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Things I Should Know > The Universe > Flashcards

The Universe Flashcards

1
Q

The Universe

How old is the universe?

(I.e. how long ago was the Big Bang)?

A

13.8 billion years

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2
Q

The Universe

What is the diameter of the visible universe (as of 2020)?

A

93 billion light-years

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3
Q

The Universe

How long after the Big Bang (13.8 billion years ago) did the first stars begin to form?

A

400 million years

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4
Q

The Universe

Just after the Big Bang, the universe was an expanding ‘soup’ of what?

A

Subatomic particles

(e.g. quarks and leptons)

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5
Q

The Universe

Stars form as cooling condensations of what (under the influence of dark matter)?

A

Hydrogen, helium, and lithium

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6
Q

The Universe

If stars are condensations of hydrogen, helium, and lithium, from where do we get the heavier elements?

A

Star cores, collapsing stars, supernovae

(compressed/formed via pressure and heat; then, seeded out to the universe when the stars die)

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7
Q

The Universe

What is the theory of the ‘heat death of the universe?’

A

The end of the universe: continual expansion for trillions of years as the expanding elements’ temperature approaches absolute zero

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8
Q

The Universe

The initial ‘state’ of the universe lasted a tiny fraction of a second at which point all matter was condensed into a tiny point. This moment is called what?

A

The Planck Epoch

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9
Q

The Universe

The initial “glow” of the Big Bang can be seen throughout space today observed as what?

A

Cosmic microwave background radiation

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10
Q

The Universe

True/False.

The expansion of the universe is decelerating.

A

False.

The expansion of the universe is accelerating.

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11
Q

The Universe

What is causing the acceleration of the universe expansion?

A

Dark energy

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12
Q

The Universe

Is there more matter or antimatter in the universe (or are they equal?)?

A

Matter

(If they were equal, they would just cancel one another out into photons.)

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13
Q

The Universe

From where does the cosmic microwave background radiation we observe in the universe come?

A

The initial “glow” of the Big Bang

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14
Q

The Universe

Name three fundamental physical constants which are highly ‘fine-tuned’ to our universe being able to form matter.

A

The speed of light;

the Planck constant;

the elementary charge

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15
Q

The Universe

Protons and neutrons are made up of what smaller particles?

A

Quarks

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16
Q

The Universe

What is the closest spiral galaxy to ours?

A

The Andromeda galaxy

(which is currently hurtling towards us)

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17
Q

The Universe

What is the closest star/planetary system to ours?

A

Alpha-Centauri

18
Q

The Universe

What is at the center of the Milky Way galaxy?

A

A supermassive black hole

(Sagittarius A)

19
Q

The Universe

In order from closest to furthest from the sun, name the four terrestrial planets of our solar system.

A

Mercury; Venus; Earth; Mars

20
Q

The Universe

In order from closest to furthest from the sun, name the two gas giants of our solar system.

A

Jupiter; Saturn

21
Q

The Universe

In order from closest to furthest from the sun, name the two ice giants of our solar system.

A

Uranus; Neptune

22
Q

The Universe

True/False.

The planetary paths of our solar system all lie in a nearly flat disc called the ecliptic.

A

True.

23
Q

The Universe

Why did our solar system (and many like it) form with its planets in a fairly flat plane?

A

Young stars often form with protoplanetery disks (circumstellar disks) of gas and dust

(these are a form of _accretion disc_)

24
Q

The Universe

The asteroid belt within our solar system is found where?

A

Between Mars and Jupiter

25
Q

The Universe

What is the Kuiper belt?

A

A massive, massive ring of asteroids surrounding our solar system

(It is just outide Neptune’s orbit; it is 20x wider than the asteroid belt and 100x mrore massive.)

26
Q

The Universe

What is the oort cloud?

A

A massive, massive cloud of icy structures which surround our solar system and represent the limits of the sun’s gravitational influence

27
Q

The Universe

The ________ ________s (in the context of the Fermi Paradox) are a series of potential barriers that may explain why we have not identified life in the universe.

A

The great filters (in the context of the Fermi Paradox) are a series of potential barriers that may explain why we have not identified life in the universe.

(I.e., at least one of the steps listed in the attached image must be incredibly unlikely to actually occur.)

28
Q

The Universe

What kind of star is our sun?

A

A white dwarf

29
Q

The Universe

How long from now will our star turn into a red giant, rendering the earth uninhabitable?

A

5 billion years

30
Q

The Universe

What does it mean if something is redshifted relative to us?

A

We are moving away from one another in space

31
Q

The Universe

What does it mean if something is blueshifted relative to us?

A

We are moving toward one another in space

32
Q

The Universe

True/False.

In a section of the vacuum of space, there is no ‘true’ vacuum as some level of energy is almost always present (this leads to the rise of virtual particles, even for a short time).

A

True.

  • (Note 1: Space is a vacuum, not a* void!)
  • (Note 2: Not to mention the effects of dark matter/energy.)*
33
Q

The Universe

The _____________ is a group of principles attempting to determine how statistically probable our observations of the universe are, given that we could only exist in a particular type of universe to start with.

(I.e. is our universe ‘fine-tuned’ for telological reasons, or do we as carbon-based creatures see it as ‘fine-tuned’ simply because we exist and this is the only way we could exist?)

A

The anthropic principle is a group of principles attempting to determine how statistically probable our observations of the universe are, given that we could only exist in a particular type of universe to start with​.

(I.e. is our universe ‘fine-tuned’ for telological reasons, or do we as carbon-based creatures see it as ‘fine-tuned’ simply because we exist and this is the only way we could exist?)

34
Q

The Universe

What is the name of the equation put together to give a rough range (based off a number of conjectural estimates) of how many active, communicative civilizations are extant in the Milky Way galaxy?

A

The Drake Equation

35
Q

The Universe

Name some of the factors represented in the Drake equation (which attempts to identify N, the number of active, communicative civilizations within the Milky Way galaxy)?

A

N =

the average rate of star formation *

the fraction of those stars that have planets *

the average number of planets that can potentially support life (per star that has planets) *

the fraction of those that develop life at some point *

the fraction of those that develop intelligent civilizations *

the fraction of those that develop a technology that releases detectable signs of their existence into space *

the length of time for which such civilizations release detectable signals into space

36
Q

The Universe

What is the Fermi paradox?

A

The contradiction between the lack of evidence and the high probability estimates for existence of extraterrestrial civilizations

37
Q

The Universe

What is Kepler’s first law of planetary motion?

A

The orbit of any planet is an ellipse with the sun at one of the ellipse foci

38
Q

The Universe

True/False.

Planetary motion is near circular in regards to the sun, with the sun at the center of the circular route.

A

False.

Planetary motion is elliptical in regards to the sun, with the sun at one of the two foci of the ellipse.

39
Q

The Universe

Kepler’s second law of planetary motion is that basically that a line between the sun and the planet sweeps an equal area of space in equal amounts of time.

What does this mean in practical effect?

A

The planets must speed up when they are near the sun

40
Q

The Universe

What is Kepler’s third law of planetary motion?

A

A planet’s orbital time squared is equal to its average distance from the sun cubed

POrbitalTime2 = ADistanceToSun3

Things I Should Know (52 decks)

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