 odd billion years old from the big bang

Light travels at a finite speed


The first two theories contradict the last two in a large(cosmic size) way.

An infinitely large distance cannot be covered in a finite time and at finite speed


Wheres bushcraftin' Brian Cox when you need him?

The mindbender is that you have to take into account that space itself has inflated/grown. I can walk an infite numer of miles at a finite speed within a given space in a finite period if the space I am in has expanded infinitely in that same finite period. Not saying it will be easy

Good stuff

 

[wattsy]

regarding the Universe appearing to be expanding faster than the speed of light imagine 2 stationary ants on a balloon that is then inflated. the ants don't move but they get further apart as the space in between them expands, and as the balloon increases in size so they appear to be moving faster and faster away from each other. thats how my physics teacher explained it anyway

 

[ged]

I once read that strange large 'tubes' of nebula type 'things' had been discovered which were over 100 billion light years long. How could this be in a universe which is supposedly 14 billion light years across.

When you start to think about things that are very, very big (and also, as it happens, when you start to think about things that are very, very small) you have to put aside, or at least leave open to different interpretation, everything that you think you know about things that are, well, 'normal' sized. For the purposes of this argument, things like virus particles, spotty mushrooms and planets are all pretty much 'normal' sized.

The universe isn't 14 billion light years across, that's just approximately how old we think it probably is, and if the light that things emitted 14 billion years ago reaches us this afternoon then we can sort of say that they were 14 billion light years away when they emitted that light. But that isn't where they are now, that's where we think they were 14 billion years ago, and a lot can happen in 14 billion years. In fact a lot can happen in a micro-nano-nano-nano-second.

You might say that if the universe is that old, and if nothing can travel faster than light, then at its biggest it can only be 28 billion light years in diameter. But that assumes that it all started in the same 'place' (maybe it didn't, and what's a 'place' on these scales anyway?) and that the 'rules' were always the same throughout the entire 14 billion years (maybe they weren't, and, if it comes to that, what are the rules?). We're still collecting the evidence, but the more we collect the more it looks like the 'inflation' ideas have a lot to offer. Intuitively, unfortunately, they're a bit like chewing those spotty mushrooms.

I hope you liked my very scientific terminology ...

The terminology doesn't really matter. That's why I called it the big whatsit. What matters is the way that you think about it. It's a whole new ball game.

 

[DUCky]

Good reads for by the campfire:
- Hyperspace by Micho Kaku
- The fabric of the cosmos / The Elegant Universe by Brian Greene

 

[mountainm]

Sounds more to me like de-pressurisation than inflation... but don't get me started on my theories.

 

[HillBill]

1+1 = 2 = 1

Inflation? of a sort. Expansion would more accurately describe it. Infinite expansion? no. It will come up against another equal thing at some point and will create another between them, 1+1=2=1. Or if we are working on totals. 1 + 1=2=3=5=8=13=21=34=56. etc etc. Recognise it?

Big bang? More of a burst water pipe coming up through a drain Only one of many, wasn't the first, wont be the last.

I tried to explain my theory of it ages ago in the fear of the dark thread.

, if it comes to that, what are the rules?).
.

 

[blacktimberwolf]

How did scientists come up with such a precise figure for the creation of the universe ? before the big bang where did the highly compressed matter that exploded come from in the first place & how long did it exist before exploding ? If the universe is infinate, how can it continue to expand ? If there are a hundred billion galaxies each with a hundred billion stars in our universe, are there a hundred billion other universes out side our own ? Will Greece be forced to leave the Euro-zone ?

Thakyou for your answers.

 

[mountainm]

How did scientists come up with such a precise figure for the creation of the universe ?
http://map.gsfc.nasa.gov/universe/uni_age.html

before the big bang where did the highly compressed matter that exploded come from in the first place & how long did it exist before exploding ?
time didn't exist before the big bang, so the question is invalid

If the universe is infinate, how can it continue to expand ?
infinity can get bigger - or smaller and still be infinity. THe coastline of the UK is a fractal, and therefore infinitely long - but you can add another chunk of rock to it and it will be bigger.

If there are a hundred billion galaxies each with a hundred billion stars in our universe, are there a hundred billion other universes out side our own ?
Nobody knows - there could be. There could be an inifinite number of universes. Universes could be born and dying all the time. Or ours may be the only one. We are ants under rocks and we cannot lift the rock to find out.

Will Greece be forced to leave the Euro-zone ?
No, they will realise that smashing crockery is what got them into this mess and invest in rubber plates - thus halting the current crisis. In the end we'll all be rich.

 

[mountainm]

Oh, and this is the Milky way photo mentioned in the programme:
http://galaxy.phy.cmich.edu/~axel/mwpan2/krpano/

 

[santaman2000]

regarding the Universe appearing to be expanding faster than the speed of light imagine 2 stationary ants on a balloon that is then inflated. the ants don't move but they get further apart as the space in between them expands, and as the balloon increases in size so they appear to be moving faster and faster away from each other. thats how my physics teacher explained it anyway

My physics proffessor used the opposit logic:

The ants WERE moving as the piece of balloon they're standing on was moving. Just as you're moving even when you're sitting still in a seat on a train. If you get up and walk from the rear of the train to the front of the train from the rear then you're moving at the compound speed (the speed you're walking plus the speed of the train) Thus the theory of how to achieve FTL (Faster Than Light) speed; get a theoretical train up to light speed, then walk forward on it (or turn on a flashlight in the rear and aim it forward)

 

[ged]

... Or if we are working on totals. 1 + 1=2=3=5=8=13=21=34=56. etc etc. Recognise it? ...

Almost. That last number is wrong.

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

 

[ged]

My physics proffessor used the opposit logic ...Thus the theory of how to achieve FTL (Faster Than Light) speed; get a theoretical train up to light speed, then walk forward on it (or turn on a flashlight in the rear and aim it forward)

Sorry, it doesn't work like that. That kind of thinking is what I said you have to put behind you. Look into 'relativity'.

 

[HillBill]

Typo ....

In the way i'm referring to the sequence starts 1 1 rather than 0 1 1. Nothing can not create anything and the numbers in my sequence are just representaves of "something" zero is just a mathematical figure that cannot be used to represent "anything" other than itself so is moot in the "real" world.

So as far as anything natural is concerned, there can only ever be a minimun of 2, else nothing would exist. You could call it the male and female. The theory applies up and down the scale, to pretty much anything.

Using the theory, if you can get your head round it and understand exactly "how" it works, then all the things science now struggles to gets to grips with will become very clear.

Almost. That last number is wrong.

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

 

[santaman2000]

Sorry, it doesn't work like that. That kind of thinking is what I said you have to put behind you. Look into 'relativity'.

My physics proffessor would disagree with you. At least regarding the possibility of achieving FTL in this way. And he taught relativity.

Although I (and he) agree with you on the concept of space itself expanding differently. Just that the metaphor of a ballon might not have been adequate.

 

[ged]

How did scientists come up with such a precise figure for the creation of the universe ?

We made increasingly precise measurements based on inspired guesswork. It turns out that you can probably rely on a certain type of stellar explosion (a supernova) to be a very particular absolute brightness. It's called a 'standard candle' although candle is hardly the word. Anyway we hope it's right. Knowing the brightness as we see it tells us how 'far away' it is from the inverse square law.

before the big bang where did the highly compressed matter that exploded come from in the first place

It didn't 'come from somewhere'. It didn't exist. There wasn't any matter before that, nor was there anything else. It came into existence, along with a load of magnetic monopoles (which at the time greatly outnumbered all the other particles, and which now seem to have all gone, which is a big part of the puzzle) . Or so we are led to believe, by what we think we can see. It might all be complete tosh.

& how long did it exist before exploding ?

About a nano-nano-nano-nano-second.

If the universe is infinate, how can it continue to expand ?

That's a big if.

If there are a hundred billion galaxies each with a hundred billion stars in our universe, are there a hundred billion other universes out side our own ?

It depends on what you mean when you say 'universe'. If you mean 'everything' (in the same sense that I mean 'everything'), then obviously not. If you don't, then you need to start formulating your questions more carefully.

Will Greece be forced to leave the Euro-zone ?

Isn't that political and thus a banned topic on BCUK?

 

[HillBill]

The tip of the train is travelling at the speed of light. Therefore in order to move ahead of the speed of light you have to be able to take over the train, which is not possible while on it. Its just dragging you along.

 

[mountainm]

Amoeba, doesnt take 2.

 

[santaman2000]

So if you're in your car, driving long at the speed of light, and you turn on your headlights; does it help?

 

[santaman2000]

...It depends on what you mean when you say 'universe'. If you mean 'everything' (in the same sense that I mean 'everything'), then obviously not. If you don't, then you need to start formulating your questions more carefully...

That's the crux of trying to understand this (perhaps "comprehend" is a better word) Not thinking of "universe" and "infinity" as meaning all encompassing. That's really not an easy thing to do.

 

[ged]

So if you're in your car, driving long at the speed of light, and you turn on your headlights; does it help?

Only if it's dark.