BBC Horizon 2006: 2/5 Most of Our Universe is Missing

In 1974 the astronomer Vera Rubin, was working on a project investigating stars at the outer edges of galaxies. What she discovered was quite a surprise.

Shortly after the apple fell on his head, Newton famously declared that gravity was 'universal'. An apple falling on Earth obeys the same mathematical rules as an apple falling on the other side of the Universe. In the same way that the Sun controls the orbiting planets by exerting gravity on them, a spiral galaxy must be controlled by the gravity-giving black hole at its centre.

It has long been known that Pluto, at the edge of our solar system, travels much slower than Mercury, close to the Sun. In fact observations like these allowed Newton to pin down his laws in the 17th century. When Vera Rubin did her work on galaxies she expected to find that as you reach the edge of a galaxy the stars would be moving much slower than those close to the centre. But it didn't work out like that at all.

She found that almost all of the stars in spiral galaxies are racing around the centre at approximately the same speed. This was very strange. Could it be that Newton's laws weren't really universal and didn't apply in galaxies?

Questioning Newton seemed unthinkable, so the majority of scientists went down a different route altogether. Rather than variable gravity, they argued, there had to be something else in galaxies, something that was providing extra gravity. With extra gravity, the stars would be pulled harder, and would travel faster -- as Rubin's observations suggested. And the name they gave to this extra stuff? Dark matter.

Category:

Science & Technology

Tags:

• universe
• dark matter
• dark energy
• gravity
• black holes
• astronomy
• multiverse

[beatboxpeej]

Dark Matter is GOD! trolololo

[paarsefrikandel]

i got another one: Dimm gravity or dumb matters hehe, cool docu tho, just kidding around

[josyula547]

THANK U SOOOOOOOOOOOOO MUCH!!!!