How fast is the universe expanding?

Somwhere around 50 to 100 km/s/Mpc and accelerating....

 

Or maybe we are shrinking at the same rate and everything appears to be getting farther apart? Or is it further?

71 +4/-3 km/s/Mpc (see this thread), and it will expand forever.

Originally posted by fafalone

and it will expand forever.

 

Current models suggest it will.

 

Don't state that with such certainty.

What makes you so sure that the universe will expand forever?

Per the WMAP results provided by FAFALONE: the universe is made up of 73% dark energy, 23% dark matter, and 4% visible matter.

 

Where did all the dark energy come from? Is it possible that the annihilation of matter/anitmatter collisons produces this dark matter at the first moment of the universe?

 

Also, what is dark matter? Is it actual particles and matter that does not luminesce or is it regular matter that is just hard to see with current technology like small planetary bodies and gas clouds?

:confused:

Dark Matter is matter than only interacts through gravity (ie you can't see it by trying to look for it).

 

It's like the invisable man; you can't see it, but you know it's there because of the effect it has on other things.

 

The other things being in this case the rotation of the galaxy; under current models, the galaxy has too little mass to be spinning the way it does, so it's theorised that there is some that we can't see.

mrl_jakiri i have only been on here for a day but u do not cease to amaze me btw how old is everyone on here

I'm 19

Physics5000 said in post #5 :

What makes you so sure that the universe will expand forever?

 

The estimated mass of the universe combined with how fast it is currently expanding/accelerating.

The theory that there will not be enough gravity to slow the expansion down and bring it all back to a single point is on solid ground, with about as much credibility as the big bang theory... but no it's not absolutely certain.

the reason the universe could expand forever is because there is not enough gravity to pull it back together, it may slow down, but then again the gravity issue comes back. the only way the universe will stop expanding is if gravity takes place which it most likly wont because we are expanding to fast for it to stop

It may well expand forever. But mankind and and life in general will have its real problem when the 2nd law of thermodynamics is apllied. There's enough shit in the world at the moment. The 2nd law says things can only get worse. Boo Hoo! I was gonna take a well deserved holiday in the next 10billion years.

The heat death of the universe isn't likely to happen that quickly, but yeah, it's going to all end in nothingness.

ya it wont matter once the sun goes big, i forgot what it was called, it will expand and mars will be the closest planet, so good bye earth if we are even alive by then...

Hopefully by the time heat death is upon us, we'll be walking among the galaxies and be able to do something about it. Assuming that happens. But by the time the sun goes nova, I firmly believe we'll have moved beyond this solar system.

 

In 1000 years, we've gone from chariots to space shuttles... imagine where we'll be in 10,000 years... much less in millions of years when it happens.

It's the red giant phase he's talking about.

 

ps.

 

Faf: you can ignore the first 850 of those 1000 years. Horse driven carts to, say, (in the near future), maglev trains, and nothing to flight...

 

Although personally I'd go back 350 years, to Newton.

We could also go back about 125 years, to the first car. Less than 100 years later, we went from the first cars to space shuttles.

What about the first jet? Let's see, mid 1940s to mid 1960s and we go from the speed of sound to launching into space at well over a mile per second...

 

That's 20 years compared to the 60 million years that humans have existed (I think that's the number). Whoo, that's a big leap...

..and it will expand forever.

 

"But in fact the cosmological constant has nothing whatsoever to do with matter. It is a springiness inherent in space itself, an outward pressure that grows as space expands. The more space there is, the springier it becomes."

 

-One Universe, Neil deGrasse Tyson @ National Academy Press (Science, Engineering and Medicine), copyright 2,000.

 

Far from having an interest in contradiction (re: endless expansion caused by rate of expansion overcoming gravity/combined presence of matter in the universe), I simply wish to state the inspiring nature of what we don't yet know about astrophysics, yet infer through our observations.

As much as any other, we are ourselves born into exciting times...