I want to write something following the recent announcement of the discovery of gravitational waves. I’m not going to write about that discovery itself, because it’s all over the news. Instead, I want to ponder – what next? And in particular, which science mystery would I most like to be solved before I die?
I’m going to start with Physics, and stick largely to it, because I’m a physicist by training, and I know it best. But some of these questions branch out beyond Physics. Here are the ten big mysteries in science I’d like answers to:
1 What is dark matter?
Dark matter makes up the bulk of the matter in the observable universe. Its existence has been deduced by studying the behavior of distant galaxies, but it hasn’t yet been detected in the laboratory, nor is there any explanation for what it is. That’s embarrassing, frankly. Someone should do something about it, and quickly.
2 What is dark energy?
Dark energy makes up most of the energy in the universe and is causing the rate of expansion of the universe to accelerate. That’s annoying, because already 97% of the observable universe is now forever beyond our reach, even travelling at the speed of light. Thanks, dark energy! But perhaps we could do something useful with dark energy, if we knew what it was.
3 How can Einstein’s description of gravity as a warping of space-time be reconciled with quantum theory?
Einstein’s General Theory of Relativity describes how gravity works. Quantum Field Theory describes how the other fundamental forces of nature work. Frustratingly, these two great theories of the 20th century are fundamentally incompatible with each other. Grrr! That’s frustrating at an intellectual level, and it stops us from understanding situations where gravity and quantum effects are of the same order of magnitude – like inside a black hole, or around the time of the Big Bang. String Theory and Loop Quantum Gravity are two current theories intended to provide a consistent theory of quantum interactions and gravity, but they are both works in progress.
4 What is the explanation of quantum entanglement?
This is the mechanism by which pairs of quantum particles seem to be able to interact instantaneously with each other across arbitrary distances – an effect that Einstein called “spooky action at a distance” and which will drive you nuts if you spend too much time thinking about it.
5 What happened before the Big Bang?
So the Big Bang wasn’t the origin of the universe, but describes a state nearly 14 billion years ago when it was much smaller and much hotter than it is now. The current theory is that before the Big Bang the universe experienced rapid Inflation. But what happened before Inflation, or has the universe always existed?
6 Are we really part of an infinite or semi-infinite multiverse?
Lots of speculative theories in Physics invoke the idea of a multiverse. In quantum theory, the Many Worlds interpretation posits that the universe divides every time a quantum event occurs. That’s not a very economical way to run a universe, in my opinion. String theorists believe that our universe is one of a multitude of possible universes, and that each is equally likely to exist. But that’s just because String Theory sucks. Inflation theory suggests that our universe is just a microscopic bubble in an unimaginably vast sea of universes, and that’s quite probably true.
7 Is faster-than-light travel possible?
My head says no. My heart dreams of travelling to the stars. Faster-than-light (FTL) travel is theoretically highly problematic, because it breaks Einstein’s Theory of Relativity and opens up the door to time travel, which is self-evidently a thoroughly bad idea. But perhaps there are loopholes (or even wormholes) that we could use to travel to other galaxies, or at least to vacation in the Milky Way.
8 Is there intelligent life on other planets?
Statistically, there surely must be. But where? And what is it like? Will we ever meet intelligent aliens? If they exist within our own galaxy, we might meet them one day, but if they exist in other galaxies, then we almost certainly won’t, unless FTL travel is possible. So far, on balance, the evidence is that there isn’t any, otherwise aliens would already be here on Earth.
9 How did life on Earth originate?
Did it start here, or did primitive microbes come from elsewhere? Is simple life common throughout the universe? I feel that it probably is.
10 What is the origin of the laws of Physics?
This is the one I really want an answer to! Tell me now, god-damn-it! But I suspect we’ll have to answer most of the other questions before finding out. What I’m asking here is, how do sub-atomic particles “know” the rules that govern them? And why these rules, not others? I’d give anything to know the answer to that.
What about you? Is there anything you’d like an answer to? Do you want answers at all, or do you prefer the idea of a mystery?