Does inifinte space & random matter => inifinte matter ?

Syth

Assumptions: Our universe has inifinte space.
Matter in our universe is distributed randomly.

Does this mean that there is infinte matter?

I'm haveing a discussion with a friend over this. I say yes, he says no. I think it does imply infinte matter, becasue on a large scale random is roughly equivilant to evenly spread out. So if you had finite matter, then all the matter would be spread out so thin that you'd have virtually have zero density at any point. So to have a non-zero density, you have to have infinite a matter.

I'd put this on the Space board, but I feel it's more of hypothosing game. A What If senario. Anyone have any contributions?

DeVore

I think some of your assumptions are wrong.

The universe is expanding, at what rate is in dispute but everyone agrees that its expanding.

New matter is not being created (at least not from nothing). Energy and matter are interchangeable (thanks Einstein!) but it cannot be destroyed or created, only its form can change.
I cant speak for dark matter or dark energy but I expect they follow the basic laws of physics too.

So, since the universe is expanding, and matter is relatively constant, the average distribution of matter is getting lower.

Entropy wont allow planets and suns to exist for ever so they explode or get smashed etc. The theory is that eventually there will be a uniform distribution of matter which black holes will hoover up. (at least thats the main theory).

I dont think there is infinite matter, but you have to consider that matter changes to energy and back to matter again sometimes. You're question should really be: Is the sum of energy/matter infinite.

My personal thought would be: No. but its hard to prove such things.

DeV.

Capt'n Midnight

AFAIK we can't prove the universe is of finite size because all observable effects happen at or below the speed of light.

If it could be show that there were vast expanses of nothing at the edges of what we can see then it might suggest a finite universe (but would not prove it)

Have a look at the Hubble Deep Field Picture... what we can see is big enough.

=========================================

1. Area: Infinite.

The Hitchhiker's Guide to the Galaxy offers this definition of the word "Infinite." Infinite: Bigger than the biggest thing ever and then some. Much bigger than that in fact, really amzingly immense, a totally stunning size, real "wow, that's big," time. Infinity is just so big that, by comparison, bigness itself looks really titchy. Gigantic multiplied by colossal multiplied by staggeringly huge is the sort of concept we're trying to get across here.


2. Imports: None.

It is impossible to import things into an infinite area, there being no outside to import things from.


3. Exports: None.

See Imports.


4. Population: None.

It is known that there are an infinite number of worlds, simply because there is an infinite amount of space for them to be in. However, not every one of them is inhabited. Therefore, there must be a finite number of inhabited worlds. Any finite number divided by infinity is as near to nothing as makes no odds, so the average population of all the planets in the Universe can be said to be zero. From this it follows that the population of the whole Universe is also zero, and that any people you may meet from time to time are merely the products of a deranged imagination.


5. Monetary Units: None.

In fact there are three freely convertible currencies in the Galaxy, but none of them count. The Altarian Dollar has recently collapsed, the Flainian Pobble Bead is only exchangeable for other Flainian Pobble Beads, and the Triganic Pu has its own very special problems. Its exchange rate of eight Ningis to one Pu is simple enough, but since a Ningi is a triangular rubber coin six thousand hundred miles along each side, no one has ever collected enough to own one Pu. Ningis are not negotiable currency, because the Galactibanks refuse to deal in fiddling small change. From this basic premise it is very simple to prove that the Galactibanks are also a product of a deranged imagination.


6. Art: None.

The function of art is to hold the mirror up to nature, and there simply isn't a mirror big enough---see point one.


7. Sex: None

Well, in fact there is an awful lot of this, largely because of the total lack of money, trade, banks, art or anything else that might keep all the nonexistant people of the Universe occupied.

However, it is not worth embarking on a long discussion of it now because it really is terribly complicated. For further information see Guide Chapters seven, nine, ten, eleven, fourteen, sixteen, seventeen, nineteen, twenty-one to eightyfour inclusive, and in fact most of the rest of the Guide.

Syth

I'm not trying to prove a new theory on our universe. The assumption may/may not be true for describing the universe. I'm merly trying to do a What-If? I don't really care if it's true or not.

The reason I'm asking is because if it's true (infinte space & infinte matter) then there are infinte earths with ever possibile combination of people and what-nots. Also there would be inifinte possible matter combinations. So some where out there is a star shaped like a square (OK it'd probable have collapsed by now...)

This came about becasue I asked a friend if there was infinite space & random matter and that'd imply infinte earths etc. He said it'd only imply it if there was inifite matter. I'm just wondering that if there if infinte space and random matter does that imply infinte matter. It's just a way of cutting down on the number of assumptions. Always good whenever you're developing a theory.

DeVore: I think it depends on what you mean by expanding. I heard (in relation to the big bang) that it kind of means that all matter and space are moving away from each other, since matter effects space (by bending it) and space effects matter (by making it move, ie gravity). So it's like there is infinte space but it's squashed together. Like the way there are infinte real numbers between 0 and 1, and there are also infinte amount between 0 and 100 (the universe after some expansion).

bonkey

Syth - unfortunately the answer lies in how you choose to define your question!

It is possible to take a finite amount of matter and distribute it randomly across an infinite space.

This is also true for an infinite amount of matter.

Therefore, infinite space which has (an unspecified amount of) matter distributed randomly through it does not necessarily imply an infinite amount of matter, nor does it rule it out.

jc

Capt'n Midnight

doesn't matter 'cos only those in the observable will ever be able to contact us.

Note: a civilisation on the other side of our observable universe might be able to see things we can't. But they can't tell us about anything we can't see - because by the time the message arrived from them we'd see it outselves...

Putting a finite amount of anything in an infinite universe would yield an average of zero.
see point 4 (population) above.

NO there are no square stars - even taking into account unlikely events happen the effects of graviataion make it impossible .. the sort of energy required would be similar to creating a child universe..

bonkey

Originally posted by Capt'n Midnight
Putting a finite amount of anything in an infinite universe would yield an average of zero.
see point 4 (population) above.

Actually, point 4 above is wrong.

In an infinite universe, the population density would tend to 0, while the population itself would be infinite - and not 0 as you (or the HHGTTG) stated.

Not only that, but your assertion that a subset of an infinite quantity must be finite is also erroneous.

If there is an infinite number of planets, then just because not all of them are populated does not imply in any way that there can only be a finite number of populated planets.

As a simple example of why its wrong, I could use your logic to say that not all numbers are integers, therefore there is only a finite amount of integer numbers.

doesn't matter 'cos only those in the observable will ever be able to contact us.

Except that an infinite universe would radically change the definition of "observable", as you would also have to abandon the notion that it all started with the Big Bang, at which point there is no upper limit of time for the origination of signals being received.

In a finite universe, with a fixed start-point, we can deduce that no signal could exist which originated before the big bang. Ergo, without breaking the speed of light, there is a limit to how far a signal could have travelled since the beginning of the universe. This leads to a conclusion that what is observable is limited by the age of the universe, more significantly than the universe's size.

In an infinite universe, there is no argument which allows it to all have been created by our Big Bang. This means that there is no limit on how far away a signal-emitter could be from us, nor how long ago it may have started emitting. As a result, the observable is - by logical extension - also infinite.

Capt'n Midnight

since the fabric of the universe is expanding more or less evenly and you can't find the centre of the universe it can be shown that for someone who is at the edge of our visible horizon would also feel that they were at the centre of the universe - the visible horizon being the 2K background ...

(imagine that you can see a galaxy in 10Bn years away - why should it be at the edge of the universe - surely it can see us and another galaxy equally far away in the opposite direction...)

The reason for supposing a finite amount of matter is that the probability of spontaneous generation of a universe decreases as the energy content rises. To generate an infinite amount of matter would require you waiting for an infnite amount of time - ie. it would never happen. So my guess is the universe is finite - but extends far beyond our visible horizons.

How probably is an infinite probability generator ?

Capt'n Midnight

A. Because it proves that either the age and/or size of the universe is finite.

(size could be interpereted as amount of matter)

Capt'n Midnight

Using that data, the UAH team was able to determine that the speed of that light didn't fluctuate by more than a few parts in 10E-32 as it traveled across the cosmos.

They said if the instant of creation was also a quantum event, when space and time were both blurry, then you don't need infinite density and temperature at the start of the Big Bang.

"If time moves along like business as usual even at Planck scales, however, you have to reconcile the Big Bang model with an event that isn't just off the scale, it's infinite!"

disco_rob_funk

Black sky? What if there are things/stars/galaxies whose light hasn't reached us yet? Or does that imply that they went faster than light at some stage?

What really pisses me off is that supposedly the universe etc. is about 14 billion years old, but how the hell does one define time (reference frame etc.) with all the crazy crap happening during and after the big bang? shiit's being thrown out at nearly c, there's all sorts of antimatter/dark matter/phantom energy hocus-pocus going on, how can you measure such a thing?

I'm sure you could simply say "take the rate at which the universe is expanding, work back, blah blah one over hubble's constant etc...." , but what of it when you work back to when the gnarly shiit was going down?

BTW; I reckon it's a finite, bounded, Riemannian universe expanding into nothing. Currently.

RC

P.S. just had a thought; if it was riemannian, surely the night sky WOULD be bright, i.e. every line of sight ending upon a star.....any ideas?

GuanYin

Originally posted by disco_rob_funk
, how can you measure such a thing?

Something to do with radioactive decay I think.

Incidently, the Raleans made everything, not the big Bang. Pfft!

disco_rob_funk

Yeah ok that's the cosy definition for some dude in a lab measuring the length of a second (see other thread); but given time dilation from special rel., and all the funky stuff happening during the big bang, with the whole lack of inertial reference frame, what of it?

RC

Dampsquid

The universe is expanding, at what rate is in dispute but everyone agrees that its expanding.

If the universe is expanding, then surely it can't be infinite now. Infinite is infinite, it can't get any bigger.

Now there can't be infinite matter, cos the density would have to be infinite, and its clearly not.

A finite amount of matter in a infinite universe would mean that there is zero matter density. Thats not true either. So therefore the Universe isn't infinite.

MarVeL

But whats to say that there is a finite amount of matter?

(and here we go round again)

Capt'n Midnight

even vacuum has properties & dimensions - the universe is not expanding into a vacuum - it's inflation on a large scale - the atoms are not getting further apart (how could we measure that ??) but galaxies are..

Doppler shift / hubble constant - work backwords two things appear:
a) 12.5 bn years give or take
b) you can't say which point was the centre of the universe since everything is expanding in relation to everything else - if there was a centre of the universe then everything would expand away from it.

The universe is infinite in the sense that we can't get out of it - and it would take at least 12.5 Bn years travelling at very close to the speed of light to the visible horizon before we could tell if anything past it - and another 25 Bn years for the reply to reach earth (and another 50Bn years before we get an acknowledgement back from earth - by which stange the stars would be kinda dim)

PS. speed of light in a vacuum is constant and nothing can go faster - also does not matter which reference point you measure it from it's still the same speed - so in an infinite size & age universe the sky would be white (even if it was covered in dust)

bonkey

Originally posted by Dampsquid
If the universe is expanding, then surely it can't be infinite now. Infinite is infinite, it can't get any bigger.

Not so.

The list of integer numbers is infinite.
The list of all numbers (integer and non-integer) is a larger infinity.

Indeed, there is an entire "hierarchy" of infinities. So just because something is infinite, doesn't mean it can't grow or shrink.

The universe is infinite in the sense that we can't get out of it

Also not so. Not being able to "get out of it" does not imply that it is infinite.

For example, by reducing the number of dimensions....the surface of a sphere cannot be "gotten out of" when discussing a curved 2-d space. It is by no means infinite - but it is unbounded in that there are no edges.

PS. speed of light in a vacuum is constant and nothing can go faster - also does not matter which reference point you measure it from it's still the same speed - so in an infinite size & age universe the sky would be white (even if it was covered in dust) [/i]

Not so certain on this one, but again, I would be inclined to say "not so".

The reason offered for a "white sky" is that in an infinite universe, no matter which way you look, your point of view will always end up "hitting" matter...which traditionally has meant "a star". Ergo, no matter which way you look, there should be light emanating from the direction you are looking in, coming towards you.

What this would mean is that rather than seeing stars amongst the background, we should see nothing but stars.

However, the "white light" argument is dependant on a static infinite space-time universe - i.e. no expansion or contraction of "sub-sections" of the universe or of the whole universe itself. With expansion, and ensuing effects such as red-shifting, there is absolutely nothing to suggest that the sky should be white. Indeed, what would appear to be suggested is that there would be an almost constant background level of emissions at and below a certain level of "activity"...which is funnily enough what we do see (and which is consistent with a non-infinite universe as well)

Of course, to make such an assertion would require that we also assert that every part of the infinite universe obeys the same laws of physics as we do here - which is somewhat counter to many other theories about infinite universes.

jc

disco_rob_funk

Right at the start, are we talking countably or uncountably infinite here?

(aleph-zero or aleph-one, the first & sencond transfinite cardinals (!) to the nerds)

Uncountable would allow for infinite worlds, possibilites, realms, etc, as mentioned by bonkey above.

Countable would mean there are loads of plaents,galaxies etc, but all part of the same realm/existence/timeline etc.

Also in the same post, a good description of "Riemannian" space not implying either finite or infinite, much like our earth is clearly finite, but keep travelling along the deck and you still can't get out of this kyp!

As for the "cetnre of the universe" yoke, surely the singularity from the origin of the big bang would be the centre of our universe; like the model of the inflating balloon, everything expanding away from everything, but a well-defined centre.

Or is that too easy?!

RC

Capt'n Midnight

In which direction is the centre of the universe ?
When you understand the answer to that you should have a good grasp of inflation.

http://hubblesite.org/newscenter/archive/2003/19/
At an estimated age of 13 billion years, the planet is more than twice as old as Earth’s 4.5 billion years

Look upon it as evidence that the universe is not infinitely old.

The universe is also flat as far as we can tell..

Dampsquid

As for the "cetnre of the universe" yoke, surely the singularity from the origin of the big bang would be the centre of our universe; like the model of the inflating balloon, everything expanding away from everything, but a well-defined centre.

The balloon model for an expanding universe is that the actually balloon surface is the universe, not the air inside it. So if we were on the surface of the balloon then there would be no centre because nothing exist off he surface.

bonkey

Originally posted by Capt'n Midnight
The universe is also flat as far as we can tell..

I would have said that virtually all of our models call for a curvature in one aspect or another. The only possible exception I can think of is Quantum theory, and given that it can't handle gravity (which curves space-time under relativity), I hardly think its anywhere near a complete enough theory to base a belief that "the universe is flat" upon it.

Are you perhaps thinking of the notion that the theorised shape of matter in the universe is - in actual fact - a flattish disk ???


jc

Capt'n Midnight

within experimental error and to lots of dp's

Capt'n Midnight

31495448272550005155211307922363110936089435829054233418732462850152371262062592

According to Arthur Eddington in his book Mathematical Theory of Relativity (1923, London, Cambridge University press)

(though let us not forget Prot - he postulated that ALL matter was made in a certain way - 90% of the observable universe is named after the wrong guy...)
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6.2E10^243
The four-dimensional volume (in space + time) of the known universe using the formula for the volume of a hypercone (with spherical cross-section) and the universe's age, expressed in Planck units. The hypercone volume formula is
V = (1/4 h) (4/3 ƒÎ r3)
where h is the height of the hypercone and r is the radius of the sphere that forms the hypercone's base. h is the age of the universe in Planck time units and r is its current radius in Planck length units.

======================================


6.2E10^340
If you chose a random particle in the known universe, then chose a random moment in the universe's history and moved the particle to a random location somewhere else in the universe at that moment, you would have a total of 6.2 ~ 10340 distinct choices (as limited by the uncertainty principle). Moving a particle instantly by a large distance would usually violate Einstein's relativity (by exceeding the speed of light), but "particles" moving at faster than the speed of light must be considered when modeling physics by one of the gauge theories such as Quantum Electrodynamics.

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6.2E10^340! (factorial) gives the total number of complete shufflings of the entire known universe's history.

So this number is a good definition of infinity from our perception - it defines all possible observable universes (as old as ours ) from our perspective..
REF: http://home.earthlink.net/~mrob/pub/math/numbers-10.html

SOL

There cqnt be infinite qnything becquse if the were to be then for every qction the would be qn infinite probqbility of qn eauql reqction thqt would stop it qnd so nothing would hqppen

Capt'n Midnight

suggest you look up the phrase "escape velocity"

Even if the average momentum in a system is constant, things can happen (and frequently do)

If however, there was a "GREAT ATTRACTOR" then unless it had infinite mass , most of an infinite universe would be far enough away that it's gravitation effect would be slight - and even then there is quite a range of velocities for stable orbits..

SOL

And that has relevance to what? If there is an infinite ammount of it it will all collide ?