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HDSO Astronomy > Galaxies & Theories > Flashcards

Galaxies & Theories Flashcards

1
Q

What are the 4 fundamental forces from strongest to weakest?

A
  1. Strong Nuclear Force
  2. Electromagnetic Force
  3. Weak Nuclear Force
  4. Gravity
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2
Q

Explain the Strong Nuclear Force.

A

Attractive force between nucleons (protons & neutrons) that keeps each atomic nucleus together.
Range: approximately 10 to the -15m which is about the size of the largest atom.

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3
Q

Explain the Electromagnetic Force.

A

Attractive and repulsive force involving electric charges and their associated magnetic fields. These are the everyday pushes and pulls.
Range = potentially infinite.

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4
Q

Explain the Weak Nuclear Force

A

Can change quarks. Quarks make up hadrons such as protons and neutrons. Protons and neutrons have 3 quarks. The weak nuclear force can change neutrons to protons and vice versa causing radioactive decay.
Range = 10 to the negative 18m

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5
Q

Explain gravity (as a force)

A

Weakest force. Attractive force, warping of space-time. Involves particles receiving mass from interactions with the Higgs Field.
Range = potentially infinite.

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6
Q

Difference between Population 1 and Population 2 stars.

A

Population 1 are richer in heavier elements - formed in the middle
Population 2- Halo stars and globular clusters, form in outer regions, some metal content

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7
Q

What are the three types of galaxies?

A

Elliptical, Spiral and Irregular.

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8
Q

Explain irregular galaxies:

A 
Smaller
Highly irregular in shape
Rich in gas and dust
1% - 25% the mass of our galaxy
Low luminosity 
Hard to detect
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9
Q

Explain Elliptical Galaxies:

A

Small mass (few hundred stars) to enormous “titans” (trillions of stars)
No disk or arms
Little or no gas or dust
Older population 2 stars
60% of galaxies are elliptical.
Greatest variation of mass - 0.01 to 10 times the mass of the Milky Way

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10
Q

Explain Spiral Galaxies:

A 
Uniform size
Distinct spiral arms and disk
Mixture of population 1 and 2 stars
Mixture of gas and dust
Smaller than Milky Way - some are 4-5 times bigger and 10 times brighter.
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11
Q

How big is a Planck Length?

A

10 to the -35m

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12
Q

How big is a Quark and what us a similar size?

A

10 to the -17m & Gluons which holds quarks together

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13
Q

How big is a nucleus?

A

10 to the -14m

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14
Q

How big is the Earth?

A

10 to the 8m

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15
Q

How big is the solar system?

A

10 to the 13m

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16
Q

How big is our spiral arm?

A

10 to the 20m

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17
Q

How big is the Virgo Cluster

A

10 to the 23m

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18
Q

How big is the visible universe?

A

10 to the 26m

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19
Q

What came before the Big Bang?

A

Nothing. Time and space began with it.

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20
Q

How hot and dense is the Universe?

A

Infinite density and temperature but with a finite past.

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21
Q

What happens as the Universe expands?

A

It cools down.

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22
Q

What happened at 10 to the -35 seconds?

A

Cosmic inflation occurred
The Universe grew exponentially.
Then it consisted of elementary particles.

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23
Q

What was the Annihilation phase of the Big Bang?

A

Anti-matter and matter were being constantly created and destroyed in collisions.

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24
Q

When did Quarks and Gluons form protons and neutrons?

A

10 to the -6 seconds.

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25
Q

What happened after a few minutes into the Big Bang?

A

Temperature at about a billion Kelvin, forming the first nuclei of elements.

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26
Q

When were atoms formed? Complete with electrons?

A

379,000 years after the Big Bang. Radiation then separated from matter and continued travelling through space. This radiation = cosmic microwave background radiation.

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27
Q

What were the 6 stages of the Big Bang?

A
  1. Bang
  2. Inflation
  3. Annihilation
  4. Nuclei
  5. Atoms
  6. Radiation
28
Q

What happens when we view deep space?

A

Seeing into the past.

29
Q

What did Hubble discover?

A

That the galaxies are rapidly moving away from us. The one’s further away are moving faster.

30
Q

Which was the first force to emerge from the Big Bang?

31
Q

What was the state of the Universe at the instant of creation?

A

Infinite temperature, density

Speck of pure energy.

32
Q

What is Einstein’s equation and what does it mean?

A

E = mc^2
Energy can make matter
They can be the same thing

33
Q

When did the first stars form after the Big Bang?

A

200 million years

34
Q

When did the first galaxies form?

A

1 billion years.

35
Q

What is happening to the rate of the expansion of the Universe?

A

Speeding up- Dark Energy overcame gravity

36
Q

What is dark energy doing?

A

Pulling galaxies apart

Stars slowly go out.

37
Q

Evidence for the Big Bang?

A

Hubble-Type expansion- redshift of galaxies
Cosmic Microwave Background Radiation - Measurements of
Abundance of lighter elements like Hydrogen.
Large Scale Distribution - cooling areas = denser - needed heat to expand

38
Q

Explain Schrödinger’s Cat:

A

If you put a cat in a box with a bomb that has a 50% chance of exploding in the next minute, you won’t know if the cat is dead or alive until you open the box. Until you look the cat is both dead and alive though when you look the superposition collapses and the cat is one or the other.

39
Q

What is dark matter?

A

Accounts for most of the mass in the universe
Surrounds galaxies
Does not reflect light
Gravitational effects on the matter we do see.

40
Q

Evidence of dark matter?

A

Rotation of galaxies
The speed of stars on the outer skirts of the galaxy travel at relatively the same speed as the ones close to the main gravity source.
Keeps balance in the galaxy.

41
Q

What is special relativity?

A

All motion is relative. No preferred frame of reference

In every frame of reference, the speed of light is constant.

42
Q

Implications of Special Theory?

A

Time Dilation - Time on a fast moving object appears to slow down when measured by a stationary observer
Length Contraction - The length of the fast moving objects appears to be shorter to the stationary observer.

Fast moving objects fall through space faster, so falls through time slower.

43
Q

Twins Paradox?

A

Twin who stays on Earth ages faster than the twin who takes a high speed journey.

44
Q

What is general relativity?

A

Mass warps spacetime.
Time slows near massive objects.
Best path for objects and light is to curve with gravity - orbits.

45
Q

Evidence of general relativity?

A

Eclipse of 1919- stars shift near sun.

46
Q

What are the three theories for Multiverses?

A
  1. Bubble Universe
  2. Membranes
  3. Many Worlds
47
Q

Explain Bubble Universe?

A

Each bubble has different laws and is cut off from the others. Ours is the only one where the rules allow human life.

48
Q

Explain Membranes Theory?

A

Extra dimensions. Our universe is a 3D universe embedded in a 9D everything. Like pages in a newspaper.

49
Q

Explain Many Worlds Theory?

A

Quantum Mechanics. Collapse of quantum events. Every possible event happens. Each decision makes a spin off universe.

50
Q

How could you travel to the ‘Future’?

A
  1. Travel at the speed of light
  2. Travel near an object of enormous gravity
    Time slows down while the rest of the universe has more time elapsing.
51
Q

How could you travel to the past?

A

Impossible because it violates rules of cause and effect.

52
Q

What is the Grandfather paradox?

A 
You go back in time and kill you grandfather before he meets your grandmother.
But then you would never have been born.
So you couldn't have killed him.
So he would have lived.
And you would have been born. 
So you could kill him. 
And so on. And so on.
53
Q

What are the 5 eras of the past and future?

A
  1. Primordial Era
  2. Stelliferous Era
  3. Degenerate Era
  4. Black Hole Era
  5. Dark Era
54
Q

Explain the Primordial Era?

A

0-1million years
Big Bang
Before first stars

55
Q

Explain the Stellifierous Era?

A

10 to the 6 - 10 to the 14 years
Era of stars
Our Era

56
Q

Explain the Degenerate Era?

A 
10 to the 14 - 10 to the 40 years
Star formation ceases
Dominated by white dwarves and neutron stars
Galaxies disperse
Occasional rogue planet
Star clusters join
57
Q

Explain the Black Hole Era?

A

10 to the 40 - 10 to the 100 years
Protons have decayed
Matter as we know deceases
Black holes dominate
Hawking radiation explodes bigger and bigger black holes
Stellar sized black holes die around 10 to the 67 years
Supermassive sized black holes die around 10 to the 100 years

58
Q

Explain the Dark Era?

A

Universe virtually empty
Photons, Electrons, Positrons and Dark Matter dominate
“Positronium” - “temporary atom” of positron and electron

59
Q

What is dark energy and what is it doing?

A

Dark Energy is the mysterious force that is speeding uo the expansion of the Universe.

60
Q

What is the Higgs Boson?

A

It is an excitation of the Higgs Field.
Involved in the weak nuclear force.
Clump in the Higgs field where it is interacting with itself.

61
Q

What is the Theory of Everything?

A

Explains the standard model.
Matter takes up space - can’t have 2 particles at the same point in space.
Force is exchanged between particles (gauge bosons)
Transfer momentum from one object to another.

62
Q

What is the standard model?

A

6 quarks
6 leptons
4 bosons
Higgs Boson

63
Q

What is the String Theory?

A

Super small strings, smaller than the planck length
Unifies gravity
Extra dimensions
Depending on how they vibrate,determines what type of particle they become.

64
Q

Explain Wave Particle Duality?

A

Light and Matter have both wave and particle nature.
The position and speed of a particle can’t be certainly determined.
Explaining how the main forces work.

65
Q

What theories try to connect quantum physics with classical physics?

A

Spontaneous Collapse
Pilot Wave
Many Worlds

66
Q

Quantum Uncertainty?

A

The more accurately you measure the speed of a particle, the less accurate the position reading is. And vice versa.

HDSO Astronomy (9 decks)

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