Cosmologists say the expansion of the universe is accelerating, what is driving this?
The short answer is ‘Dark Energy’, but then the obvious next question is “what’s dark energy”? It’s named that basically because we know very little about it. We can observe that the Universe is expanding by measuring the speeds of distant galaxies; we find that all are receding from us, and that the further away they are the faster they are receding. In addition, by looking at the nearby universe Astronomers have managed to determine that the universe recently (a few billion years ago) entered an era of accelerating expansion. This acceleration must require an energy source, and we call it dark energy.
One idea is that dark energy might be associated with the vacuum energy of free space. Due to quantum mechanical fluctuations (a whole other topic) even completely empty space has a non-zero energy associated with it. This being the driving force would make sense because as space expands you get more empty space so the dark energy driving expansion would increase, leading to accelerating expansion. However, attempts to connect the two have thus far been unsuccessful. This may well be because currently there is no theory of quantum gravity, and Cosmology is fundamentally about gravity, and the vacuum energy (probably source of dark energy) is fundamentally a quantum effect.
Get More 'Curious?' with Our New PODCAST:
- Podcast? Subscribe? Tell me about the Ask an Astronomer Podcast
- Subscribe to our Podcast | Listen to our current Episode
- Cool! But I can't now. Send me a quick reminder now for later.
How to ask a question:
If you have a follow-up question concerning the above subject, submit it here. If you have a question about another area of astronomy, find the topic you're interested in from the archive on our site menu, or go here for help.Table 'curious.Referrers' doesn't existTable 'curious.Referrers' doesn't exist
This page has been accessed 4293 times since August 14, 2012.
Last modified: August 14, 2012 6:05:31 PM
Ask an Astronomer is hosted by the Astronomy Department at Cornell University and is produced with PHP and MySQL.
Warning: Your browser is misbehaving! This page might look ugly. (Details)