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Astronomy > Lecture 13 > Flashcards

Lecture 13 Flashcards

1
Q

Scientists involved in the Big Bang

A 
Georges Lemaitre
Edwin Hubble
George Gamow
Fred Hoyle
Penzias and Wilson
Robert Dicke
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2
Q

George Lemaitre

A
  • Proposed the ‘expanding universe idea’ and reconciled it with Einstein’s equations of relativity
  • suggested the universe started as an infinitely hot dense object called ‘primeval atom’ (singularity)
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3
Q

Who came up with the name ‘cosmic egg’

A

Lemaitres

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4
Q

Edwin Hubble

A

his observations of cepheid variables (stars that vary in luminosity) in the Andromeda galaxy allowed him to determine the distance to the galaxies

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5
Q

Hubble’s Law findings

A

used the redshift of galaxies (determined by vesto slipher 1912) to recognize the further away a galaxy is the faster they are moving away from each other

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6
Q

Hubble’s Law equation

A

d=v/Ho

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7
Q

George Gamow

A
  • created gamow’s theory

- radiation from the initial explosion may still be detected in the form of microwaves

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8
Q

Gamow’s Theory

A

if everything is moving away from everything else (the further apart objects are, the faster they are moving) then at some point everything must have been at one point together in space (singularity)

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9
Q

Fred Hoyle

A
  • came up with the name big bang

- believed in a ‘steady state’

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10
Q

How old did hubble believe the age of the universe to be?

A

2 billion years old

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11
Q

How old is the universe?

A

13.82 billion years old

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12
Q

Why did hubble get the age of the universe wrong?

A

his distance measurements were not very accurate

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13
Q

What did Einstein’s belief in a steady state universe lead to?

A

his cosmological constant

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14
Q

What did Penzias and Wilson find?

A

cosmic background radiation from the big bang

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15
Q

What were Penzias and wilson originally looking for?

A

radio wave signals from the milky way

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16
Q

Who did P&W call to get rid of the ‘background noise’?

A

Robert Dicke

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17
Q

What was Robert Dicke looking for?

A

cosmic background radiation from the big bang

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18
Q

How far apart were P&W and Dicke?

A

less than 30 miles, Bell labs antenna and Princeton

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19
Q

Who won the 1978 nobel prize in physics?

A

Penzias and Wilson, for the discovery of Cosmic microwave background radiation

20
Q

What are evidence of the big bang?

A
  1. redshift of galaxies
  2. cosmic microwave background radiation
  3. composition of very distant objects
21
Q

What is the red-shift of galaxies?

A

-color of light emitted by the galaxies shows that they are all moving away from us (furthest away are moving extremely quickly)

22
Q

Cosmic microwave background radiation is defined as

A

light left over from the initial flood of light emitted by the big bang has expanded (cooled) to microwave wavelengths

23
Q

CMBR comes from

A

all directions with almost equal intensity

24
Q

Composition of very distant objects

A

when we observe distant objects we are seeing them as they were millions or billions of years ago

25
Q

If an object is 1 million light years away we see it as…

A

as it was 1 million years ago

26
Q

What distant objects do we see?

A

clouds of gas (mostly hydrogen and helium)

27
Q

What is a cyclical universe?

A

‘big bounce’, the big bang is just one of a series of big crunches

28
Q

The universe will eventually stop…

A

expanding, then contract to a singularity and expand again

29
Q

What idea did the big bounce come from?

A

the idea that the big bang created time and space

30
Q

What is ‘time’s arrow’

A

if there are universes popping up all of the time (multiverse) some with time arrows in one direction and some with time arrows in the opposite direction will balance out and there is no beginning or end

31
Q

composition of the universe

A
  • 68% dark energy
  • 27% dark matter
  • 5% normal matter
32
Q

What makes scientists think there is matter and energy that we cannot detect?

A

galaxy rotation curves

33
Q

Predictions of galaxy rotation curves

A

stars in a spiral galaxy towards the central bulge should be moving fastest & stars in the spiral arms and halo should be moving slowest

34
Q

What are our prediction of galaxy rotation curves based on?

A

Kepler’s laws describing planetary motion

35
Q

Observations of galaxy rotation curves

A

velocity is the same across the whole galaxy, does NOT slow down the further out you go

36
Q

Explanation of our galaxy rotation curves

A

there must be a heavy (massive) material around the galaxies that keeps fast moving outer stars from flying out of the galaxy (dark matter)

37
Q

Dark matter makes up what percent of everything?

A

27

38
Q

Possible candidates of dark matter

A
  1. massive compact halo objects

2. weakly interacting massive particles

39
Q

Massive compact halo objects

A

form of matter like regular matter that eludes detection

40
Q

regular matter is called

A

baryonic matter

41
Q

weakly interacting massive particles

A

new kind of particle, most likely candidate of dark matter

42
Q

In the 1990s two groups of scientists looked at the most distant type 1 supernovae and found that…

A

these very distant (older) objects are moving away from us, but more slowly than closer (younger) objects

43
Q

Conclusion of the 1990’s distant object findings?

A

the expansion of the universe is speeding up

44
Q

What is causing the universe to expand at an increasing rate?

A

dark energy, astrophysicists dont know what it is

45
Q

What DO we know about dark energy?

A

it is not matter or radiation, it has a repulsive force

46
Q

Who won the 2011 noble prize for physics

A

adam reiss, brian schmidt, and saul perlmuter

47
Q

What did Riess, Schmidt, and perlmuter win the noble prize for?

A

discovering the nature of the expansion of the universe

Astronomy (5 decks)

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