Cosmology Forum

Post thread
Join in expert discussion on topics revolving around cosmology. Cosmology is the origin, evolution, structure and eventual fate of the universe.
High School How to explain "the right hand rule" to an alien universe
  • · Replies 15 ·
Replies
15
Views
5K
Undergrad Exponential expansion and the Cosmological Constant
  • · Replies 7 ·
Replies
7
Views
2K
Undergrad Imaging galaxies receding at a velocity that exceeds c?
  • · Replies 12 ·
Replies
12
Views
4K
High School What is the most common/likely process of the Universe?
  • · Replies 7 ·
Replies
7
Views
2K
Graduate Covariance matrix size: 3x3 or 4x4?
  • · Replies 5 ·
Replies
5
Views
2K
Graduate CMB as thermal radiation of cosmic dust?
  • · Replies 8 ·
Replies
8
Views
3K
Undergrad How does Hawking radiation contribute to the formation of new stars?
  • · Replies 28 ·
Replies
28
Views
5K
Graduate Classical scalar field as Dark Matter
  • · Replies 14 ·
Replies
14
Views
3K
Undergrad Fine tuning and the multiverse
  • · Replies 6 ·
Replies
6
Views
3K
Graduate Cosmological fluctuations (Weinberg's cosmology, p. 284)
  • · Replies 10 ·
Replies
10
Views
3K
High School What is the 'proof' of the no-hair theorem of black holes?
  • · Replies 5 ·
Replies
5
Views
3K
High School CMBR: Is It Constant or Changing Over Time?
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Cross-correlations: what size to select for the matrix?
  • · Replies 4 ·
Replies
4
Views
2K
Graduate Dark matter and the fabric of space time,
  • · Replies 2 ·
Replies
2
Views
2K
High School Which Hawking paper? (no singularity at the beginning of the universe)
  • · Replies 2 ·
Replies
2
Views
3K
Is "Broken Symmetry" truly foundational?
  • · Replies 4 ·
Replies
4
Views
2K
Graduate Decoupling of SVT Metric Perturbations
  • · Replies 2 ·
Replies
2
Views
2K
High School Help with when expansion acceleration began
  • · Replies 23 ·
Replies
23
Views
3K
High School Can a single photon make up a universe?
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Why ##\omega=0## for a matter dominated universe?
  • · Replies 4 ·
Replies
4
Views
2K
Undergrad Is a "collision" of galaxies noticeable on a planetary scale
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Expansion of positively and negatively curved universe
  • · Replies 2 ·
Replies
2
Views
1K
Undergrad Variable Dark Energy: Would P Remain Constant?
  • · Replies 17 ·
Replies
17
Views
2K
Undergrad Is Something Missing in the Expansion of Our Flat Universe?
  • · Replies 17 ·
Replies
17
Views
2K
High School What Happens at the Event Horizon of a Black Hole?
  • · Replies 5 ·
Replies
5
Views
2K
High School Andromeda Collision VS Expansion
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad New Problems I have with Dark Matter
  • · Replies 13 ·
Replies
13
Views
3K
Undergrad What Is the Singularity and Its Role in the Big Bang?
  • · Replies 26 ·
Replies
26
Views
4K
Undergrad Difference between dark energy and dark matter
  • · Replies 6 ·
Replies
6
Views
2K
High School How exactly inflation solves the Horizon Problem
  • · Replies 13 ·
Replies
13
Views
4K
Undergrad Relative Amount of Hydrogen in the Universe
  • · Replies 8 ·
Replies
8
Views
3K
Undergrad Inflation resolves the horizon problem
  • · Replies 7 ·
Replies
7
Views
2K
High School Naked Singularity, Black hole mass limit
  • · Replies 12 ·
Replies
12
Views
2K
Undergrad Supermassive singularity the cause of the Big Bang?
  • · Replies 32 ·
2
Replies
32
Views
4K
Undergrad The Universe as an isolated system
  • · Replies 27 ·
Replies
27
Views
4K
Undergrad Dark energy and the rotation curve of spiral galaxies
  • · Replies 1 ·
Replies
1
Views
1K
High School Active galaxies point to new physics of cosmic expansion
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Inflation and the size of the Universe
  • · Replies 9 ·
Replies
9
Views
3K
Undergrad What is the Hubble Parameter over time and how can I calculate it?
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Luminosity Distance: Finding the Connection
  • · Replies 15 ·
Replies
15
Views
3K
High School Algebraic Topology in the tv show The Big Bang Theory
  • · Replies 11 ·
Replies
11
Views
21K
Undergrad Relationship between Energy density and Curvature
  • · Replies 27 ·
Replies
27
Views
5K
Undergrad Sachs-Wolfe effect and Superclusters/Supervoids
  • · Replies 7 ·
Replies
7
Views
2K
Undergrad Relativistic Reference Frames and the Big Bang?
  • · Replies 6 ·
Replies
6
Views
2K
Undergrad What Are the Boundaries of a Flat and Saddle-Shaped Universe?
  • · Replies 24 ·
Replies
24
Views
4K
Undergrad What are the latest thoughts about the timescape cosmology
  • · Replies 12 ·
Replies
12
Views
5K
Undergrad Theory behind how expansion moves mass but doesn't interfere with inertia?
  • · Replies 21 ·
Replies
21
Views
3K
High School Comoving distance in cosmology
  • · Replies 1 ·
Replies
1
Views
2K
High School Do Black holes reach a critical mass?
  • · Replies 3 ·
Replies
3
Views
3K
Graduate Hot dark matter constrained by the CMB
  • · Replies 7 ·
Replies
7
Views
2K
High School Missing Dark Matter of NGC1052-DF2
  • · Replies 1 ·
Replies
1
Views
1K
Undergrad Why does an Empty Universe have to obey Negative Curvature?
  • · Replies 10 ·
Replies
10
Views
3K
Undergrad Event Horizon and Particle Horizon
  • · Replies 12 ·
Replies
12
Views
4K
High School Ratio between the sizes of the Observed and the Entire Universe
  • · Replies 7 ·
Replies
7
Views
3K
Undergrad Confusion about the math of the Comoving Coordinates
  • · Replies 8 ·
Replies
8
Views
3K
Undergrad Metric of the Universe and dependence on Cosmological P
  • · Replies 7 ·
Replies
7
Views
2K
Graduate Unification of dark energy and dark matter
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Could Our Universe Be a Mirror Image of an Antimatter Universe?
  • · Replies 6 ·
Replies
6
Views
2K
High School The k term in the Friedmann equation
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad The Expanding Universe and a stationary frame of reference
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Footnote on page 151 of Weinberg's Cosmology book
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Is there any evidence of a universe expansion jerk
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Calculating dark energy and matter density
  • · Replies 18 ·
Replies
18
Views
3K
Undergrad Curvature of space in large regions: zero or not?
  • · Replies 9 ·
Replies
9
Views
2K
High School Galaxy Collisions & Expansion: What's Going On?
  • · Replies 3 ·
Replies
3
Views
2K
High School The Impact of Expansion on the Observable Universe
  • · Replies 10 ·
Replies
10
Views
3K
High School Why are ds and dω taken as zero in calculating proper distance in cosmology?
  • · Replies 24 ·
Replies
24
Views
4K
Undergrad How does gravity vary in deep mines and interstellar gas?
  • · Replies 6 ·
Replies
6
Views
2K
High School Space Time fabric graphic is misleading
  • · Replies 4 ·
Replies
4
Views
2K
Undergrad Expansion of 3-D positively curved space
  • · Replies 4 ·
Replies
4
Views
1K
Undergrad What is the energy density of spacetime?
  • · Replies 20 ·
Replies
20
Views
4K
High School Question regarding if curvature is not constant
  • · Replies 6 ·
Replies
6
Views
2K
Undergrad Legendre polynomials in boosted temperature approximation
  • · Replies 8 ·
Replies
8
Views
2K
High School Positive curvature of a 2D surface
  • · Replies 24 ·
Replies
24
Views
4K
High School Dark matter research paper question
  • · Replies 8 ·
Replies
8
Views
2K
Undergrad Are there issues with Conformal Gravity as a DM solution?
  • · Replies 5 ·
Replies
5
Views
3K
Undergrad Total number density of galaxies and problematic expression
  • · Replies 15 ·
Replies
15
Views
3K
Undergrad Infer the distance of a closest neighbor galaxy from correlation
  • · Replies 9 ·
Replies
9
Views
2K
High School Was the initial condition extremely cold?
  • · Replies 10 ·
Replies
10
Views
2K
Undergrad Matter density in Weinberg's Cosmology book
  • · Replies 5 ·
Replies
5
Views
2K
Undergrad Is the inflationary universe a scientific theory?
  • · Replies 3 ·
Replies
3
Views
2K
High School Dark matter is "normal" matter in black holes?
  • · Replies 7 ·
Replies
7
Views
2K
Undergrad Is the increment of the expanding universe part of cosmology
  • · Replies 6 ·
Replies
6
Views
2K
Undergrad What happens to a star's heat when it gets torn apart by a black hole?
  • · Replies 11 ·
Replies
11
Views
2K
Graduate Model of the Universe/Multiverse
  • · Replies 5 ·
Replies
5
Views
2K
High School Discuss Dark Matter & Light: Photons Affecting Space-Time?
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Definition of 'dynamical equilibrium'?
  • · Replies 7 ·
Replies
7
Views
2K
Undergrad What was there before everything came to existence?
  • · Replies 39 ·
2
Replies
39
Views
5K
Undergrad How many galaxies do we have red shift data for?
  • · Replies 15 ·
Replies
15
Views
3K
Undergrad Interpreting the Behavior of Galaxies in an Expanding Universe
  • · Replies 8 ·
Replies
8
Views
2K
High School HSC dark matter survey...where is it?
  • · Replies 1 ·
Replies
1
Views
1K
High School Is the energy of empty space concentrated differently in curved spacetime?
  • · Replies 12 ·
Replies
12
Views
2K
High School The Red Light Shift and Space Debris
  • · Replies 5 ·
Replies
5
Views
2K
Undergrad What is the acceleration of the universe?
  • · Replies 11 ·
Replies
11
Views
3K
High School How Does Time Dilation Vary Across the Galaxy?
  • · Replies 4 ·
Replies
4
Views
2K
High School Expansion or Attraction: What's Driving Our Universe?
  • · Replies 24 ·
Replies
24
Views
3K
Undergrad How do we know age of the universe?
  • · Replies 14 ·
Replies
14
Views
3K
Graduate How are parameters in inflation models tuned to align with CMB constraints?
  • · Replies 1 ·
Replies
1
Views
2K
Graduate How much does peculiar velocity affect distance measurement?
  • · Replies 2 ·
Replies
2
Views
1K
High School What is the reasoning behind MOND's modification of gravity?
  • · Replies 6 ·
Replies
6
Views
2K