card
176

General Theory
of Relativity

OLogy Series
physics
card
176

General Theory
of Relativity

OLogy Series
physics

What would happen if you were to place a bowling ball on top of a nice fluffy pillow? The mass of the bowling ball would cause the pillow to bend or sink. Space bends the same way. Space surrounds everything -- the planets, stars, and even you! Einstein's General Theory of Relativity proved that when an object has mass, it bends the space around it. You are bending space right now!

The 1919 Solar Eclipse
In 1919, Arthur Eddington and a solar eclipse made Einstein the world's most famous scientist -- and changed our understanding of the Universe. At the time, the world still accepted the laws of the Universe proposed by Isaac Newton in the 17th century. Newton believed space was immovable. Einstein challenged this view with his General Theory of Relativity, stating that space could be warped by gravity bending near massive bodies. Eddington realized that if Einstein's theory was true, then light passing through gravity would follow a curved path. In other words, if the light of a star passed by a massive body, such as the Sun, it would appear in a different position compared to where it's seen in the night sky. Eddington knew that the 1919 eclipse offered a rare opportunity to see starlight around the Sun, which is usually invisible because of the Sun's glare. He led an expedition to West Africa to view the eclipse. Despite cloudy skies, he was able to gather accurate measurements of the star's positions. These measurements supported Einstein's theories and made the German scientist an overnight celebrity.

Comets, meteors, and other objects are attracted to the Sun because:

the space around the Sun is bent

the Sun is the most popular place to be seen in

they're chilly and need to be warmed by the Sun's rays

Are you right?

### Correct!

Objects that pass in the Sun's path are pulled toward it because the Sun causes the space around it to bend -- just like a marble would roll toward a bowling ball on a trampoline.

Objects that have smaller masses are pulled toward ones with larger masses because:

objects with more mass are sticky

smaller masses have less magnetic force

objects with larger masses bend the space around them

Are you right?

### Correct!

The more mass that an object has, the more it will cause the space around the object to bend. This bending causes objects with less mass to move toward ones that have more mass.

General relativity is an extension of Newton's law of gravity.

or
?

### Fact

Newton described gravity as a force. Albert Einstein described gravity as a result of mass bending space.

The observations made during the 1919 solar eclipse made Einstein famous around the world.

or
?

### Fact

During a 1919 solar eclipse, Einstein's General Theory of Relativity was confirmed. It showed that light rays from distant stars were deflected by the Sun's gravity.

General Theory of Relativity
Discovered by: Albert Einstein
What it means: any object that has mass causes the space around it to bend
Proven by: Sir Arthur Eddington
When proved: in 1919 during the solar eclipse seen on Principe Island (Africa)

Image credits: Eric Hamilton.