100

Question 1

Front

Answer 1

Back

Question 2

What is the Friedmann equation?

Answer 2

H² = (8πG/3)ρ - k/a² + Λ/3

Question 3

What is the critical density?

Answer 3

ρ_c = 3H² / (8πG)

Question 4

What condition defines a flat universe?

Answer 4

Ω = ρ/ρ_c = 1

Question 5

What is the definition of Hubble parameter H?

Answer 5

H = (dot{a})/a — the rate of expansion of the universe

Question 6

What is the scale factor a(t)?

Answer 6

It describes how distances expand over time in the universe

Question 7

What problem does SUSY solve?

Answer 7

Hierarchy problem

Question 8

What does SUSY predict for every SM particle?

Answer 8

A superpartner with spin differing by ½

Question 9

What is the LSP in SUSY?

Answer 9

Lightest Supersymmetric Particle, often the neutralino

Question 10

Why is the LSP a dark matter candidate?

Answer 10

It’s stable, massive, and neutral

Question 11

What is R-parity?

Answer 11

R = (-1)^{3(B - L) + 2s}; conserved in many SUSY models

Question 12

When does Big Bang Nucleosynthesis occur?

Answer 12

From ~1 second to ~3 minutes after the Big Bang

Question 13

What is the key output of BBN?

Answer 13

Primordial abundances of light nuclei like H, He, D, Li

Question 14

What determines the neutron-to-proton ratio?

Answer 14

n/p ≈ exp(-Δm/T)

Question 15

Why is Deuterium abundance a good cosmological probe?

Answer 15

It is very sensitive to baryon density

Question 16

What is the approximate Helium-4 mass fraction from BBN?

Answer 16

~25%

Question 17

What are neutrino oscillations?

Answer 17

Flavor changes of neutrinos due to mass differences

Question 18

What is the oscillation probability formula?

Answer 18

P = sin²(2θ) sin²(1.27 Δm² L / E)

Question 19

What experiment confirmed atmospheric neutrino oscillations?

Answer 19

Super-Kamiokande

Question 20

What solved the solar neutrino problem?

Answer 20

Detection of all neutrino flavors by SNO

Question 21

What is the MSW effect?

Answer 21

Matter-induced enhancement of neutrino oscillation in the Sun

Question 22

What is inflation?

Answer 22

Rapid exponential expansion in the early universe

Question 23

What problem does inflation solve?

Answer 23

Horizon, flatness, and monopole problems

Question 24

What is the inflationary scale factor?

Answer 24

a(t) ∝ exp(Ht)

Question 25

What causes density perturbations during inflation?

Answer 25

Quantum fluctuations stretched to cosmic scales

Question 26

What are slow-roll conditions?

Answer 26

ε, η ≪ 1 ensure sustained inflation

Question 27

What is the CMB?

Answer 27

Relic radiation from recombination (~380,000 years after Big Bang)

Question 28

What is the typical CMB temperature?

Answer 28

~2.725 K

Question 29

What is the typical anisotropy amplitude?

Answer 29

ΔT / T ≈ 10⁻⁵

Question 30

What does the first acoustic peak indicate?

Answer 30

The curvature of the universe

Question 31

What do the peak heights in the power spectrum show?

Answer 31

Relative baryon and dark matter densities

Question 32

What are main pieces of evidence for dark matter?

Answer 32

Rotation curves, lensing, CMB, LSS

Question 33

What is a WIMP?

Answer 33

Weakly Interacting Massive Particle — dark matter candidate

Question 34

Name a dark matter detection experiment.

Answer 34

XENON1T

Question 35

What is indirect detection of dark matter?

Answer 35

Looking for annihilation/decay products (γ, ν, e⁺)

Question 36

What is the role of LHC in dark matter detection?

Answer 36

Search for missing energy signatures

Question 37

What is the equation of state for dark energy?

Answer 37

P = wρ

Question 38

What value of w corresponds to a cosmological constant?

Answer 38

w = -1

Question 39

What evidence supports dark energy?

Answer 39

Type Ia supernovae, CMB, large-scale structure

Question 40

What is quintessence?

Answer 40

Dynamic scalar field alternative to Λ

Question 41

How much of the universe is dark energy?

Answer 41

~70%

Question 42

What is the form of the cosmic ray spectrum?

Answer 42

dN/dE ∝ E^{-γ}

Question 43

What is the 'knee' in the spectrum?

Answer 43

~10¹⁵ eV — galactic limit

Question 44

What is the 'ankle'?

Answer 44

~10¹⁸.⁵ eV — transition to extragalactic sources

Question 45

What is the GZK cutoff?

Answer 45

Suppression above ~5×10¹⁹ eV due to CMB interactions

Question 46

What is Fermi acceleration?

Answer 46

Energy gain by particles crossing magnetic shock fronts

Question 47

Where are solar neutrinos produced?

Answer 47

In nuclear reactions in the Sun’s core

Question 48

What event first detected supernova neutrinos?

Answer 48

SN1987A

Question 49

What is IceCube?

Answer 49

A neutrino observatory at the South Pole detecting Cherenkov light

Question 50

What energy range does IceCube detect?

Answer 50

TeV to PeV

Question 51

What is the Glashow resonance?

Answer 51

ν̄_e + e⁻ → W⁻ at ~6.3 PeV