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Cosmology Forum

Join in expert discussion on topics revolving around cosmology. Cosmology is the origin, evolution, structure and eventual fate of the universe.

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I Slow-roll Inflation and Horizon Problem

Jun 18, 2021 · Replies 1 · Jun 18, 2021

Replies: 1

Views: 2K

I Dimensions of Cosmic Scale Factor ##a(t)##

Jun 12, 2021 · Replies 10 · Jun 14, 2021

Replies: 10

Views: 2K

A Relation between Matter Power spectrum and Angular power spectrum

Jun 9, 2021 · Replies 2 · Jun 13, 2021

Replies: 2

Views: 2K

A Expression of the mean and variance of spectroscopic Shot Noise

Jun 6, 2021 · Replies 6 · Jun 7, 2021

Replies: 6

Views: 3K

B What happens to time as space is expanding?

Mar 18, 2021 · Replies 68 · Jun 7, 2021

3

Replies: 68

Views: 9K

I Temperature of the Universe based on the ΛCDM Model

May 23, 2021 · Replies 4 · Jun 5, 2021

Replies: 4

Views: 2K

I Can a Homogeneous Universe Avoid a Big Crunch?

May 29, 2021 · Replies 28 · Jun 5, 2021

Replies: 28

Views: 3K

I Implications if New Dark Matter Maps are Correct?

May 27, 2021 · Replies 9 · Jun 3, 2021

Replies: 9

Views: 2K

B Cosmological constant for the Universe's expansion

May 31, 2021 · Replies 5 · Jun 2, 2021

Replies: 5

Views: 2K

A New Dark Energy Map Challenges Einstein's Theory

May 31, 2021 · Replies 2 · May 31, 2021

Replies: 2

Views: 1K

A Cosmological gravitational waves

May 28, 2021 · Replies 9 · May 28, 2021

Replies: 9

Views: 1K

I New H0LiCOW result: Hubble constant is 73.3 +1.7-1.8 km/(s*Mpc)

Jul 12, 2019 · Replies 29 · May 18, 2021

Replies: 29

Views: 7K

A Fourier transform and Cosmic variance - a few precisions

May 15, 2021 · Replies 4 · May 18, 2021

Replies: 4

Views: 2K

B Feasibility of multiple "big bangs"

May 17, 2021 · Replies 5 · May 17, 2021

Replies: 5

Views: 1K

I Dark energy is intrinsic to the space itself

May 16, 2021 · Replies 5 · May 16, 2021

Replies: 5

Views: 2K

Polling for estimates of probability our universe is infinite

May 16, 2021 · Replies 1 · May 16, 2021

Replies: 1

Views: 2K

I Black Hole Diameter: Is It Finite or Infinite?

May 10, 2021 · Replies 36 · May 16, 2021

2

Replies: 36

Views: 6K

B The Fate of the Universe -- Expansion or Collapse?

May 14, 2021 · Replies 5 · May 14, 2021

Replies: 5

Views: 1K

I What Is the Difference Between Spacetime Curvature and Spatial Curvature?

May 12, 2021 · Replies 18 · May 14, 2021

Replies: 18

Views: 2K

I Proton decay at the end of the Universe

May 6, 2021 · Replies 13 · May 13, 2021

Replies: 13

Views: 2K

I The Hubble constant − constant in what way?

May 5, 2021 · Replies 18 · May 12, 2021

Replies: 18

Views: 2K

I How long would it take the Universe to generate an Earth-like chemistry?

May 10, 2021 · Replies 8 · May 10, 2021

Replies: 8

Views: 2K

I Spatial flatness and cosmological constant

Apr 19, 2021 · Replies 5 · May 5, 2021

Replies: 5

Views: 2K

A What Do Planck 2015 Results Reveal About Power Law Potential Models?

May 4, 2021 · Replies 1 · May 4, 2021

Replies: 1

Views: 1K

I Changing curvature as a universe evolves

Apr 27, 2021 · Replies 36 · May 1, 2021

2

Replies: 36

Views: 4K

I Some questions about baryogenesis

Apr 26, 2021 · Replies 1 · Apr 26, 2021

Replies: 1

Views: 1K

A Angular power spectrum dependence in redshift z and k

Apr 14, 2021 · Replies 5 · Apr 19, 2021

Replies: 5

Views: 2K

I Is the Isotropic Universe Truly Centerless?

Apr 11, 2021 · Replies 23 · Apr 13, 2021

Replies: 23

Views: 2K

Do relativistic effects make the age of the universe moot?

Apr 11, 2021 · Replies 14 · Apr 11, 2021

Replies: 14

Views: 2K

B Question about "our observed universe"

Apr 9, 2021 · Replies 15 · Apr 9, 2021

Replies: 15

Views: 2K

A Looking for sources of information on Black Holes

Apr 8, 2021 · Replies 7 · Apr 8, 2021

Replies: 7

Views: 1K

I How Does a CMB Photon Travel Through Expanding Universe?

Mar 25, 2021 · Replies 39 · Apr 8, 2021

2

Replies: 39

Views: 5K

B 2D Model of the Universe as an expanding ball

Apr 6, 2021 · Replies 4 · Apr 6, 2021

Replies: 4

Views: 2K

A Quintessence field equation of state

Apr 5, 2021 · Replies 3 · Apr 5, 2021

Replies: 3

Views: 2K

B Gravitational fields affecting each other?

Apr 3, 2021 · Replies 21 · Apr 4, 2021

Replies: 21

Views: 2K

I New Paper Claims Primordial Black Holes Don't Explain Dark Matter

Mar 10, 2021 · Replies 20 · Apr 1, 2021

Replies: 20

Views: 4K

I Penrose's Latest Paper on CCC: Evidence or Wishful Thinking?

Mar 24, 2021 · Replies 6 · Mar 28, 2021

Replies: 6

Views: 7K

A Distances between observers using the Lightone7 calculator

Mar 14, 2021 · Replies 17 · Mar 27, 2021

Replies: 17

Views: 2K

A Discrepancy in Jorrie’s LightCone7-2017-02-08 Cosmo-Calculator

Mar 8, 2021 · Replies 15 · Mar 23, 2021

Replies: 15

Views: 2K

B Request for an up to date list of cosmological theories

Mar 22, 2021 · Replies 11 · Mar 22, 2021

Replies: 11

Views: 1K

B A question about which Cosmology theories are mainstream and how?

Mar 21, 2021 · Replies 5 · Mar 21, 2021

Replies: 5

Views: 2K

B Early Universe Radiation: Gamma to Microwave?

Mar 16, 2021 · Replies 42 · Mar 19, 2021

2

Replies: 42

Views: 4K

I How Do Inhomogeneities in Matter Affect Cosmic Evolution and Backreaction?

Mar 15, 2021 · Replies 10 · Mar 17, 2021

Replies: 10

Views: 1K

I Questions about Isotropy in Our Universe and Implications

Mar 11, 2021 · Replies 6 · Mar 12, 2021

Replies: 6

Views: 1K

I How to compute the expansion of this congruence?

Feb 27, 2021 · Replies 7 · Feb 28, 2021

Replies: 7

Views: 1K

I What is the current status of the Hubble-tension?

Jan 4, 2021 · Replies 8 · Feb 26, 2021

Replies: 8

Views: 2K

I When was the matter density equal to the vacuum energy density?

Feb 20, 2021 · Replies 2 · Feb 20, 2021

Replies: 2

Views: 2K

A What are the parameters that are the same in CMB data for multiple models?

Feb 14, 2021 · Replies 8 · Feb 20, 2021

Replies: 8

Views: 1K

I What are the key characteristics of rivals to inflation in cosmology?

Jan 13, 2021 · Replies 14 · Feb 16, 2021

Replies: 14

Views: 2K

B How can the Observable Universe be a closed system?

Jan 30, 2021 · Replies 37 · Feb 2, 2021

2

Replies: 37

Views: 6K

A Combining 2 probes in order to increase Figure of Merit

Feb 1, 2021 · Replies 5 · Feb 2, 2021

Replies: 5

Views: 1K

B The Universe is now closed and curved?

Nov 4, 2019 · Replies 26 · Jan 28, 2021

Replies: 26

Views: 4K

B Does Dark Matter Have a Periodic Table?

Jan 25, 2021 · Replies 12 · Jan 25, 2021

Replies: 12

Views: 2K

I Are masers orbiting black holes a reliable standard ruler in cosmology?

Jan 20, 2021 · Replies 11 · Jan 21, 2021

Replies: 11

Views: 2K

I Is dark energy pushing or is it a mirror concept of gravity?

Jan 16, 2021 · Replies 31 · Jan 19, 2021

2

Replies: 31

Views: 4K

I Accelerating Universe and spherical distribution of matter

Jan 7, 2021 · Replies 9 · Jan 10, 2021

Replies: 9

Views: 1K

B Did the Big Bang expand faster than light?

Dec 28, 2020 · Replies 26 · Jan 6, 2021

Replies: 26

Views: 4K

B Can We See Beyond the Voids in Our Universe?

Dec 31, 2020 · Replies 14 · Jan 5, 2021

Replies: 14

Views: 2K

A What is the jerk parameter in terms of the Density parameters?

Dec 23, 2020 · Replies 1 · Dec 23, 2020

Replies: 1

Views: 1K

B The infinite and the infinitesimal

Dec 19, 2020 · Replies 10 · Dec 21, 2020

Replies: 10

Views: 3K

B An interesting consequence of the closedness of the Cosmos

Dec 11, 2020 · Replies 13 · Dec 14, 2020

Replies: 13

Views: 2K

A Black Holes Formalism: Overview of Misner Sharp Mass

Dec 2, 2020 · Replies 13 · Dec 14, 2020

Replies: 13

Views: 3K

B How can dark energy comprise 74% of the Universe?

Dec 9, 2020 · Replies 36 · Dec 12, 2020

2

Replies: 36

Views: 4K

I Is Scale Factor Continuity and Differentiability Necessary?

Dec 11, 2020 · Replies 6 · Dec 11, 2020

Replies: 6

Views: 1K

I Laws of physics from initial conditions?

Nov 27, 2020 · Replies 5 · Dec 9, 2020

Replies: 5

Views: 2K

I Is there any inflationary model without a fundamental theory?

Dec 5, 2020 · Replies 2 · Dec 5, 2020

Replies: 2

Views: 2K

I Is there a Friedmann equation form with inflation?

Nov 27, 2020 · Replies 2 · Nov 27, 2020

Replies: 2

Views: 1K

B Did the Big Bang follow multiple bangs? How did matter come to collide?

Nov 11, 2020 · Replies 43 · Nov 23, 2020

2

Replies: 43

Views: 5K

I Change law of gravitation to remove dark energy and dark matter

Nov 21, 2020 · Replies 13 · Nov 21, 2020

Replies: 13

Views: 2K

I Contradictory Cosmological Values: Crisis for Cosmology?

Sep 1, 2020 · Replies 14 · Nov 16, 2020

Replies: 14

Views: 3K

I What is the best current value for Omega_r?

Nov 3, 2020 · Replies 22 · Nov 10, 2020

Replies: 22

Views: 3K

A An article on Big Bang theory contradictions

Nov 10, 2020 · Replies 3 · Nov 10, 2020

Replies: 3

Views: 2K

I Question about spacetime singularities

Nov 9, 2020 · Replies 1 · Nov 9, 2020

Replies: 1

Views: 1K

B How does the cosmological constant affect gravitational collapse?

Nov 8, 2020 · Replies 2 · Nov 9, 2020

Replies: 2

Views: 2K

B Dark matter interactions other than gravity

Nov 3, 2020 · Replies 12 · Nov 5, 2020

Replies: 12

Views: 3K

I Cosmology Comoving coordinates and observers

Nov 4, 2020 · Replies 4 · Nov 4, 2020

Replies: 4

Views: 3K

I Demonstration of comoving volume between 2 redshifts

Feb 9, 2020 · Replies 59 · Nov 3, 2020

2

Replies: 59

Views: 8K

I Big Crunch and the Universe's shape

Nov 3, 2020 · Replies 1 · Nov 3, 2020

Replies: 1

Views: 1K

I How does the Singularity produce all the diverse matter in the universe?

Nov 2, 2020 · Replies 9 · Nov 2, 2020

Replies: 9

Views: 2K

I Does Hawking Radiation Cause Black Holes to Evaporate?

Oct 31, 2020 · Replies 24 · Oct 31, 2020

Replies: 24

Views: 3K

B New theory of the early Universe

Oct 24, 2020 · Replies 1 · Oct 26, 2020

Replies: 1

Views: 1K

B Question about calculating the density of the Universe

Oct 15, 2020 · Replies 2 · Oct 21, 2020

Replies: 2

Views: 2K

B Difference between an Einstein frame and a String frame?

Oct 19, 2020 · Replies 4 · Oct 19, 2020

Replies: 4

Views: 3K

A BGV-theorem and Penrose's Conformal Cyclic Cosmology

Oct 11, 2020 · Replies 5 · Oct 18, 2020

Replies: 5

Views: 3K

I Schwartzchild radius and the Big Bang

Oct 14, 2020 · Replies 13 · Oct 15, 2020

Replies: 13

Views: 3K

I Reason for matter rather than antimatter?

Oct 9, 2020 · Replies 4 · Oct 12, 2020

Replies: 4

Views: 1K

I What "space" is used in defining cosmological distributions?

Oct 9, 2020 · Replies 1 · Oct 9, 2020

Replies: 1

Views: 1K

I Qs re the behavior of atoms after decoupling completed

Oct 7, 2020 · Replies 1 · Oct 7, 2020

Replies: 1

Views: 2K

A Confusion in Angular diameter distance

Oct 5, 2020 · Replies 4 · Oct 5, 2020

Replies: 4

Views: 2K

A Are topological defects such as domain walls really discontinuous?

Sep 23, 2020 · Replies 2 · Oct 3, 2020

Replies: 2

Views: 1K

I What is the density of hydrogen atoms in the Universe?

Sep 30, 2020 · Replies 3 · Sep 30, 2020

Replies: 3

Views: 2K

A Experimental test of shrinking matter theory?

Sep 17, 2020 · Replies 42 · Sep 21, 2020

2

Replies: 42

Views: 4K

I Multiple Universes Coming into Contact

Sep 19, 2020 · Replies 2 · Sep 19, 2020

Replies: 2

Views: 1K

B Is the Big Bang only about the observable Universe?

Aug 23, 2020 · Replies 6 · Sep 16, 2020

Replies: 6

Views: 3K

I New Hubble Paper On Lensing In Galactic Clusters

Sep 11, 2020 · Replies 2 · Sep 13, 2020

Replies: 2

Views: 2K

B Questions about the Curvaton particle

Sep 10, 2020 · Replies 5 · Sep 13, 2020

Replies: 5

Views: 1K

B Finding the present day distance to a galaxy

Sep 11, 2020 · Replies 1 · Sep 11, 2020

Replies: 1

Views: 1K

A Accelerated Hubble expansion -- Is the second derivative positive?

Aug 31, 2020 · Replies 17 · Sep 7, 2020

Replies: 17

Views: 4K

I Effect of Dark Matter on fast moving bodies

Aug 31, 2020 · Replies 10 · Sep 5, 2020

Replies: 10

Views: 2K

B Question about the size of atoms as time progressed

Jul 5, 2020 · Replies 14 · Sep 3, 2020

Replies: 14

Views: 2K

Cosmology

Cosmology is the scientific study of the large-scale structure, origin, evolution, and ultimate fate of the universe. It seeks to understand the fundamental nature of the cosmos, including the distribution of galaxies, dark matter, dark energy, and the overall geometry of space-time. Cosmologists explore the early moments of the universe, moments after the Big Bang, and employ various observational tools, such as telescopes and satellites, to gather data that informs our understanding of cosmic evolution.

Key concepts in cosmology include the expansion of the universe, cosmic microwave background radiation, and the formation of galaxies and large-scale structures. It is a field that intersects with physics, astronomy, and astrophysics, providing insights into the vast and intricate tapestry of the cosmos.

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