Unsolved mysteries: why is dark energy fine tuned for life?
'God and the Big Bang' #05
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Although scientists are confident in the general picture of the Big Bang, many unsolved mysteries remain. One of these is about the nature and strength of the dark energy which appears to be driving the universe apart. This is fine tuned for life: if it was just a little more than it is, we would not be here.
Not only is its nature a mystery: its strength is also a mystery. Scientists believe it should be about 10120 times more powerful than it is. (Professor Steven Weinberg once called this 'the worst failure of an order-of-magnitude estimate in the history of science.')
Yet if it was much more powerful than it actually is, we couldn’t be here at all. The universe would have expanded too fast for complicated structures like stars, galaxies, and people, to form. This is another example of cosmic fine tuning.
‘The fact that we are just on the knife-edge of existence, if the dark energy were very much bigger we wouldn’t be here, that’s the mystery.’
- Professor Felix Bloch, Stanford University
To try to understand the first tiny moments of the Big Bang, scientists are now theorising about ‘super-symmetry’ and string theories. Some of their ideas predict that we live in a multiverse, made up of billions upon billions of different universes.
At the moment, all these ideas are just speculations. There isn’t any evidence for them. There are some of them, like the multiverse, that we may never be able to test directly.
But within the next decade, the Large Hadron Collider, and new telescopes in space and on the ground, will help us to find out more about Dark Matter and Dark Energy, about strings and supersymmetry.
