FROM GROOVY TO FANTASTIC

Bryan Chu – 4th Grade, Foothill Elementary

GRAVITY

We are the frog in the well – trying to figure out what that circular shaped thing is…

Aristotle (384 BC – 322 BC)

Heavy bodiesmove to thecenter ofthe universe bytheir nature,

thegravitas

Galileo (1564 – 1642)

Heavy object and light object hit ground at the same time

Inertia and heaviness “cancel” each other’s effect

Galileo pointed his telescope to the heavens and found 4 objects orbiting around Jupiter, NOT Earth.

He then believed in Copernicus’s heliocentric (i.e. Solar) system.

Newton (1642 – 1727)

Everything attracts each other, on Earth or in the Heavens: Universal Gravitation

Gravity is proportional to the Mass of the two objects, and inverse proportional to the square of the Distance

2

21

R

MMGFg

R=distance

M1=mass of the apple

M2=mass of the Earth

G = Newton’s gravitational constant

Kepler discovered that the planets orbited in ellipses

Because of the planets’ speed, their desire to go straight is stronger than the pull of gravity, causing elliptical orbits

Einstein (1879 – 1955)

Gravity is Mass’s ability to bend space (well, actually space-time)

The apple falls down because the space we live in is curved strongly by the Earth’s mass – i.e. “In a Ditch!”

A 2D Visualization A 3D Visualization

The Big Bang

The Big Bang is an explosion that created the universe

Gravity attracted mass and formed stars, planets, and galaxies

According to the Big Bang theory, this event took place 13.77 billion years ago

The universe expanded from an extremely dense and hot state into what it is now (it is still expanding)

Stars Stars power themselves

by fusion Fusion merges multiple

hydrogen atoms into a helium atom, and generates light that shines on us. This is the normal life of a star. Thanks, Sun.

Hydrogen

Hydrogen

Helium

When a star similar to the size of the sun runs out of hydrogen, it will “die” – its fusion can no longer push out the pull of gravity, and its core collapses and its outer shell swells outward. Eventually its core will collapse into a very dense white dwarf the size of the Earth, and its outer layer becomes (planetary) Nebula. That’s a relatively peaceful “death”.

Oh no! I’m out of

hydrogen!

When a large star or a giant star dies, it is more violent. Because it has a large mass, it has a strong gravity. Its gravity will shrinks the star smaller and smaller which makes gravity stronger and stronger. Eventually its gravity crushes it into a neutron core so dense, small and hot, it explodes into a Supernova. Supernovas are the brightest events in the universe. The remaining mass is a tiny dense object: a neutron star, or, if it has more mass, a Black Hole.

Neutron stars are so dense that it would be like the entire human population compressed into the size of a sugar cube.

Black holes have infinite gravity, and scientists normal formula doesn’t work anymore

The event horizon is the region around the black hole. If an object enters the event horizon, it will never be able to come back.

Black Holes

Wormholes

Wormholes are properties of space- time that would be a shortcut through space- time if we could go through it.

Dark energy is the exact opposite of gravity

Dark energy repels objects instead of attracting them

If dark energy is put in a wormhole, it will repel on all sides of the wormhole, allowing enough time for things to go through it

This is possibly what dark energy might look like if it wasn’t invisible

Higgs Boson

The Higgs Boson is a particle that, along with others, is responsible for all forces in nature except gravity

It is possible that the Higgs Boson is responsible for all the mass in the universe