Cross-posted with permission of OUPblog.
Vlatko Vedral is at the University of Oxford and the Centre for Quantum Technologies, National University of Singapore. His popular book “Decoding Reality: The Universe as Quantum Information” (recently reprinted in paperback by Oxford University Press) discusses many aspects of the relationship between information, thermodynamics and physics.
Every time physicists face experiments that cannot be explained with the existing theories they have to decide which aspects of these theories to keep and which to throw away. Planck, when faced with the inability of classical physics to explain black body radiation, decided to keep the laws of thermodynamics, but threw away the assumption that energy is continuous (which is an integral part of Newtonian mechanics). Similarly, Einstein, when trying to explain the inability of the Michelson and Morley experiments to detect Earth’s motion through the ether, kept the Newtonian assumption that the laws of physics should be the same in all reference frames, but he also introduced the invariance of the speed of light in different reference frames (a fact that is naturally encoded into Maxwell’s theory of electro-magnetism, but not Newtonian physics).
A couple of years ago I published a book called Decoding Reality, in which I argued that the most fundamental units of reality are not energy or matter, but bits of information. I also claimed that this resolves the age old issue of creation ex nihilo, namely how something can be created out of nothing. The answer, I maintained, was in the fact that the bits of information making up the universe are quantum. Quantum physics is based on the idea that information can be created completely spontaneously, namely without any preexisting information.
Science progresses in abrupt jumps, and every once in a while a new theory gets discovered that forces a radical departure from previously held views. I indeed viewed the evolution of science, through what the philosopher Karl Popper called the process of “conjectures and refutations,” as another instance of information processing. But if it’s not unlikely that quantum physics will one day be surpassed, then what confidence should you have in my main thesis? Could it be that the new theory will claim that some other entity – and not a bit of information – is yet more fundamental? In other words, will the post-quantum reality be made up of some other stuff?
I believe that the answer to this question is ‘no’.
For a start, quantum physics is really well established. It’s had about 100 years of complete success as far as experiments. In fact, quantum physics is so accurate that we physicists are getting desperate (let’s be honest here: we’d love it to fail, since this opens the door to discovering a new theory, and for a physicist this is the easiest way of entering the Physics Hall of Fame). Even the weirdest of quantum predictions (what Einstein termed “spooky action at a distance”) are now established beyond reasonable doubt. Quantum objects seem to know about each other in a way not allowed in the classical world, and even when these objects are far apart they act as an inseparable whole.
The fact that quantum spookiness is so well established means that if the new theory comes along, it cannot imply that the world is less spooky than quantumly. The post-quantum world can only be even spookier!
Now, people are studying all sorts of post-quantum scenarios theoretically (it’s good to do this kind of stuff since one never knows where a breakthrough will come from – these are the “unknown unknowns”). And it so happens that they all have to maintain the same degree of genuine randomness as quantum physics. It is not easy to see this — not because the arguments are intrinsically difficult, but because they are lengthy.
The random creation of information, according to the above logic, will remain in post-quantum physics and therefore, bits of information will still be in the best position of explaining the creation of everything out of nothing.
Interestingly enough, some other ideas also survive the onslaught of post-quantum physics. I have studied this recently with my colleagues Markus Mueller of Perimeter Institute and Oscar Dahlsten of Singapore. We have found that the link between information and disorder (as quantified by the infamous entropy) remains in the new theories. This implies, for instance, that the link between the black hole entropy and its area (quantified by the famous Bekenstein-Hawking formula) is also likely to continue to be true.
So, are any predictions in my book going to be wrong if quantum physics fails? Yes, and possibly many. One of them is that I argued for developing quantum technology – quantum computers – and described its advantages over the present technology. If quantum physics fails, then we have to construct technology based on the new physics (but this is good news, since this can only be even more powerful). Likewise, I argued that living systems might be using quantum physics to process information more efficiently. This too fails in the post-quantum world, which again is likely to be good news, but it might also bring a new twist on the relationship between physics and biology. Could it be, as one of the pioneers of quantum physics Erwin Schroedinger alluded a long time ago, that biology will force us to come up with new laws of physics?
We are all busy thinking that a new theory will come by studying quantum physics and gravity and that we need to probe smaller and smaller regions of space and time to get there. But, maybe in order to explain the existence of life we need to come up with another theory of physics – something going well beyond quantum physics.
Want to hear more from Vlatko Vedral, then check out his FQXi blog post, Two predictions for the Post-Quantum World.