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memo
2003-Dec-20, 02:01 AM
We all know the big bang theory,but does anyone know which way we are traveling.Say i am facing a sunrise on the east coast are we going in that direction, or if my back is to the sun are we going in that direction.The sun is just for direction not to the sun.Thanks for listening

Matthew
2003-Dec-20, 03:46 AM
The big bang blasted matter in a fairly spherical way. We are not moving relative to the Earth. Relative to the sun we are orbiting our axis and going arount the sun. Relative to the core of the galaxy we are spinning around on our axis, orbiting the sun and orbiting the central core. What I&#39;m trying to say is that you have to have a point of reference.

If you want to are reference for the centre of the universe, no-one knows where that is, if there is one, or if the universe is so interconnected (in a finite universe) there is no centre.

kashi
2003-Dec-20, 08:17 AM
If I understand you correctly, then obviously any direction changes as the Earth rotates. Matthew is correct however, we cannot really think about this in 3 dimensions. The universe is really expanding in all directions like dots painted on the surface of an expanding balloon.

TiMiX
2003-Dec-21, 11:29 PM
Do we know how fast the universe is expanding? and is the expanding getting slower?

Cheers :D

Fraser
2003-Dec-22, 12:49 AM
Astronomers believe that the expansion of the Universe is actually speeding up - the mysterious theory of "Dark Energy".

Littlemews
2003-Dec-22, 05:36 AM
Originally posted by TiMiX@Dec 21 2003, 11:29 PM
Do we know how fast the universe is expanding? and is the expanding getting slower?

Cheers :D
13.7 billion yrs ago, the universe expanding like 10 to the -43 sec, then later drop it back to 10 to the -13 sec, and now its like 10 sec :lol:

Matthew
2003-Dec-23, 01:40 AM
I think the speed of expansion maximum would be c.

memo
2003-Dec-24, 03:28 PM
Ok lets try it again.The big bang started from which direction.Facing rhe sunis a direction at sun rise,look past the sun at the same sun rise i look away.Are we moving away in that direction.If you donot know what i mean the quwstion is lost.

2003-Dec-24, 05:40 PM
It is difficult to derive meaning for "the direction we are going" by using the sun as a reference. As the earth revolves about the sun, the direction from the earth to the sun not only sweeps across the entire galaxy but also many directions outside the galaxy and somewhat constrained to the plane of the ecliptic. Unless the direction of motion of the galaxy happens to coincide with the plane of the ecliptic, our motion,galatically speaking, will never be toward the sun at any time of day, year, or galactic year.

The galaxy is in rotation about the center of gravity of the local group. The local group is in rotation about the center of gravity of the "local" cluster which is in rotation about the center of gravity of the super cluster of which it is a member. The super cluster appears, for the cosmological moment, to be headed for the "great attractor" no doubt an illusion caused by the super cluster&#39;s rotation about some unidentified center of gravity.

Having noted all this we still can not state, in an absolute sense, in which direction we are moving. Remember the universe has no center and no preferred direction&#33;

Chook
2003-Dec-24, 06:38 PM
Gourdhead - have you been drinking again&#33;

Happy Christmas&#33; :P

TheThorn
2003-Dec-25, 05:46 AM
Originally posted by nelson marasco@Dec 24 2003, 03:28 PM
Ok lets try it again.The big bang started from which direction.Facing rhe sunis a direction at sun rise,look past the sun at the same sun rise i look away.Are we moving away in that direction.If you donot know what i mean the quwstion is lost.
I think I understand the question. You&#39;re thinking of an explosion like you see in the movies or a battle or something. Pieces being thrown away from a centre. We&#39;re (our sun, galaxy, etc) one of the pieces. So which way is it to the centre?

I think this one is really hard to explain, but there is no centre, or rather everywhere looks like the centre.

Think of a balloon, with spots all over it being blown up. The spots all move apart from each other. The farther apart they are, the faster they moe apart. That&#39;s a two dimensional surface expanding about a point that is not on the surface. The universe is like that, sort of, except it&#39;s a three dimensional "surface" expanding in a fourth (or maybe even higher) dimension.

So you may as well say that we&#39;re at the centre of the universe, and it&#39;s all expanding away from us, because that&#39;s exactly what it looks like. The farther away from here an object is, the faster it is moving away from us, just as if we were the one stationary object left behind by the explosion.

Of course, it looks exactly the same from any other point in the universe too. Same as all those spots on the balloon.

Ultimately, I think the problem is in our imagination. The movie explosion you&#39;re thinking of has a cloud of debris expanding into the area around it. But there is no area around the universe. There is no pre-existing space for it to expand into. So it&#39;s not the same sort of "bang".

damienpaul
2003-Dec-25, 05:50 AM
wow, my head hurts :wacko:

but i think i understand

TheThorn
2003-Dec-26, 04:15 PM
" wow, my head hurts

but i think i understand"

Yeah, well, apparently I didn&#39;t <G>.

On further reading, I have discovered something I wasn&#39;t aware of before. Apparently there is a dipole component to the cosmic microwave background(i.e. it looks "hotter" in one direction than the other). Which means we&#39;re moving with respect to it. But since the cosmic microwave background IS the big bang, that means we&#39;re moving with respect to the big bang&#33; About 600km/sec. In the direction RA 1.5h ± 0.4m, declination +0.2° ± 7°.

Of course, part of this motion is our sun rotating about the centre of the Milky Way, and part of it is the Local Group of Galaxies falling toward the Virgo Supercluster of Galaxies, and there seems to be some discussion of whether there&#39;s any motion left over once you subtract out those known motions.

So, I&#39;ll have to fall back to "I don&#39;t know". <G>

Tiny
2004-Feb-07, 12:39 AM
How commonly is the Big Bang in the universe?
I hear that the big bang is actually a tiny dot, they are everywhere, some explode early, but some explode lately... so is that ture?

The teacher making jokes all the time >.<, therefore can&#39;t focus what shes talking about