A Question

Denerick

Please humour this philistine:

If the universe is infinite, why is it also expanding?

I'd love to hear an explanation for this. It confuses the hell out of me...

Beeker

Denerick wrote: »

Please humour this philistine:

If the universe is infinite, why is it also expanding?

I'd love to hear an explanation for this. It confuses the hell out of me...

Greater minds than I may be able to explain but what make you say the Universe is infinite? I beleive it is finite and expanding.

djhaxman

http://www.astro.ucla.edu/~wright/cosmology_faq.html#XIN

What is the Universe expanding into?

This question is based on the ever popular misconception that the Universe is some curved object embedded in a higher dimensional space, and that the Universe is expanding into this space. This misconception is probably fostered by the balloon analogy which shows a 2-D spherical model of the Universe expanding in a 3-D space. While it is possible to think of the Universe this way, it is not necessary, and there is nothing whatsoever that we have measured or can measure that will show us anything about the larger space. Everything that we measure is within the Universe, and we see no edge or boundary or center of expansion. Thus the Universe is not expanding into anything that we can see, and this is not a profitable thing to think about. Just as Dali's Corpus Hypercubicus is just a 2-D picture of a 3-D object that represents the surface of a 4-D cube, remember that the balloon analogy is just a 2-D picture of a 3-D situation that is supposed to help you think about a curved 3-D space, but it does not mean that there is really a 4-D space that the Universe is expanding into.

I'm still nonethewiser.

Beeker

djhaxman wrote: »

http://www.astro.ucla.edu/~wright/cosmology_faq.html#XIN



I'm still nonethewiser.

Oh my brain hurts!!!!!


:D:D

djhaxman

Beeker wrote: »

Oh my brain hurts!!!!!

I'm heading back to college to study astrophysics in September, so my brain will hurt for the next 4 years!

This question was posted on boards 3 years ago, and no one could answer it back then either!

http://www.boards.ie/vbulletin/showthread.php?p=54393435

Beeker

djhaxman wrote: »

I'm heading back to college to study astrophysics in September, so my brain will hurt for the next 4 years!

This question was posted on boards 3 years ago, and no one could answer it back then either!

http://www.boards.ie/vbulletin/showthread.php?p=54393435

Best of luck to you at college. I always wanted to study astrophysics but the maths scared the sh*t out of me:eek: Still would love to try:)

djhaxman

Beeker wrote: »

Best of luck to you at college. I always wanted to study astrophysics but the maths scared the sh*t out of me:eek: Still would love to try:)

Cheers Beeker. Yeah I did a maths refresher course a couple of weeks back and it shows just how much I'd forgotten. The college (NUIM) were involved with the Herschel telescope and ESA so there may be trips during the summer break there. We also go to Jodrell Bank in 2nd year and some observatory in the Canaries in 3rd year so that should be good.

http://communications.nuim.ie/140509.shtml

Sorry for hi-jacking your thread OP.

riffmongous

Denerick wrote: »

Please humour this philistine:

If the universe is infinite, why is it also expanding?

I think the only way the universe can be infinite is if it is expanding(?)
If the universe didn't start off being infinite, which we assume it didn't with the big bang theory, then the only way it can be infinite is if it expands for an infinite amount of time???

djhaxman wrote: »

We also go to Jodrell Bank in 2nd year

Jodrell Bank is pretty cool, they used to tell a story about how they were picking up some strange signal that they couldn't explain, until someone played it on a television and it turned out to be security camera footage from a bus depot miles away

Whippersnapper

Is it expanding yet contracting at the same time? Is it contracting in on itself from expansion? Sounds straightforward enough!

riffmongous

Whippersnapper wrote: »

Is it expanding yet contracting at the same time? Is it contracting in on itself from expansion? Sounds straightforward enough!

I'm pretty sure its expanding, have you got any more info on the contracting in on itself theory?

ynotdu

riffmongous wrote: »

I'm pretty sure its expanding, have you got any more info on the contracting in on itself theory?

Yep the current experts say it is an expanding Universe........................So where is it expanding to?

as was brought up on a post before the Life and death of a Star aids in getting Yar head around the concept of the big bang>expansion>contraction.

If i work real hard on this and figure a solution i wonder will boards award Me an extra star

wylo

djhaxman wrote: »

http://www.astro.ucla.edu/~wright/cosmology_faq.html#XIN



I'm still nonethewiser.

I cant stand the balloon analogy because I just simply cant imagine the same thing in 3D.

Also what about these images of the some of the oldest light in the universe, where are they getting these pictures and why isnt that 'the edge' of the universe?

djhaxman

wylo wrote: »

I cant stand the balloon analogy because I just simply cant imagine the same thing in 3D.

Also what about these images of the some of the oldest light in the universe, where are they getting these pictures and why isnt that 'the edge' of the universe?

The image you posted is the latest image from the Planck space telescope that is measuring the Cosmic Microwave Background Radiation - the leftover radiation from the Big Bang. That is the earliest light in the universe, which is so old, cold and redshifted by the expansion of the universe it is no longer visible with regular telescopes.

Tbh I don't know enough about all this to answer your question properly. Light travels at an finite speed - which means it has only been travelling a fixed amount of time, therefore we are restricted by seeing further than x light years. The CMBR is from when the universe was about 380,000 years old so is some 13.7 billion years old. However due to the expansion of space, the observable universe is something like 90 billion light years across. Is that the real edge of the universe? We don't know.

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

bytey

djhaxman wrote: »

The image you posted is the latest image from the Planck space telescope
http://en.wikipedia.org/wiki/Observable_universe

no its not , thats an old image produced by previous research on CBR
using the Wilkinson Microwave Anisotropy Probe

get your facts right .

Denerick

AAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHH!

You have not made the confusion go away!

djhaxman

bytey wrote: »

no its not , thats an old image produced by previous research on CBR
using the Wilkinson Microwave Anisotropy Probe

get your facts right .

Whatever. Lose the tone, at least I tried to give an explanation.

Redshift

Please keep it civil, as they say on other fora "Play the ball not the Man"

Thank you

Whippersnapper

A podcast that may be of interest:

http://www.astronomycast.com/cosmology/episode-28-what-is-the-universe-expanding-into/

rccaulfield

With the multiverse theory, wouldn't there be plenty of void for the edge of the universe to expand into? i.e. an infinite amount of universes sharing space perhaps in bubbles in water form?
Second explanation is like our eyes not being designed to pick up most frequencies of rays, our minds cannot understand the concept of a wall with nothing on the other side, likewise a beginning with nothing before it ala the big band theory. Maybe we'd better start getting used to it?

gentillabdulla

If the universe started from the explosion of a black hole then it implies that the universe is not infinite.(At least to me that is.)

Here is why I see it like that.


If all the spacetime was warped severely into a single black hole then it would stop the gravity keeping the black hole together.

Then explode.

Soon as most of the massive stars cool down and become black holes they start to destroy the mass around them to gain gravity due to the increasing of mass.

AS this mass increase so does the warp in spacetime causing the fabric of spacetime as we know it to contract with the increasing magnitude of gravity.

And as soon as all the mass becomes one black hole then all spacetime goes into the object.

And as we have stated before once that happens another explosion occurs due to the loss of spacetime warp.(Gravity cannot occur without spacetime.)

But this is assertion and should be treated as such.

bytey

djhaxman wrote: »

Whatever. Lose the tone, at least I tried to give an explanation.

pardon me for pointing out a scientific fact in a supposed science forum


in any case

likely is that the universe folds back onto itself
so that there is nothing outside the universe
where ever you go in it - you are in it , you cannot go outside it , it has no edge .
its infinite because if you travel long enough in it you will reach the point you began from . like a circle ( which is infinite )
and - this is the important part -
it expands into itself

the 3d universe really crys out for another dimension to contain it , for it to expand into
and this may be the case - a 4th or 5th dimension ( if time is the 4th dimension then lets call it the 5th dimension )

this 5th dimension is actually part of the 3d dimensional universe down to the very tiniest structure in the 3d universe ( ie whatever makes up the actual space between sub atomic particles - hence the universe expands into it self by the 3d universe expanding into the 5d dimension that constructs it - and as it expands , more 5d is available for the 3d to sit in.

djhaxman

bytey wrote: »

pardon me for pointing out a scientific fact in a supposed science forum

Pardon you? I've checked some of your previous posts and it seems like you have the same attitude towards other posters in most of them so maybe it's just your style. You were correct, it was my mistake but I didn't like your way of replying. There's no need for you to be a **** towards others all the time.

Tomk1

Basically the problem with the initial Q is the natural assumption that something exists outside our Universe, apart from other dimensions.

Space-time and the whole Universe began with the BB. The mass of the universe has just been spread out as the universe-bubble expands with what could be described as the creation of new space-time.

One of the problems is trying to use a form of relative measurement (which is irrelevant wrt huge speeds), to measure the size of the universe.

Looking the whole idea of infinity of the Universe, you would have to take into account the future states of the Universe, if the universe is closed then at some point it will be finite, if the universe is open then it will be infinite to the end point of consisting only of bland photonic particles. If the Universe ends up with the Big Shrink then it must be the opposite polarity of infinity (??? anti-infinity???)

Now one of the things that defines an object is its mass, if the mass is constant then a finite mass, the size....the spreading out of the mass.
Is the idea of infinity finite or an idea infinite?

The problem with infinity (btw great film) is, its kind of big.

Denerick

Tomk1 wrote: »

e size of the universe.

Looking the whole idea of infinity of the Universe, you would have to take into account the future states of the Universe, if the universe is closed then at some point it will be finite, if the universe is open then it will be infinite to the end point of consisting only of bland photonic particles. If the Universe ends up with the Big Shrink then it must be the opposite polarity of infinity (??? anti-infinity???)

.

Oooooh! Is that the intellectual base of 'the nothingness' in that god awful Disney film fantasia???

sbsquarepants

I too find this one totally baffling.
I have a real problem with the very concept of infinity, i don't believe anything can be infinite, except in an abstract mathematical sense. Problem is i also find the very concept of nothingness hard to take, even if there is a complete lack of anything there must be a boundary, and aboundary must be made of something?
I believe the universe must be finite, there can't have been infinite mass and infinite energy at the point of the big bang, due to the simple fact that infinity is a concept not a quantity, once you quantify it and say there was x amount of material then thats not infinity (ie there could have been 10 times as much). If it's finite there has to be an outside. PARADOX! (well to me it is anyway:))
I've been trying to get my head around quantum theory lately, in a broad theory kind of way, not detailed mathematics and i find the theory of quantum entanglement fascinating. It appears that the speed of light is no more of an absolute limit than a 120kph signs on the motorway.
I think we are in our infancy of understanding who and what we are, how we got here and how things work. I think relativity etc, suits us now cos it matches what we see, but saying the world was flat matched what we saw at one stage, as we find new ways of looking we see the old theory wasn't right.
Bottom line is, we don't have a clue what the universe is, where it came from or where it's going, what it's made of or why it works the way it does, maybe we never will!
Maybe the flying spaghetti monster made it after all!

thecommander

Infinity + 1.

Rubecula

I have lost the post I was looking at, but I think someone was asking how if the universe in infinite can we say we NOT see so much of it.

Or something like that anyway.

Basically, and I am ready to be shot down in flames here, the universe is thought to have originated in a 'Big Bang' 13.5 billion years ago.

We can only see things in the visible spectrum (OK we can also see in X ray IR and such using telescopes of various kinds) and the spectra travel at the speed of light.

Therefore the limit of things we can see is 13.5 billion light years away. If there is anything further away than that, it is too far for the light to have yet reached us.

What we can observe is in the best possible circumstances a 'globe' with a radius of 13.5 billion light years.

If the universe we are in is infinite, we have not had the infinite amount of time required to observe it. In fact if it is actually any bigger than what we observe, we will be unable to 'see' it.

Hope that makes sense.....

rccaulfield

bytey wrote: »

its infinite because if you travel long enough in it you will reach the point you began from . like a circle ( which is infinite )
and - this is the important part -
it expands into itself

.

Yea but don't circles have boundaries(edges?) and therefore are not infinite?