Philosophy of cosmology

Images are now being taken on the world's most powerful digital camera. For over 500 nights over the next five years the Dark Energy Camera will photograph the light from more than 100,000 galaxies up to 8 billion light-years away in each image.

Cosmologists gathered in the Netherlands last week to discuss a new view of the Universe. The Universe as seen by Planck was an international conference to discuss the recently released scientific results from the Planck satellite, including two particularly striking snapshots of the early Universe.

Some of the things I overheard at Stephen Hawking's 70th birthday conference did make me wonder whether I hadn't got the wrong building and stumbled in on a sci-fi convention. "The state of the multiverse". "The Universe is simple but strange". "The future for intelligent life is potentially infinite". And — excuse me — "the Big Bang was just the decay of our parent vacuum"?!

This is the first part of the lecture given by Astronomer Royal Martin Rees at Stephen Hawking's birthday symposium.

This is the second part of the lecture given by Astronomer Royal Martin Rees at Stephen Hawking's birthday symposium.

This is an excerpt from Stephen Hawking's address to his 70th birthday symposium which took place on 8th January 2011 in Cambridge.

Experiment discovers evidence for dark matter

We're all on a journey into the future, but can we travel into the past? Find out with Kip Thorne

And what are gravitational waves?

What's the mysterious stuff that makes up 70% of our Universe?

With online socialising and alternative realities like Second Life it may seem as if reality has become a whole lot bigger over the last few years. In one branch of theoretical physics, though, things seem to be going the other way. String theorists have been developing the idea that the space and time we inhabit, including ourselves, might be nothing more than an illusion, a hologram conjured up by a reality which lacks a crucial feature of the world as we perceive it: the third dimension. Plus talks to Juan Maldacena to find out more.

The mathematical maps in theoretical physics have been highly successful in guiding our understanding of the universe at the largest and smallest scales. Linking these two scales together is one of the golden goals of theoretical physics. But, at the very edges of our understanding of these fields, one of the most controversial areas of physics lies where these maps merge: the cosmological constant problem.