No upside to hear, Like a plank plank link?

Yes.

What is the plank length?

Well, first thing to say, but it's very, very small.

Um, physicists tell us that it's the smallest length scale imaginable.

Really.

The subject today is the plank length.

Now this is a length of a plank.

But this is not what a plank length is.

This is about 1.6 meters.

It's the height up to about my nose.

So that's 1.6 meters on.

I want to talk about something which is a bit small.

Well, a lot.

Well, I can't give you an idea of how much smaller jizz suppose I take this length and I chop it into 10 equal sections.

And now that I take this 10th and I divide that up into 10 123456789 10.

And then I take this small piece here.

I can't show you any more because it's going to be a tiny little sliver down there that's chopping it three times.

In order to get down to the plank length, I have to chop this 35 times.

That is due this process off contracting by a factor of 10 35 times.

So it goes down to 1.6 10 to the minus 35 meters on unimaginably small quantity.

You can see this length coming down to that that you can visualize.

But seeing it done 10 toe 35 times is ridiculous.

This is a length which is smaller than the size of a proton by a factor off 10 to the power 20 me.

Write it down.

You have to have to do all these 35 with 123456 and 89 10 and so on.

And 35 of those heroes.

Now I'm gonna write this number down so you could see how ridiculously small it is.

Not no point.

No, no, no, no, no.

At B five zeros, it's that with another five on that with another five.

And if I stop there, that will be 10 to the minus 15 meters, which is about the size of a proton.

The smallest thing that people would more or less visualize.

Oh, no, you can't visualize it.

We're going to carry on 1234 and that's 10 to the minus.

20.

No, no, no law.

But I can't work it out.

I'm gonna have this plus another winter minus 15.

I feel so ridiculous doing all this, but there it is, down there with this extra four sets of zeros with the one on the end.

That's the distance, and then it's won six, so in meat.

So this is the plank length it's arrived at by taking three fundamental constants.

Planks constant, the gravitational constant Big G on the speed of light.

Now Plank was the first person to come up with this length because he just invented quantum physics by studying black body radiation history.

It's quite strange because back in the 18 eighties, backs Plank and others were thinking about the heat energy that was heated light and she was coming out of hot bodies.

In the course of that, he started getting a feeling for that.

There was something quantum mechanical happening from that.

He came up with an idea of fundamental units, so mass length of time in the unit of length is called the plank links.

So the plank length is telling you that when you try to merge the fields off gravity through Newtonian constant Big G with the velocity of light, which is something comes.

It comes in electromagnetism with quantum mechanics.

Emerge them altogether.

Out of it comes somehow unnatural length called the plank.

Length is just right down the three Constance.

Then here's planks constant H, or is it sometimes written h upon to pie, which we could signify like this?

This is big G, the gravitational constant that tells us why gravity is a strong as it is why the Earth has got its strength of gravity on the surface.

Or course big cheated on the mass of the Earth determines the orbiting the moon around the earth, and then the other constant is See Now the curious thing is, if you multiply each bar on G on, then divide by C Cube Cube.

See that gives you the square of the length or, if you like, an area, and that's called the plank length.

So the plank length if we no take square roots, I want the length itself.

We take the square root of that quantity, and that thing gives me the plank length on.

If you want to talk about the early stage of the universe, the period before that, it expanded to the plank length.

We have no idea of the laws of physics, because to do that, we'd have to have a quantum theory of gravity on.

None exist well, if they exist, they exist in a full, but nobody knows where the right or not?

No.

What does it all mean physically?

Well, of course, this is this one, it's telling us is that perhaps if we take quantum mechanics and gravity into account space itself is not really properly defined on length scales smaller than the plank length.

Maybe space time gets foamy is, they say, on these sorts of length scales and then all the particle physics guys.

These cosmologists start worrying about their ideas of bubble universes springing out out of the plank length.

But you better go and talk to a cosmologist or if you get a black hole, for example, if I fell into a black hole, I will be spaghetti, for I turned into long strands of thing and disappear.

But as I go into the black hole, all the entropy associating with me, my complete disorder, how my hair is entirely everything about that would be dissolved in the black hole and in order for the laws of thermodynamics, toe hold.

But the entropy of the universe must increase.

And if the black hole is part of the universe, the total entry must increase in the black hole must have an entropy on.

The person who wrote down the formula for the black hole's entropy originally was beckon Stein and then Stephen Hawking on, he wrote Down the entropy is equal to bolts mons constant times the area of the black hole divided by four times the plank ling squared.

So there it comes in in this model off the interview of a black hole on that is believed by most theoreticians, despite the lack of any evidence to be the entry of a black hole.

So there is a practical use for this flight.