![]() ![]() These would be billions of light years long, thinner than a proton and spectacularly dense. One of string theory’s most dramatic predictions is that we should find cosmic strings. These include looking for gravitational waves and scrutinising the results from particle accelerators.Ĭosmic string: The search continues (subscription only) String theory fights back (subscription only)įaced with accusations that their mathematical models cannot be tested, string theorists are retaliating with a host of thoughts on how to verify their ideas. Those neutrinos may reveal the existence of extra spatial dimensions, which is a key prediction of string theory. The IceCube experiment will be able to detect up to 10 cosmic neutrinos per year. ![]() Ice-bound neutrino hunter may bolster string theoryĪ neutrino experiment at the South Pole may be able to detect the predicted effects of string theory. Sean Carroll argues that, despite the difficulties of testing it, the theory has still given us many valuable results. ![]() Once it’s working properly, the Large Hadron Collider could achieve the energies needed to reveal these effects.ĭespite capturing the popular imagination, string theory is losing its public appeal. Particle collisions could reveal whether some of the fundamental assumptions of string theory are wrong. It could be a problem for string theory – or for inflation. This is well accepted in physics, but it turns out that string theory has trouble producing inflation. In its early days, the universe is thought to have expanded extremely rapidly through a process called “inflation”. Many physicists think this is a weakness of the theory, but Leonard Susskind thinks it could actually help us understand why our universe is so well suited to life. String theory describes 10 500 separate universes, with different constants of nature and even different laws of physics. String theory could lead to multiple universes But these extra dimensions may not be necessary after all – at least, not if a 40-year-old idea called “twistor theory” has anything to do with it. One of the most widely publicised aspects of string theory is its need for extra “tiny” dimensions of space. String theory is the most popular idea for explaining why these four forces exist, but it has some serious competition. Physicists believe that there was only one force just after the big bang, and as the universe cooled, it split into the four forces we now observe. The theory of everything: Are we nearly there yet? (subscription only) Instead, it seems exquisitely tuned to make life possible. Why is our universe the way it is? If some of its fundamental laws were even slightly different, our world would be a strange and lethal place. String theory may predict our universe (subscription only) To accompany this interview, we’ve put together a beginner’s guide to one of physics’ strangest imaginative feats. ![]() This week, we met up with Edward Witten, one of the leading proponents of string theory (see Inside the tangled world of string theory). While these notions are deeply strange, the key issue for string theorists has actually been the difficulty of testing their ideas. ![]()
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