Name: 【TED-Ed】Dark matter: The matter we can't see - James Gillies
Uploaded: 2013-05-13T08:30:09.000Z
Duration: 5 min 35 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

all you needed to make it were four elements:

the four basic elements in different ways,

you could produce all the wonderful diversity of the universe.

It didn't predict anything that could be measured,

and measurement is the basis of experimental science.

But the Greeks were great scientists of the mind

with one of the most enduring scientific ideas ever.

of tiny, indivisible bits of stuff called atoms.

over the earth, air, fire, and water theory

Centuries of scientific thought and experimentation

In Leucippus's theory, the atom is the smallest,

indivisible bit of stuff that's still recognizable

The only thing wrong with Leucippus's idea

What appears to be the ordinary stuff of the universe

Leucippus's atoms, and the things they're made of,

Physicists know the rest of the universe,

All the stuff that's made of atoms is visible.

are beautiful, spiral shapes, spinning gracefully through space.

When scientists first measured the motion

and weighed the amount of matter they contained,

They found that there's not enough visible stuff

Later measurements of individual galaxies

There's simply not enough visible stuff in galaxies

to provide enough gravity to hold them together.

and that we're residents of a fairly ordinary planet,

in the spiral arm of a fairly ordinary galaxy.

one step further away from the center of things.

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【TED-Ed】Dark matter: The matter we can't see - James Gillies

stuff

matter

evidence

great