Brian Greene explains Superstring Theory at TED

In 2005 Brian Greene explained superstring theory to the TED audience in laymen’s terms in a very engaging presentation.

Three years ago the Hadron collider at CERN, which has one if its goals to confirm string theory, was still a few year away from completion. But now we are nearly there. Interestingly the public is taking notice now as voices have been raised that this machine might be dangerous. Loud voices actually, so that the CERN website for the LHC (Large Hadron Collider) has to address these concerns and dispel them…

TGVs and mosquitoes

The total energy in each beam of protons in the LHC is equivalent to a 400 tonne train (like the French TGV) travelling at 150 km/h. However, only an infinitesimal part of this energy is released in each particle collision – roughly equivalent to the energy of a dozen flying mosquitoes. In fact, whenever you try to swat a mosquito by clapping your hands together, you create a collision energy much higher than the protons inside the LHC. The LHC’s speciality is its impressive ability to concentrate this collision energy into a minuscule area on a subatomic scale. But even this capability is just a pale shadow of what Nature achieves routinely in cosmic-ray collisions.

During part of its operation, the LHC will collide beams of lead nuclei, which have a greater collision energy, equivalent to just over a thousand mosquitoes. However, this will be much more spread out than the energy produced in the proton collisions, and also presents no risk.

Microscopic black holes will not eat you…

Massive black holes are created in the Universe by the collapse of massive stars, which contain enormous amounts of gravitational energy that pulls in surrounding matter. The gravitational pull of a black hole is related to the amount of matter or energy it contains – the less there is, the weaker the pull. Some physicists suggest that microscopic black holes could be produced in the collisions at the LHC. However, these would only be created with the energies of the colliding particles (equivalent to the energies of mosquitoes), so no microscopic black holes produced inside the LHC could generate a strong enough gravitational force to pull in surrounding matter.

If the LHC can produce microscopic black holes, cosmic rays of much higher energies would already have produced many more. Since the Earth is still here, there is no reason to believe that collisions inside the LHC are harmful.

By all probability these concerns are in the same category as the fears that people would die when going more than 50 miles an hour on this devil’s machine called train. But there have been experiments in the past that seemed rather harmless and turned out to be deadly. I am thinking of Pierre and Marie Curie,
who discovered radioactivity. They did not know that this new phenomenon they had discovered was poisoning them during their work and I remember the anecdote of demonstrating their discovery to friends at a party by circulating a vial with this new substance which you could see with your eyes closed.

So, there is a chance that this microscopic black hole that might be created by the LHC does indeed attract matter and energy from its surrounding, grows and swallows the universe as we know it.

I am actually sure that this will happen, at least in a number of parallel worlds. These parallel worlds are, as far as I know, also postulated by string theory, so we are really approaching the unified theory of life, the universe and everything, a theory that contains its own annihilation – cool!

I have worked at CERN for a little bit, being involved with the old myon-neutrino experiments and I have to admit that it would be a fascinating experience to be at CERN for the first activation of the LHC. I imagine a scene similar to the setting in Douglas Adam’s ‘Restaurant at the End of the Universe‘ – everybody is seated in an exquisite restaurant expecting a great show watching the universe to end.

And, you know what – in one of the parallel worlds according to the string theory to be tested – that will be so!