Name: String theory - a simple way to understand the universe | BBC Ideas
Uploaded: 2021-10-07T19:35:31.000Z
Duration: 5 min 42 s
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For as long as humans have looked at the stars,

Scientists have long searched for a simple theory

and so far, every one of them has failed to fully explain

But there is one particularly enticing idea

that some theoretical physicists think might just be 'it',

Other theories do collapse. Other theories do blow up.

grappling with - and attempting to answer -

When Dr Kaku talks about our present-day understanding,

he means our current best theories about the way the universe works.

And sometimes even give conflicting results -

Albert Einstein's general theory of relativity works perfectly well

for predictions about the movements of stars and galaxies,

but doesn't work when applied to the behaviour of subatomic particles.

Conversely, quantum theory is great with atoms

but predicts the whole universe should collapse into a black hole,

which it clearly doesn't because we're all still here!

So, will we ever find a single theory that explains everything?

Two thousand years ago, Pythagoras asked himself that question.

said that there must be a unifying principle,

a paradigm by which to summarise the vast creation

that we see all around us of the universe that we know.

And he looked around and saw a lyra string.

You pluck a lyra string and you get a note,

you pluck another one, you get another note.

And then he said, aha, the mathematics of music is rich enough

to explain the diversity of everything we see around us.

And only recently have we come up with a new idea

So how do we go from Pythagoras' musical musings to proper physics?

The first port of call would be a particle accelerator

like the Large Hadron Collider at CERN in Switzerland,

where tiny particles are smashed to pieces in high energy collisions

These experiments are our best way of testing theories

So what does string theory predict we would see?

We now believe that all these subatomic particles,

that we get by smashing protons at the Large Hadron Collider,

they're nothing but musical notes as Pythagoras believed.

Of course, Dr Kaku doesn't mean an actual rubber band.

Or to put it another way - the strings in string theory.

And just like the strings on a musical instrument,

if you put some energy into them, they vibrate.

It vibrates one way, we call it an electron.

We vibrate it another way, it's called a neutrino.

We vibrate it another way, it's called a quark.

So, string theory offers a tantalising possibility -

an explanation for the vast variety we see in the universe,

from the collisions of stars to the collisions of atoms.

Of course, string theory is just that - a theory.

Its critics point out that many of its predictions are untestable -

could even explain the mystery that is dark matter.

Dark matter makes up most of the matter of the universe.

It is invisible and it holds the galaxies together,

We think that dark matter could be the next octave of the string.

If you could magnify all the particles you see around us,

a lot of rubber bands vibrating at different frequencies.

If Dr Kaku is right, the huge complexity of the entire universe