General Relativity

1905 Einstein works out theory of relativity

Gravity didn’t work in well with his theory

1911 the happiest thought in his life

“If I jumped of a barn and I was falling, I would cancel gravity”

The principle of equivalence

This is why there is weightlessness, when only gravity is working on you

F=ma (principle of inertia)

qE = ma therefore a = qE/m

F= GMm/R2

Why every object gets the same acceleration is that gravitation principle of equivalence

Rocket ship and things falling, if the floor rises to meet the falling objects

Both gravity and centrifugal forces are not real, they are changes in coordinate systems

The Principle of equivalence is local

If your lab is falling toward the earth,

The lab can’t be too big or falling for too long

As it falls towards the earth, the distance between them get smaller

The size depends on the accuracy of the measuring devices

If they are stacked on each other then they experience tidal acceleration

And they will pull apart as they fall

Tide: Closer to moon, stronger gravity pull

1911-1913 Figures out how to patch all of the situations together

Used Riemannian geometry

Wrote a paper with Grossmon that has Einstein's equation but doesn’t know how to use them yet

But they didn’t figure out coordinate system yet

1915- Hilbert had a great math tutor but Einstein was working on it too

Both of them are trying to find the theory as a race

Now Einstein understood his equations

In solar system, planet's orbit shifts 1.5 degrees each century

There was extra around mercury

Hilbert turned his paper in a day before Einstein

Clock is in rocket ship that sends a beam of light up to the other clock

Low clock + H/C is about = high clock

As the rocket launches, the light still goes at C, but the relative time is

Low clock2 + H/C-gt = high clock2

The clock at the top takes longer to receive than the clock on the bottom sends signal

Simultaneous is relative, you have to specify your coordinate system

Slope of light always bisects space and time

Twins in space

Worked out special relativity and general relativity

Red shift

Mercury

Bending of light (light from distant galaxies get bent/gravitation al lensing and it magnifies)

Time delay

GPS has to take general relativity into account

In understanding of the universe

Dark energy/ Dark Matter

72% Dark energy

23% Dark matter

3% other matter

2% ordinary matter (earth stuff)