Understanding Atoms and Astronomical Distances

When we were talking about the atoms, one of the trouble

that people have with the

atoms is that they're so tiny, and it's so hard to imagine the scale

that, uh, the size of the atoms are in size

compared to an apple is the same scale as an apple

is to the size

of the Earth. And that's a kind of a hard thing to take.

And you have to go through all these things all the time, and people find these

numbers inconceivable, and I do, too.

And the only thing you do is you just change your scale.

I mean, you're just thinking of small balls,

but you don't try to think of exactly

how small they are too often or you get kind of a bit nutty,

all right? But in astronomy, you have the same thing in

reverse because the distances to these stars are so enormous.

You know that light

goes so fast that it only takes a few seconds to go to the moon and back, or it

goes around the Earth seven and a half times in a second.

And it goes for a year, two years, three years before it gets to the nearest

other

star that there is to us.

But all our stars are in... The stars that are nearby in a great

galaxy, a, a big mass of stars, which is called a galaxy, a

group. But this ga-- our galaxy is... What is it?

Something a hundred thousand light years.

Like a hundred thousand years

, and then there's another patch of stars.

It takes a million years for the light to get here going at this enormous

rate. And y- you just go crazy trying to make too

real that distance. You have to do everything in proportion.

It's easy to say the galaxies are little patches of stars,

and they're ten times as

far apart as they are big. So that's an easy picture.

It only gets it... But you just go to a different scale.

That's easier.

Once in a while, you try to come back to Earth scale to

discuss the

galaxies, but it's kind of hard. The number of stars that

we see at night is about only about five thousand.

But the number of stars in our galaxy, or the telescopes have shown when you

improve the instrument, oh,

we look at a galaxy. We look at the stars.

All the light that we see, the little tiny and influence spreads from

the star

over this enormous distance of what, three light years for the nearest star.

On, on, on, this light from the star is spreading.

The wave fronts are getting wider and wider, weaker and weaker, weaker

and weaker

out into all of space. And finally, the tiny fraction of it comes in one

square, an eighth of an inch, tiny little black hole, and does something

to me so I know it's there.