h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

How big is the universe? Measure it as you will,
it's precisely one world wide.
How much does it weigh? Naught on the dot.
That's nothing, and you can check it out.

Just in case anyone asks.

Depends on what you mean by "world." It's also, of course, ten billion light-years wide.

Current theory has it that the Universe started about 12 billion years ago but as it initially expanded at speeds far in excess of the speed of light then it would be much more than 10 billion light years wide. That said I have no idea how big it is, but pretty big.

I thought nothing could travel faster than light.

No, nothing can travel faster than light at least thats the current opinion. As far as I know no-one knows exactly how big the Universe is or what its mass is although lots of estimates have been made. The only thing we can know is the size and mass of the obsevable Universe (the figures doesnt immediatly spring to mind however), anything beyond this we literally cannot 'see' as the light hasnt reached us yet. Estimates on the total mass and size are based on rates of expansion and lots of other complicated stuff.

It can't. As far as I know. But the universe doesn't expand in that way. The reason for the expansion is that space itself expands - more nothingness is created all the time inbetween all the stars and galaxies and stuff.

...so I suppose you were right in assuming that *nothing* can travel faster that light.

I didn't think nothingness was constantly created--I thought that the matter in the universe simply moved apart.

It does move apart, as a consequence of the expansion of space. But the matter doesn't move in space, space just gets bigger, thus causing the distance between two objects to increase anyway.
Thats how I remember it from Modern Physics...after that it got *really* confusing

I agree with Freedom....like blowing up a balloon with two ants on it. The balloon's surface is space, the ants get further apart as it expands.

Out-of-Nowhere started this and then disappeared, like starting off an expansion and then getting further away him/herself. Neat trick OoN.

Yeah, the universe is constantly expanding, but whats the point? If space is constantly expanding it must have a constantly expanding size, so you could never find out how big it really was. The mass must have remaned the same since whenever it was created, it isn't creating more matter (is it? I don't know, scary if it was though). Actually, the universe must have been really dense when it was created, if it was all nowhere. Aaargh! Just thinking about it is frying my BRAIN!

Couldn't the mass be increasing? If, say, the universe started off as all energy and then that evergy started to turn into matter, maybe that's still happening.

I think it could, the way I understand it is that the energy content of the universe has to remain constant, and some think this constant value is 0. If matter is equivalent to positive energy (according to Einstein ), then the effects of gravity would be the "negative" energy that causes the sum to remain at 0. So, matter is allowed to exist but it's movement is restricted by gravitational forces. If this is true you could probably add as much matter as you'd like to the universe as long as you didn't let it move about too much.

So to speak. I'm not sure how much sense I'm makin here...

Peace & love

Thanks Lupa, Rickshaw, Andy, Slart, Freedom, Fargo and DJ for your interest. It's a bit of a shame it's died off though as perspective is the essence of existence.

Requeing, is that a word.

Lupa Mirabilis, Devilish Fiend, writes in with: "Couldn't the mass be increasing? If, say, the universe started off as all energy and then that evergy started to turn into matter, maybe that's still happening."

While I am not sure whether energy is turning into matter with any great frequency or amount, I can tell you that the opposite is happening an awful lot throughout the universe. In other words, almost everywhere you look (cosmically speaking) you will see matter turning into energy. This is part of what happens with nuclear fusion, i.e. an elemental atom (such as helium) turns into another, less massive atom (such as hydrogen) ... what happened to the difference in mass? It turned into energy, the same energy we feel as heat, see as light, and all sorts of other types of electromagnetic radiation. So nuclear fusion, which involves the converting of mass to energy, is what ultimately provides all energy on Earth. This happens in every star we can see with the naked eye, and (of course) quite a huge number of ones we can't see with our eyes.