DR_Everything and nothing: The amazing science of empty space Flashcards
Imagine that our Sun is the size of a grain of sand on a beach. One Sun is one star in the Milky Way among over 200 Billion stars. Our Sun is like one grain of sand on entire beach. Milky Way is one of 100 Billion galaxies in the observable universe.
It is estimated there are more stars in the Universe than all the grains of sand on every beach in the World!//Diameter of Earth’s orbit is 180,000,000 miles.//In the 1920’s, we thought the entire Universe was the Milky Way alone! We had no idea of other galaxies!//Edwin Hubble made the discovery of other galaxies in 1923. He discovered Andromeda Galaxy. This is our closest Galaxy.//It is 2.5 Million light years away!The light we see now started its journey before modern humans had evolved. [think about that a second. Ghost stars] //As we see Andromeda, we are seeing the photons that left it 2.5 million years ago.//Photon: Noun. A tiny particle of light or electromagnetic radiation.//Andromeda has over a Trillion stars.
Einstein.//Does space have a form? We are always trapped in the three dimensional view. To understand the form of space, you need to think in four dimensions.//Einsteins discovered it, the 4 D of Space. This is space on Earth as well as space in spacetime. Like the space from you to the wall. Space is dynamic!//We do not live in a flat world. We live in curved worlds, hence the general theory of relativity.
Relativity. Noun. To observe anything other than light moving through time and space, depends on the position and movement of someone who is watching. Example: People riding in a train. To them the people outside the train are flashing by very fast. To the people standing outside the train, the people in the train are flashing by very fast. To the people in the train, looking as other train passengers, everybody is sitting sit and not moving.
The space around us isn’t flat, it is curved. Space is bent and warped all around us. It is flexible and changes it geometry, which gives rise to the force we call gravity.I
n Newton’s time, gravity was thought to pull all objects together. But Einstein gave us a “new perspective”.
Although gravity appears to be a force, it is nothing more than the curature of space itself.
When an object falls, it’s not being pulled, by gravity at all. It’s just following the simplest path through bent space. [almost an illusion if you will because it looks like gravity is pulling the object to the floor]
[REM space is dynamic]
It is the presence of Mass that causes space to curve and distort. The reason we have gravity on Earth is because the Earth’s mass is bending space around it. [MN: Just like water bends around our body in the pool.]
The Universe is an expanding entity. [see note A] Eventually all the observable Universe will be the Milky way, just like it was prior to 1923. Future generations will never see the distant galaxies because the space has increased between us and them.
Note A: The stars are not moving away from us, it is just the space between them is expanding. Kind of like a hundred wooden boxes in the ocean drifting apart. The space between them is expanding.
Note: Our daytime skies are blue because the direct beams of light from the Sun are being compressed. This compression of electromagnetic radiation makes our brains see the sky as blue. Upon Sun rise and Sun set, we are only getting indirect beams from the sun, so the beams we see are not as compressed and our brain sees them as red. Thus the red sky at morning and at sunset. [kind of like hearing a different radio frequency. Each frequency wave height and length would sound different]
