- Starting in the 1970s and 1980s,
a lot of physicists became very optimistic
that we're pretty close to finding a theory of everything
that would explain all the interactions
in nature in one coherent whole.
And string theory was one
of the biggest candidates for this.
And partly in response to this overoptimism,
John Horgan wrote "The End of Science"
where he picked up several disciplines of science
and tries to argue
that actually, we're pretty close to the end.
And I have to admit that it's a very good question to ask.
You could have the perspective
that there is a certain period in the history
of mankind where we make those big fundamental discoveries
in nature, and it's just behind us.
It's not going to happen
that we'll discover another continent.
And it's a good question to ask.
Like, is the same the case with science?
Have we just discovered all the big things
that there are to discover?
And Horgan is not saying that we'll stop doing science
or we'll stop doing research
but he's saying that there'll be no new big discoveries.
We'll just add some bits and pieces
to the stuff we already have.
And as someone who has worked
in the foundations of physics,
I have to totally disagree with him on his perspective
on being close to a theory of everything.
And I guess this also puts me in disagreement
with a lot of my colleagues
in the foundations of physicists.
A theory of everything in the foundations of physics
is a theory that combines
all the fundamental forces of nature.
We currently know four of those forces.
That's the electromagnetic force,
which pretty much everyone has heard of.
Then there's the strong and the weak nuclear force.
A strong nuclear force holds together the particles
that make up atomic nuclei,
and the weak nuclear force is responsible
for nuclear decay.
Those are all quantum theories.
And then we have gravity.
This is the fourth force.
And it's not a quantum theory.
And this is kind of the problem.
It's kind of the weird outlier.
And a theory of everything
would combine all those four forces
into one coherent whole.
And I think we're nowhere close to such a theory.
One of the reasons is that we still don't have a theory
for quantum gravity
that would combine the standard model with particle physics.
And yes, string theory was a contender for this.
But it's fallen out of favor.
It's not even clear that'd actually solve the problem
it was meant to solve in the first place.
And pretty much the same thing could be said
about other approaches to quantum gravity.
So this thing is still unsolved.
But maybe even more importantly,
we have a much bigger problem in the foundations of physics,
which is the measurement process in quantum mechanics.
It's created some practical problems
in how we analyze experiments.
Physicists are just confused about what exactly it means,
that we have to do this measurement update.
Exactly what is the measurement?
What does it take to do a measurement?
We don't know.
The theory can't answer this question.
And I think that an answer is needed.
And indeed, when we find this answer,
it'll lead to a lot of progress.
And it's not just progress in our theoretical understanding,
it's also progress by way of new technology
because if you look at all the technological devices
that we use today, they're all based
on quantum mechanics.
So if we manage to improve this theory of quantum mechanics
by eventually understanding how a measurement process works,
I think this will also help us
to improve our technological gadgets,
and it'll have a huge impact on the entire world.
So I don't think we're anywhere close to the end of science.
Now, I'm actually quite optimistic
that we'll be able to solve the measurement problem
in quantum mechanics within the next one
to two decades or so
because it falls into an area,
quantum technologies and quantum computing,
quantum information, quantum optics
where there is a lot of technological progress
at the moment.
So sooner or later, they'll just stumble over something new,
something that they can't explain,
and then they will call for the theorists
to please explain this.
And this is when a lot of progress
is going to happen very suddenly.