Unit 9 - Relativity and Cosmology

What does relativity study?

The relationships between space, time, and events across different frames of reference

What are inertial frames?

Non-accelerating frames where the laws of physics apply equally.

What was the Michelson-Morley experiment trying to detect?

The existence of the aether as a medium for light.

What was the result of the Michelson-Morley experiment?

No aether detected; light's speed is constant in all frames.

What are Einstein's two postulates of special relativity?

1) Physics laws are the same in all inertial frames. 2) Light speed is constant in all inertial frames

What is time dilation?

Moving clocks run slower compared to stationary ones

What is length contraction?

Moving objects appear shorter in the direction of motion

Relativistic momentum formula?

p = gammamv

What is the famous equation for mass-energy equivalence?

E = mc^2

What are nuclear fission and fusion?

Fission splits heavy atoms; fusion combines light atoms to release energy.

How is energy created in nuclear reactions?

Through conversion of mass into energy via E = mc^2

What is matter-antimatter annihilation?

When matter and antimatter collide, they destroy each other and release energy.

What is general relativity?

Einstein's theory explaining gravity as the curvature of spacetime

What causes spacetime to curve?

Mass and energy.

What is gravitational lensing?

The bending of light by massive objects.

What are gravitational waves?

Ripples in spacetime from massive accelerating bodies, confirmed in 2016.

What is the Big Bang theory?

The universe began from a hot, dense state and has been expanding for ~13.8 billion years

What evidence supports the Big Bang?

Expansion (redshift), cosmic background radiation, and elemental abundance.

What is Heat Death?

A scenario where the universe expands forever and reaches thermodynamic equilibrium.

What is the Big Crunch?

A hypothetical collapse of the universe if gravity reverses expansion.

What is the 'flat universe' model?

An expanding universe that slows but never stops; best fit with current data.