Monday, March 21, 2005

Dark Energy?

I've heard talk of dark energy recently in various tech podcasts and web pages. One of the speakers in the Dark Energy article from the 'In Our Time' podcast disliked the name 'dark energy' and tried to show that it was just Einstein's cosmological constant with a different value. His argument was that 'dark energy' sounds like 'dark matter'. Dark matter is just plain old matter that doesn't produce light (the Earth is dark matter, the sun is
not). Dark energy is not 'opposite' energy, because the concept can't be turned that way. Rather, he sees it as another force to oppose gravity.

The problem is that the universe is expanding at an accelerating rate. The previous thought was that expansion would slow down and eventually compress in a 'big crunch', which might start another 'big bang' (my personal opinion). However, nothing can explain it expanding faster and faster--it doesn't match any conceptual models we currently use in our daily lives. The only way for something to accelerate is if a force continually acts upon the object. Gravity works on energy as well as mass so it can't be either of these.

Gravity is the only known atomic force that has any influence beyond the molecular level. Its nature is still not completely understood, although it can be calculated. There is something that is working against gravity that is causing the accelerated expansion of the universe. The force of the 'big bang' should have given particles an initial velocity but it should not continue to act upon the particles after the event.

More ramblings to come on this.

1 comment:

Anonymous said...

that really IS an interesting note! :)