Astro Section 3 Flashcards

Question

Will the universe continue to expand forever

Answer 1

It depends on the amount of dark matter. The amount of dark matter is only about 25% of the critical density so the expansion of the universe will overcome its gravitational pull. Actually the expansion is speeding up. This is because of dark energy.

Answer 2

Extremely hot and dense, It has cooled as it expands. The early universe was full of particles and radiation because of its high temperature. Photons converted into particle – antiparticle pairs, And then back to photons again. The four known forces of the universe are: strong force, electromagnetism, weak force, gravity. may have been one super force Because of high-temperature then diverged With time. Also, as the universe cooled, Particle production stopped leaving matter instead of antimatter.

Answer 3

We have leftover radiation, and the Big Bang theory correctly predict the abundance of helium another light elements.

Answer 4

Radiation left over from the Big Bang is now in the form of microwaves , Observable with radio telescopes .The cosmic microwave background (Or radiation left over from the Big Bang) Was discovered by penzais and Wilson in 1965. It has been streaming across the universe freely since Adams were formed @ 3000 k.

Answer 5

Big Bang theory predicts 75% hydrogen, 25% helium by mass because of how protons and neutrons combine.

Answer 6

Where does structure come from?, Why is the Universe so smooth on large scales? Why is the density of the universe so close to critical density? All are answered by inflation.

Answer 7

Structure formed by stretching tiny quantum ripples to an enormous size. These ripples become seeds of dense areas and seeds for all structures of the universe. You deserve global universe became smooth before inflation when it was tiny and then inflation expanded the smooth patch to cover the whole microwave background. Inflation flattened the curvature of space creating a nearly flat universe

Answer 8

If the universe is infinite, unchanging, and everywhere the same, then Stars would cover the night sky and the sky would be Infinitely bright. Why is it dark?

Answer 9

Because the universe changes with time and because we can only see a finite part of the universe. As we look at an space we can look back to a time when there were no stars

Answer 10

First life on earth was bacteria like organisms that lived about 3.8 5 billion years ago. We know they existed because of their fossils and Carbon isotope evidence

Answer 11

2 billion years

Answer 12

Life has devolved through time via natural selection(darwinism). This is supported by the discovery of DNA and that evolution works through mutations of DNA. By mapping relationships scientists have discovered the tree of life, and that all living things come from a common ancestor.

Answer 13

Genetic studies show that earliest life on earth was similar to the bacteria that is found near deep ocean volcanic vents. The Miller Urey experiment shows that the building blocks of life can be formed spontaneously under the conditions of early Earth.

Answer 14

That it landed here on rock from Mars or Venus. Microbes can survive years in space.

Answer 15

Early oceans form, cyanobacteria start releasing oxygen, oxygen begins building up in the atmosphere, Cambrian explosion, dinosaurs and small mammals, early hominids.

Answer 16

I nutrient source, energy, liquid water ( This is the hardest one to find on other planets, He thinks other options are ammonia or methane or a life form that can transport energy through a solid matrix)

Answer 17

NASA rovers found that Mars had liquid water in the past, it still has subsurface ice and possibly subsurface water near sources of volcanic heat. A meteorite found antarctica they thought was from Mars because of its composition and thought it contained fossil evidence of nano bacteria from Mars. Most scientists doubt, Likely contaminated by Earth.

Answer 18

Possibly could be life on Europa, Ganymede, Castillo. Little energy available but maybe enough. Possibly have subsurface water.

Answer 19

Habitable planet world contains the necessities for life as we know it. Constraints are: one – old enough to allow time for evolution. Two – need to have stable orbits. Three - Size of habitable zone, a region in which a planet of the right size could have liquid water on its surface (The bigger the star the bigger the zone). Even with these constraints billions of stars in the Milky Way could potentially have habitable worlds.

Answer 20

Oh your rims of galaxy don't contain enough Heavy elements to make habitable planets, but inner regions are too hostile for life because of supernova. So habitable planets are restricted to a galactic habitable zone as well. So really we don't know yet because we don't understand all the factors to make a planet suitable for life.

Answer 21

Yes the SETI experiments look for deliberate signals from extraterrestrials who want to Contact us. They sent out radio signal to globular cluster M13 in 1974.

Answer 22

Yes. At the speed current spacecraft travel it will take 100,000 years to get to the nearest star. The amount of energy needed is enormous. We need far more efficient engines.

Answer 23

If civilizations are as common as our statistics suggest then the next civilization should be on average a couple hundred light-years away. Why haven't we detected them yet?

Answer 24

One: we are almost alone, life and civilization is rarer than what we think. Two: civilizations are common but interstellar travel is not because it's difficult, they don't have a desire to explore, they destroy themselves before achieving interstellar travel. Three: there is another galactic civilization And perhaps we will meet them someday.... We don't know where they are.

Astro Section 3 Flashcards

(48 cards)