Does Space really go on forever?

[Cidermaker]

Originally Posted by faroutman

Cidermaker, how do you know this?

If I think of myself as 2d on Earth, I go around and around, never finding an end, but that's because I can't comprehend jumping. It would never occur to me to move out. There is no 'out' to me.

Must be the same thing in the universe.

If space is expanding, there must be something beyond space, or the space does not exist, we just can't comprehend how to get there.

You don't need to know, or be able to know, anthing about any higher dimensions in order to say that the space is curved, or indeed flat. Perhaps a better way to put it is to say the geometry in the space is such-and-such, and then you don't have to talk about curvature. For example, if the angles inside a triangle add up to 180 degrees, you can call the space "flat", but if they add up to more, you can say the space is curved. You don't need to know anything about any other dimensions or embedding spaces to notice that the angles do or don't add up to 180 degrees. "What's outside" then becomes a philosophical, and very futile question: if you can't interact with it, it effectively doesn't exist as far as you are concerned.

It's hard to imagine a curved space without it curving into anything, but actually it is equally hard to imagine a flat space without it having anything flat to be flat in. The arguments about geometry above, though, allow you to think about it more objectively.

All this, though, is just about what is conceptually possible. It is quite another question to ask what actually is (and I think I've already held forth about best current knowledge in an earlier post).

[mantajohn9]

Originally Posted by Birchy

hi there, its my first new thread and my first post on the astonomy forum. Normally I'm browsing the bird forum.

Am interested in space, planets, ufo's etc. But don't really have a brillant knowledge of this subject. I just wondered, even though nobody actually knows, if space just goes on forever?
I know that space is MASSIVE!!!!!! But how can something go on and on and on without there been an end. When I think about it, I just end up getting head ache becuase I don't get it.

If there's any experts out there, if you don't know the answer, could you make suggestions at to how space might possibly end.

I probably reckon that this subject has been discussed before but I haven't been a member of the forum for that long.

Assuming that space has a beginning an end (a big can of worms) these are some calculations that I have done with my year 8 physics class:

The distance from the Earth to our moon is 382,260 Km or 237,001.2 miles. This is the furthest that humans have travelled away from Earth.

The distance to Venus (our closest planet) is 42,000,000 Km or 26,000,000 miles at it’s closest point.

A light year is the distance light travels in 1 year

Speed of light = 1 079 252 848.8 km/hr

There are 8766 hrs in 1 year

1 light year = 9 460 730 472 580.8 km

"Nine trillion four hundred and sixty billion seven hundred and thirty million four hundred and seventy two thousand five hundred and eighty thousand point eight kilometres"

After the sun our nearest star is Proxima centauri 4.24 light years away.

4.24 ly = 40 113 497 203 742 .592km

= 24 925 371 582 298 . 496 miles

Space shuttle on average travels at 17 500 mph

To reach Proxima centauri it would take the space shuttle 162 480 years

The object furthest away that is visible with the naked eye is the Triangulum galaxy which is 3.14 million light years away.

Making the big assumpition that the universe has a finite shape it is reckoned to be 24 gigaparces or 78 billion light years across.

But then again if does have a finite shape what is beyond? My brain is melting

[Les E]

HI There,
The Universe does go on forever it cant do anything else ,not only that it has always existed both in space and time and always will.Our Big Bang is only one of a infinate number of Big Bangs that have occured and there are a infinate number of Big Bangs going off right now in a infinate number of parallel Universes.The question posed by those who believe in the infinate Universe is that it must mean that there are a infinate number of ourselves doing exactly what were doing right now.
Regards Les.

[gaviston]

Originally Posted by Les E

HI There,
The Universe does go on forever it cant do anything else ,not only that it has always existed both in space and time and always will.Our Big Bang is only one of a infinate number of Big Bangs that have occured and there are a infinate number of Big Bangs going off right now in a infinate number of parallel Universes.The question posed by those who believe in the infinate Universe is that it must mean that there are a infinate number of ourselves doing exactly what were doing right now.
Regards Les.

I don't agree with that but I don't see why there can't have been other big bangs much too far away for any telescopes to pick up.

Now I'm not religious but the very first ingredient that later was part of the reason for the big bang, that couldn't have just magically appeared from nowhere and whatnot?

I believe space does end somewhere and probably it ends where heaven and hell begin.

[gaviston]

Originally Posted by mantajohn9

Assuming that space has a beginning an end (a big can of worms) these are some calculations that I have done with my year 8 physics class:

The distance from the Earth to our moon is 382,260 Km or 237,001.2 miles. This is the furthest that humans have travelled away from Earth.

The distance to Venus (our closest planet) is 42,000,000 Km or 26,000,000 miles at it’s closest point.

A light year is the distance light travels in 1 year

Speed of light = 1 079 252 848.8 km/hr

There are 8766 hrs in 1 year

1 light year = 9 460 730 472 580.8 km

"Nine trillion four hundred and sixty billion seven hundred and thirty million four hundred and seventy two thousand five hundred and eighty thousand point eight kilometres"

After the sun our nearest star is Proxima centauri 4.24 light years away.

4.24 ly = 40 113 497 203 742 .592km

= 24 925 371 582 298 . 496 miles

Space shuttle on average travels at 17 500 mph

To reach Proxima centauri it would take the space shuttle 162 480 years

The object furthest away that is visible with the naked eye is the Triangulum galaxy which is 3.14 million light years away.

Making the big assumpition that the universe has a finite shape it is reckoned to be 24 gigaparces or 78 billion light years across.

But then again if does have a finite shape what is beyond? My brain is melting

That's amazing really. "Proxima centauri" where is that in the sky?

[mantajohn9]

I'm not an astronomer but if you google earth it you can find it as part of the alpha centauri system. Apparently it is tiny compared even to our sun and has only a fraction of the luminosity so cannot be seen with the naked eye.

[gaviston]

Until puny humans can think themselves somewhere such stars will be out of reach, which is good if it's a star but not good if it's o.0hu9 or similar class planets.

[Les E]

HI Mantajohn,All,

The Alpha Centauri system which are our nearest stellar neighbours comprise of three members in a binary system.Alpha Centauri A which is almost identical to the Sun.Its slightly more massive 20% larger and half as bright again as our star but has a identical G2 spectrum and surface temperature.Alpha Centauri B is about 3/4 the size of the Sun and is a cooler orange K type star and half the Suns luminosity but still bearably Sunlike.Proxima however is a feeble red dwarf 60,000 times fainter than the Sun.Most of the Galaxy is made up of these red glow worms which are only visible because of their closeness.Most of the bright stars visible in the night sky are distant bright searchlights.
Regards Les

[cat72uk]

its just taken me an infinite time to read all these posts
well 1 1/2 hours

[Flying Astronomer]

But then again if does have a finite shape what is beyond?

A lot of misunderstanding here!

Space is a word we usually take to be synonymous with 'empty space'. We might call 'outer space' empty, because there's no air and no apparent matter present.

But in cosmology, space is a thing - a fabric that has physical meaning and existence. So the universe consists of space and all the things within it. Outside the universe, there is no space. There is nothing whatsoever (not even a vacuum, time, nothing). It is beyond our normal understanding, and I can think of no real analogy, to comprehend in any meaningful way what this 'nothing' is.

Rest assured that the physics and maths are well-understood, and that the universe is in fact not expanding 'into' anything. The problem is that we do not experience such a thing in our lives, so we always imagine this wrongly.

J.

[Flying Astronomer]

Originally Posted by zan

I'm curious as to what's (who's?) in the other 8 dimensions we can't see yet

We are! Those extra dimensions are currently believed to be curled-up into extremely small, complicated spaces that are, like much of cosmology, difficult to comprehend in everyday terms. You can think of them as very complicated origami shapes - but very small. I suppose most of us think of them as somehow being isolated from our normal four dimensions, but they are most certainly not! They are part-and-parcel intertwined and inseperable from the three dimensions of space and one of time. In other words, we don't exist within four dimensions, but, most likely, about 11.

When you move around, you are in fact moving through all these 'extra' dimensions (they're not really extra, only to out historical understanding of space). You don't perceive them because they are incredibly small. If you think deeply about it, you don't actually perceive our normal four dimensions, other than your ability to move through them (in only one direction, in the case of time). You can't touch the three space dimensions, any more than you can touch time. You just move through them.

Again, there are good maths to support the theory, but it doesn't always mean that this is the final solution. There may be others solutions. But it is very likely that there are several more dimensions than the four we are used to (3 of space and 1 of time (time may have emerged from a spatial dimension in the first super-billionths of the universe's history).

[Jim Ford]

The initial event when space-time was created is usually referred to as 'The Big Bang'. I find this really quite unhelpful, partly because as has been previously posted, a bang implies an expansion, and an expansion implies a region into which the expansion is increasingly occupying.

I think that as the initiating event for the creation of our 'dollop' of space-time was a totally unique event for us, it requires a totally unique name that doesn't carry any connotations of any other event since. Ideas for a name, anyone?

Jim

[the young hunter]

'The Big Happening'?

That's the closest thing I can think of to discribe it


mike