Quantum mechanics and general relativity are two crucial ideas we have to explain the universe around us. They are among the finest ideas ever created by the human race, but unfortunately they refuse to work together.
The limits of the two theories are under constant investigation. Scientists hope to find clues of the next big theory there, the one to bridge the chasm between quantum mechanics and relativity. The most discussed and debated idea is string theory but others are also being investigated.
Researchers now report a quantum gravity theory that appears to be successful in explaining what we currently see in the universe, and it works in explaining processes that require both quantum mechanics and relativity, such as black holes. The approach is reported in Physical Review Letters with the title “Finite Quantum Gravity Amplitudes: No Strings Attached.”
A crucial aspect of the theory for the researchers is that it is founded on previously tested concepts. We have no evidence that the strings proposed in string theory exist. To find them, we would need particle accelerators significantly more powerful than the Large Hadron Collider (LHC) at CERN. Quantum gravity theories don’t require strings acting as particles, they just assume particles are there.
“For scientists, this alternate theory is attractive to use because it has been extremely difficult to connect string theory to experiments. Our idea uses the physical principles that are already tested experimentally. In other words: nobody ever observed strings in experiments, but particles are things that people definitely see at LHC experiments. This lets us bridge the gap between theoretical predictions and experiments more easily,” co-author professor Frank Saueressig, from Radboud University in the Netherlands, said in a statement.
The work is an important foundation for this theory but what is crucial is creating predictions about the universe. A theory can be beautiful and explain everything we see, but it also needs to be able to predict what we are yet to see and explain it in a coherent framework.
The team will now apply their new theoretical framework to black holes, trying to understand the implications of this theory for those cosmic conundrums.
“After all, there is only one set of laws of nature and this set should be able to apply to all kinds of questions including what happens when we collide particles at fantastically high energies or what happens when particles fall into a black hole,” Saueressig added. “It would be fantastic to demonstrate that there is actually a link between these seemingly disconnected questions which allows to resolve the puzzles appearing at both sides.”