Untitled Class > Astronomy test #2 > Flashcards

Astronomy test #2 Flashcards

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1
Q

Physical measurements of change

A

-time is a measure of change
-change involves the expenditure of energy
-Times involves irreversibility
-time itself can be seen as a circle/cycle
-it was a judo-christian tradition that imposed a “linear”, irreversible time in western culture.

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2
Q

Pendulum

A

a swinging clock. The period of swings is equal to the period the swings die out at.

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3
Q

Atomic clocks

A

uses photons to measure time.

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4
Q

Pulsars

A

Dead/Neutron star that spins like a lighthouse. Perfect for measuring time devices for eons.

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5
Q

Newtons definition of time

A

Time is necessarily absolute. This means that all events could be regarded as having a distinct and definite place in space and time.

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6
Q

Einsteins concept of time

A

Time is stretchable and varied from place to place.

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7
Q

Special Relativity

A

time stretches when you move with any speed. The biggest effect is when you move at speeds close to a billion km/h

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8
Q

General Relativity

A

Time becomes stretched when you place yourself in a gravitational field. The effect is biggest when the gravitational field is strong.

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9
Q

light cone

A

light rays will always travel along paths at 45 degree angles. These lines form the light cone.

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10
Q

presentism

A

the past and the future does not exist- the universe consists of only the current moment.

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11
Q

The evolving block universe

A

the present is the boundary of spacetime as it expands into the future.

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12
Q

Eternalism: the block universe

A

the past, present and future all coexist in a block universe

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13
Q

Entropy

A

the number of ways a system can be re-arranged without changing it’s basic appearance. Entropy increases with time.

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14
Q

Laws of thermodynamics #1

A

you can’t get something from nothing. Commonly referred to as “conservation of energy”. All of the energy that gets put into the process must be equal to all of the energy that comes out of it.

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15
Q

Laws of thermodynamics #2

A

You can’t break even in “the game” (life). No matter what you do in life, there will always be a “disorder” price to pay. Real world processes either generate more disorder, or they simply don’t happen. The entropy of the complete system always increases.

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16
Q

Laws of thermodynamics #3

A

you can’t opt out of the game. For something to exist, it will always have a little bit of energy, meaning the entropy will never go to zero.

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17
Q

Disorder

A

Disorder is measured by entropy. Messier, less-organized things have higher entropy.

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18
Q

Big Bang

A

Early-microwave background. smooth and dense - low entropy.

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19
Q

Today

A

galaxy distribution. Lumpy and sparse - medium entropy.

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20
Q

future

A

empty space. Dilute and cold - high entropy.

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21
Q

General relativity: time travel

A

In general relativity, you leave the earth and orbit a very dense object for a small amount of time. The closer you orbit the dense object, to further you travel into the future.

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22
Q

Special relativity: time travel

A

In special relativity, all you have to do is leave the earth behind and travel in a super fast spaceship. Your time intervals will dilate, making your clocks very slow compared to those on earth. You will have aged a small fraction of the same of those on earth.

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23
Q

Grandfather paradox

A

You cannot travel to the past and disrupt som event in such a way that you never existed in the first place. For example, if you really did kill your own grandfather, you shouldn’t exist at all.

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24
Q

“No free lunch” paradox

A

within the same universe, time travelers should not be able to bring information and energy to the past that could be used to create new ideas and/or products. For example, Picasso travels to the past to meet his younger self and gives him copies of his art. If Picasso copied them perfectly, he could have affected the future of 20th century art at a very early age.

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25
wormholes
Time travelling using wormholes that either connect our universe with itself at an earlier time, or with some other universe that is a copy of ours at an earlier time.
26
Euclidean geometry
basic, solid geometry, used for two and three dimensional figures, and is the geometry taught in school.
27
spherical/positive curvature
the angles inside triangles add up to be more than 180 degrees.
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flat/zero curvature
the angles of a triangle add up to be 180 degrees exactly.
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Hyperbolic/negative curvature
the inside angles of a triangle add up to be less than 180 degrees.
30
Einsteins general theory of relativity (in the curvature of space)
The geometry of space at any location in the universe is directly related to the strength of the gravitational field at that location.
31
The positive curvature universe/closed universe
a universe that will expand to a certain separation between galaxies, then contract back to zero.
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The zero curvature universe/spatially-flat universe
A universe that will expand forever, slowing sown as it does so
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The negative curvature universe/open universe
A universe that will expand forever.
34
Topology
The branch of mathematics concerned with the ramifications of continuity. Emphasizes the properties of shapes that remain unchanged no matter how much the shapes are bent, twisted, or manipulated otherwise.
35
Mobius strip
mathematical abstract concept. defined as a 2D object. A flat, 2D strip folded into a continuous circle, becoming a 2D object in a 3D form.
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Klein bottle
the "object" version of the mobius strip. A surface that results when two mobius strips are glued together edge-to-edge.
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Dimensionality
there are three different degrees of freedom of movement. You can go: left or right, forward or backward, and up or down
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Bernhard Riemann
generalized euclidean geometry to non-euclidean geometry, which allowed for curved surfaces and any number of higher dimensions.
39
Tesseract
A four-dimensional hypercube, created by Charles Hinton. The generalization of the three dimensional cube. All of its edges must be the same length.
40
strong (nuclear) force
holds quarks in hadrons and the nucleus together. Also known as the colour force, and only acts on quarks (found in atomic nuclei) since only they have colour charge.
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electromagnetic force
holds atoms and molecules together. Most things we experience daily is a result of this force. bigger objects and many particles have no overall charge.
42
Weak nuclear force
Responsible for radioactive decay involving electrons, called beta decay, and is crucial for how the sun gives off energy. Acts on all point particles (baryons, mesons and leptons).
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Electroweak
A theory combining electromagnetic and weak nuclear force.
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Force
a change in momentum/velocity of an object.
45
momentum
amount of motion. Mass x velocity.
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velocity
change of position in interval of time.
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force carrier particle
mediate the fundamental forces between other particles. responsible for all electromagnetic forces. For example, throwing a ball to each other on an ice rink; the force that causes you to be pushed back upon impact of the ball
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Newtons law (electrical force)
The force between two objets is proportional to the product of their masses divided by the square of the distance between them.
49
Coulombs electrical law
the force between two objects is proportional to the product of their charges divided by the square of the distance between them.
50
gravitational force
binds the planets in our solar system to the sun, and the sun to the Milky Way.
51
Graviton
the force carrier of the gravitational force. Predicted to have no mass.
52
Photon
the force carrier of the electromagnetic force, represented by the greek letter "gamma" (y).
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coloured particles
Three coloured particles called Baryon, and two coloured particles called a Meson.
54
Gluon
force carrier of the strong/nuclear/colour force. represented by the letter g.
55
Electron
Responsible for the flow of electricity, and all chemical reactions. Has a negative electric charge.
56
Neutrino
A lepton particle that interacts only with the weak force.
57
Intermediate vector boson
the force carrier of the weak force. very massive. comes in three types: 1) positive electrically-charged (W+), negative electrically-charged (Z⁰)
58
Quarks
The building blocks of all visible matter. The smallest form of particle.
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Fundamental particles
Quarks and Leptons
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Quark generations
Gen 1: up quark and down quark Gen 2: charm quark and strange quark Gen 3: top quark and bottom quark
61
Proton
two up quarks and one down quark. adding up the charge of the quarks gives us: (+2/3) + (+2/3) + (-1/3) = +1
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Neutron
one up quark and two down quarks. (+2/3) + (-1/3) + (-1/3) = 0
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Lepton generations
Gen 1: electron and electron neutrino Gen 2: muon and muon neutrino Gen 3: tau and tau neutrino
64
Sudbury Neutrino observatory (SNO)
heavy-water Cherenkov detector that detects neutrinos produced by fusion reactions in the sun.
65
Gamma rays
The photons (high frequency electromagnetic radiation) that comes from the burst of energy produced from a particle and antiparticle colliding.
66
Pair production
used to construct models of how the universe began. photons can generate a particle-antiparticle pair.
67
Cosmic rays (particles)
99% of all cosmic ray particles are the nuclei of atoms. The majority are protons and helium nuclei. Elements heavier than hydrogen and helium, but lighter than iron, makeup the remaining cosmic rays.
68
Antimatter propulsion
using antimatter to propel spacecraft to very high speeds, by expelling photons from the rear of the ship.
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Problems with Antimatter propulsion
Problem #1: At the moment, obtaining large quantities of anti atoms or antimolecuhles is economically prohibitive. Problem #2: storing antimatter fuel is very difficult. Charged particles can be cut off from the rest of their surroundings by using magnetic fields to redirect them, but it takes a lot of energy to maintain them.
70
Hadrons
A composite subatomic particle. Any particle made of only quarks are hadrons. Every hadron must fall into one of the two fundamental classes of particles: Bosons and Fermions.
71
Mesons
Less fundamental particle than leptons. made from 2 quarks, one up and one down. All mesons are very unstable particles.
72
Baryons
Less fundamental particle than leptons. made from 3 quarks, each being different colour charges. Protons (2 up quarks, 1 down) and Neutrons (1 up, 2 down) are categorized as Baryons.
73
Quantum Chromodynamics
the study of the strong interaction between quarks and gluons.
74
Higgs boson/particle
a special particle that takes on the role of a force carrier. Also referred to as a scalar particle, because of its zero spin value.
75
Higgs field
a background field that spreads itself pervasively throughout the universe. The field is what gives regular particles "mass".
76
Nucleon
The broad classification name for either a neutron or proton when they are in the nucleus.
77
Leftover gluon
when there's leftover gluon after the baryons/quarks are bound, some of that energy leaks out and can effect nearby quarks. This can bind a small number of protons and neutrons together into a composite nucleus.
78
isotope
Type of atom, is the same as any given element in the periodic table, but will have more neutrons.
79
upper limit
proton repulsion can only get so big. Nuclei with lots of protons are unstable, creating a limit to how big a nucleus can grow.
80
Fusion
nucleons are forced closer and closer, until the gluons can act to bind quarks in different nucleons together.
81
Fission
Nuclei are broken up, the strength of gluons is so intense that the fission process doesn't occur until a large number of protons and neutrons have fused together.
82
Binding energy
The residual gluon energy that binds neutrons in nuclei.
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ionizing radiation
when nuclei emit pieces of themselves (as matter/energy), emissions are the sign of radioactivity.
84
Types of radioactivity
1. alpha-particle emission: helium nuclei chunks (2 neutrons and 2 protons) get thrown out. 2. beta-particle emissions: electrons and positrons are made and thrown out. 3. Gamma-ray emissions: Powerful high-frequency photons are thrown out
85
iron
has 56 nucleons; 28 protons and 28 neutron, which is the maximum value of a nuclei that can undergo fusion. Iron doesn't fuse at stellar temperatures.
86
binding energy curve
nuclei with smaller masses than iron undergo fusion. They can join together to make a fat nuclei. Nuclei with bigger masses than iron are likely to under fission.
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Atom
A neutral structure composed of electrons moving around positively charged nuclei in stable orbits (orbitals)
88
Exclusion principle
an electron in an atom is never allowed to be in exactly the same quantum state as another electron.
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fermion
particles with spin angular momentum equal to half values. Always interacts with each other using force carrier particles (bosons).
90
ionic bonding
if an atom "wants" an electron, so that it can complete its outer shell, it will "steal" another atoms electron. They will end up with an imbalanced charge (one positive and one negative). This charge will form a strong ionic bond.
91
Hydrogen bonding
a weak bond formed when a hydrogen atom is shared between two molecules.
92
Atom Organization
depends on: 1) the behaviour of the outer electron 2) The unique behaviour of the hydrogen atom 3) the special properties of a pair of atoms forming highly directed bonds in a tetrahedral configuration.
93
Tetrahedral bonding
The geometry of a molecule with a central atom bonded to four other atoms, resulting in a bond angle of 109.5. This arises from the repulsion of electron pairs.
94
Diamond arrangement
Diamond is a combination of carbon atoms in a tetrahedron shape. Very stable and strong. Crystallized carbon atoms
95
Graphite arrangement
The carbon atoms are arranged in flat, honeycomb-like (hexagonal) lattices, with each carbon bonded to three other distinct carbon atoms. Graphite is quite soft. Non-crystallized carbon atoms.
96
Silicon dioxide Silica
major constituent of rocks, sand, cement, glass and ceramics.
97
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