Cosmology astronomy

What was the big bang?

expansion of the universe and the beginning of time and space

When was the big bang?

13.8 billion years ago

Where was the big bang?

Everywhere

What is the cosmic microwave background radiation (CMB)?

Afterglow of the Big Bang, the “surface” of the universe left from when it transitioned from opaque to transparent

Where can the CMB be seen?

All directions at a light travel time of 13.8 Ga

What is the significance of the CMB?

Limits the distance and time visible, which indicates the Universe had a beginning and is expanding

Why is there a limit to how far away in space/back in time we can see and if so, why?

Literal “firewall” where you “see” the “surface” of the Universe is when it wasn’t transparent

Explain the “critical density” for the Universe and the actual density in comparison?

Measurement that compares the expansion of space-time to gravity, current measurements indicate that density of the Universe is equal to the critical density, meaning that the universe is most likely flat but expanding thanks to Dark Energy

How can all of space have the same average ambient temperature?

Quantum effects from before the expansion

Describe flat curved space time: how to tell which universe it is and the consequences of it

Triangles are 180 degrees, universe is at the critical density and expands at linear rate.

Describe positively curved space time: how to tell which universe it is and the consequences of it

triangles are more than 180 degrees and universe is above critical density causing it to slow and then reverse

Describe negatively curved space time: how to tell which universe it is and the consequences of it

triangles are less than 180 degrees and universe is above critical density causing expansion to increasingly increase

Is our Universe static, expanding, or contracting; and how can we tell?

Expanding, Doppler (red) shift

What is dark energy, and how much of the universe does it make up?

Energy responsible for expansion of space time and 68%

Big Crunch

gravity wins or time reverses and everything collapses back to a singularity

Big Rip

dark energy wins, and the expansion of space-time continues to increase at an increasing rate until it affects smaller and smaller distances, until it expands on subatomic scales and rips apart particles

Big Freeze

thermodynamic heat death of the Universe, time/entropy wins and everything fades away as all
useful energy decays until none is left and no further change can ever occur

What is time dilation, and how might it be used to help travel the vast distances of interstellar space?

Consequence of relativity which means that the faster an object travels through space, the slower it will travel through time. A traveler/astronaut traveling near the speed of light will experience less time than a stationary observer, so supplies would last longer

Distance formula

d= velocity x time

time dilation formula

t’=t/y

y(gamma)=

1/√ (1-(v^2/c^2))

What 3 factors are all effected by the Lorentz Factor and how each is altered?

Time dilates, length contracts, and inertia (relativistic mass) increases

What 3 raw materials are required for life?

Liquid water, energy source, and precursor compounds (amino acids,organic compounds)

Where on Earth is life found?

Everywhere

What is an extremophile, and how do they change the search for life?

Organism that lives in an extreme environment, so you might be able to find extraterrestrial life on places that are extreme

Rare Earth Hypothesis

Conditions for life are super specific, so the Earth and its life is unique

Mediocrity Principle

Earth, the Sun, and conditions for life are typical (common), so life should be common too

Anthropic Principle

The conditions for life had to exist on Earth, so whether they’re rare or common they had to happen which means we can’t tell if they’re rare or common

Drake equation

Probability equation that demonstrates that the search for life is likely enough to exceed to be worth undertaking
N=R** fp*ne*fl*fi*fc*L

Fermi Paradox

The Milky Way is big enough and old enough that many civilizations have had enough time to conquer or colonize the entire galaxy, but none are visible

3 possible explanations for why intelligent life might not exist on other planets

We’re first, rare, or doomed

3 possible explanations for why intelligent life could exist but that we cannot detect it

1) They think we’re too primitive or weird to contact

2) There are scary predator civilizations that everyone hides from

3) They all just hangout and play video games instead

Great Filter

development or evolutionary step so difficult that virtually no civilizations make it past

Panspermia

Theory that life can spread from planet to planet through natural/artificial means, thereby transferrin the origins of life to places other than where life is found

Miller-Urey Experiment

Experiment to try to reproduce abiogenesis (the start of life from non-living things) in the lab