**314 dark-energy questions.**

My thought process, where have I gone wrong?
Question 1: There is no gravitational force at the center of the earth is there still gravitational time dilation.
Answer: Yes, there is a potential ...

From the Friedmann equation
$$
H^2=\frac{8\pi G}{3}\rho_m - \frac{kc^2}{a^2} + \frac{\Lambda c^2}{3}.
$$
The dimension of Hubble parameter $H$ is $\frac{1}{\text{time}}$ or $\frac{1}{[T]}$. Therefore, ...

One of the models of dark energy uses the Chaplygin gas (in the generalized version it can even provide a unified model of dark energy and dark matter). What is/are the issue/s with respect to the ...

Imagine you're inside a black hole event horizon. The curvature of spacetime is such that the direction towards the singularity becomes timelike, as reverse movement becomes literally impossible.
How ...

Considering adiabatic process in classical thermodynamics, a normal substance with (positive) pressure must do work on its environment in order for the volume to increase by $ dV $(like pushing the ...

Dark energy is supposed to pull galaxies apart, their gravity not sufficient to escape or even slow the expansion of space. Notable scientists like Dr. Kaku all seem to agree that this results in ...

In Ben Crowell’s comments in these threads
Attractive gravity has negative energy, what about repulsive gravity in the inflation phase?
Does the fact that energy is not conserved in cosmology open ...

If space time is accelerating away from itself everywhere due to dark energy, could this acceleration be the cause of virtual particles, essentially Unruh radiation?

Title speaks for itself.
Dark matter: We see extra attractive force, and we posit that there are particles which create such a force, and use the measure of that force to guess their locations.
Dark ...

There are several cosmological parameters that are more or less of the same order $10^{-60}$ (in Planck unit), namely,
inverse of the age of the universe
$$
\frac{1}{t_0},
$$
Hubble constant
$$
H_0,
$...

We have lots of common everyday experience with positive pressure, the canonical example is a gas.
But other examples of positive pressure are easy to imagine: for instance, a solid that gets ...

In this paper, Dan Hooper of the Fermi National Accelerator Laboratory proposes that advanced aliens might gather stars from other galaxies as a hedge against the dark energy powered expansion of the ...

I have watched VSouce video on gravity. The idea is that gravity pulling it is just lots of mass bending space-time, and natural direction of movement becomes moving towards the mass, and since we ...

The Higgs field has a nonzero vacuum expectation value which contributes to the energy density of the Universe. Energies contribute to the curvature of spacetime and affected by gravitational ...

This may be a very simple question, yet I cannot find an answer that satisfies me. I have read (and please correct me if I am wrong) that the shape of the universe depends on its density. If it has ...

Einstein used the cosmological constant to prevent expansion which he regarded as his greatest blunder. On the other hand, we are saying that the cosmological constant can cause the space expansion to ...

The Universe has always been expanding since the big bang. Today the expansion is accelerating. Has there been any point in time when the expansion of the universe was decelerating? How do we know ...

Energy may affect a mass of an object.
Can dark energy have an impact on a mass of an object?
This question (probably unusual) is prompted by observations of a change in mass (not weight) of large ...

In a closed universe without dark energy, it departs rapidly from flatness and become more curved over time. The expansion of the universe eventually stops and starts to collapses into a big crunch.
...

Today, I was watching the Inexplicable Universe with Neil deGrasse Tyson.
He spoke about Dark Matter, Dark Energy, and then he spoke about Tachyons.
Naively, I thought what if the reason we can't ...

Friedmann equation together with the acceleration equation yield
$\dot{\Omega} = (1+3w) H \Omega (\Omega-1)$.
The Flatness puzzle lies in the fact that $1+3w>0$, but how is this possible in a $\...

My feeling is that no a closed universe can't become open. Under normal evolution according to the Friedman equation the curvature would be more exagerated as time goes on (i.e. a a closed universe ...

I've seen the number a few times (138 x10 to the power of -123) but i haven´t found how scientists calculated it. Max Tegmark mentions it in his research paper about multiverse types as representing ...

Why can't I find anyone mention this online, what causes people to dismiss this theory instantly, so it's not even worth asking?
So "dark gravity" is gravity that is pulling all planets away from ...

I just watched a show on spacetime. In the show they said that the universe's expansion is speeding up instead of slowing down. They said it had to do with dark energy. I was wondering if you could ...

When numerically solving the Friedmann equations for varying cases of an open universe (i.e. $\Omega_0 < 1$) I get the following evolution plots,
where the left plot is for an open universe ...

Why can't the expansion of the universe be thought as the Big Bang itself still in progress? Why do we need to introduce dark energy? The Big Bang was powerful, and that explosion itself could still ...

People hear about dark energy, conceptualize it as a kind of universal repulsion of space itself, and then tend to say that cosmological expansion must be caused by dark energy. Is this correct?

I am not a physicist but this is a question I've been trying to find the answer to for years and no answer I've been given has satisfied me.
It's my understanding that gravity affects all matter all ...

If dark matter consists of some kind of particles that can be described by String Theory, could we be able to describe this kind of strings ("dark strings", i.e, the strings which give rises to dark ...

The 4 generally accepted fundamental forces are the gravitational, electromagnetic, strong nuclear, and weak nuclear forces. How did we come to define these 4 forces as fundamental?
I am interested ...

I can understand that a photon in an expanding universe can be redshifted and lose its energy by its wavelength being stretched from space expansion.
But in the case of inflation and dark energy, it ...

We are told the universe is expanding at anything between 68 and 73km per second, per megaparsec (depending on the places you look) - so by association, the space between us and anything else out ...

Is Dark Energy a particle due to the mass-energy equivalence ($E=mc^2$)? I mean surely something cannot have energy without mass. Hence my question, I've been trying to figure this question out, but ...

Of what I understand, current observations indicate the universe curvature is closely a flat one. This is made possible since adding up the energy densities of regular matter, dark matter and dark ...

According to Quantum Mechanics is it possible that the famous "dark energy" and "zero-point energy" are the same thing that drives the accelerated expansion of the universe or maybe related to each ...

I was thinking about the nature of "dark energy" and the exponential expansion of space. There must be a mechanism for converting energy into space, causing the overall amount of space to grow. This ...

If and when future probe discovers considerable anisotropy at large scales, and that the clustering of masses are aligned to an arbitrary axis, what consequences does it have for the age of the ...

Heat has to go somewhere. Would the light and heat of the stars in the universe amount up to being dark matter ...and dark energy ...
Dark matter would just be small pieces of stuff.
Dark energy ...

I'm currently reading around the topic of dark energy, in particular quintessence, and I understand the idea of freezing and thawing models. In freezing models the potential is shallow at late times, ...

I'm currently reading a review paper on quintessence (https://arxiv.org/abs/1304.1961) and in §3.1 he plots the evolution of the equation of state parameter $w$ with the scale factor $a$. He produces ...

I've been reading a lot trough different articles about dark-matter and dark-energy and how they could explain observations such as the acceleration of the expansion of the universe or the ...

I'm currently reading around the topic of quintessence and other models for dark energy and was hoping someone could explain to me what is meant by slow-roll in terms of quintessence and inflation etc....

Is it possible that M-Theory provides a solution to the mystery of dark matter and dark energy?
The idea of dark matter and dark energy is that there is some inexplicable source affecting our ...

There is not-so-rough evidence that at very large scale the universe is flat. However we
see everywhere that there are local lumps of matter with positive curvature. So i have several questions ...

The Wikipedia page on dark matter mentions that the Planck mission had revealed that in our universe ordinary baryonic matter, dark matter and dark energy are present in the ratio: 4.9%, 26.8% and 68....

What is the origin of dark energy? What determines whether the space has positive or negative pressure?

According to hubble's law of universal expansion, the velocity of a galaxy moving away from ours is directly proportional to the distance between the two. Now velocity is increasing in direction away ...

Pressure cause attractive gravity so we think that negative pressure should be repulsive.
And I've read that negative pressure means constant energy density in an expanding universe which mean energy ...

Christian Henke has recently proposed one approach for the solution of the cosmological constant problem and of the dark matter dynamics:
Quantum vacuum energy in general relativity
Abstract:
The ...

- cosmology
- dark-matter
- space-expansion
- general-relativity
- cosmological-constant
- universe
- gravity
- cosmological-inflation
- energy-conservation
- energy
- astrophysics
- big-bang
- spacetime
- black-holes
- vacuum
- cosmic-microwave-background
- thermodynamics
- experimental-physics
- acceleration
- curvature
- gravitational-waves
- quantum-mechanics
- pressure
- soft-question
- antimatter

- Divide the work
- Why don't bond makers just get loans?
- Why do airliners have to park so accurately?
- When is Houston’s Hurricane Season?
- What's the difference between "vanilla" and "plain" when talking about yogurts?
- Why are airlines so concerned with checked baggage weight?
- Purpose of [ -n "$PS1" ] in bashrc
- Is there a plausible way to build a pipette with medieval technology?
- What does "junk food scoffing masses" mean?
- What would be necessary in order for us to achieve a single stage to orbit, reusable rocket?
- Is a pig-mounted cavalry possible?
- Late 1960's Comic Book with H shaped space ship
- How to handle colleagues who are unwilling to write a bug report?
- Safe for cats to drink from the aquarium?
- How to design an advanced deadman's switch for the "vitality impaired"?
- Is this news article from 1912, essentially explaining climate change, real?
- Is there any etiquette about how to proceed when a technical problem leads to a misplay in an online game?
- Why is storing passwords in version control a bad idea?
- 'The Chosen One' paradox
- Why are escape characters not working when I read from cin?
- Do I draw a card when I resolve an enchantment with Eidolon of Blossoms, Opalescence, and Torpor Orb in play?
- Can you get into a top grad school coming from UT Knox?
- Why is the shape of a hanging chain not a "V"?
- How should I store "unknown" and "missing" values in a variable, while still retaining the difference between "unknown" and "missing"?