Is it possible that the universe could be eternal??...

[Jehanne]

The cosmological constant corresponds to a non-zero vacuum energy, which causes an acceleration in the expansion, and the total of this energy is integrated over the (increasing) volume of the universe.  Money for nothing and chicks for free.

Once again, the problem is that energy is NOT a scalar quantity. It is one component of the four-dimensional energy-momentum vector. As such, it simply doesn't have a well-defined value at each point. Even observers moving at different speeds will measure the energy of an event as different. For a flat spacetime, this can be resolved frame-by-frame. When curvature effects are also brought in as well, you can't even make a common frame of reference at different points.

In the case of dark energy (old school, the cosmological constant), the easiest local frame to use is the co-moving frame. And, in that frame, it represents a type of energy density of the vacuum. But that doesn't allow to 'integrate over the volume' to get a meaningful answer.

Sorry. It was a good idea, but the details simply don't work that way.

Do you think that Dark Energy is a constant? If not, maybe it will reverse and become attractive??

[polymath257]

Once again, the problem is that energy is NOT a scalar quantity. It is one component of the four-dimensional energy-momentum vector. As such, it simply doesn't have a well-defined value at each point. Even observers moving at different speeds will measure the energy of an event as different. For a flat spacetime, this can be resolved frame-by-frame. When curvature effects are also brought in as well, you can't even make a common frame of reference at different points.

In the case of dark energy (old school, the cosmological constant), the easiest local frame to use is the co-moving frame. And, in that frame, it represents a type of energy density of the vacuum. But that doesn't allow to 'integrate over the volume' to get a meaningful answer.

Sorry. It was a good idea, but the details simply don't work that way.

Do you think that Dark Energy is a constant?  If not, maybe it will reverse and become attractive??

Without a good theory of quantum gravity, we simply don't even have a good explanation for the cosmological constant at all. It's been said that the prediction for the value was 'only' off by 120 *orders of magnitude*.

In other words, nobody has any real idea.

[LinuxGal]

Do you think that Dark Energy is a constant?  If not, maybe it will reverse and become attractive??

Without a good theory of quantum gravity, we simply don't even have a good explanation for the cosmological constant at all. It's been said that the prediction for the value was 'only' off by 120 *orders of magnitude*.

In other words, nobody has any real idea.

The toolkit for quantizing classical forces doesn't work with gravitons because they are not perturbatively renormalizable (I know you know that). Superstring theory gave it a shot but we're not seeing even the lightest SUSY particles at the LHC.  Loop Quantum Gravity made a prediction that never materialized experimentally (c being to a small degree dependent on photon wavelength).  The best hope for even demonstrating gravity is quantum at all is by looking at big molecules in superposition but we're not there yet.

All that said, why do we seek an "explanation" for a constant?  No one explained the magnitude of G or c or h bar, they just read it off the dial.

[polymath257]

Without a good theory of quantum gravity, we simply don't even have a good explanation for the cosmological constant at all. It's been said that the prediction for the value was 'only' off by 120 *orders of magnitude*.

In other words, nobody has any real idea.

The toolkit for quantizing classical forces doesn't work with gravitons because they are not perturbatively renormalizable (I know you know that). Superstring theory gave it a shot but we're not seeing even the lightest SUSY particles at the LHC.  Loop Quantum Gravity made a prediction that never materialized experimentally (c being to a small degree dependent on photon wavelength).  The best hope for even demonstrating gravity is quantum at all is by looking at big molecules in superposition but we're not there yet.

All that said, why do we seek an "explanation" for a constant?  No one explained the magnitude of G or c or h bar, they just read it off the dial.

Much care is needed here. There be dragons.

Yes, we frequently explain constants: first, the constant decay rate of a neutron, or the mass of a proton. The problem is *which* constants to explain and which to consider fundamental.

Second, G,c,h,, etc are actually NOT the fundamental constants! We know because their values are unit dependent. Instead, there are constructs like the fine-structure constant, e^2/hc, which are the same in every (rational) system of units.

Third, there is a very good reason to expect an explanation for the cosmological constant. As an 'energy density of a vacuum', it is easy to guess it should be the value of the 'zero point energy' of all the different particle types. That would be the same for every unit of volume and qualify as an energy density of space.

The problem is that when this calculation is done, it gives a result that is 120 orders of magnitude off the actual result. It has been called the worst theoretical prediction ever made. Even more, it would be easier to 'explain' a cosmological constant that is equal to 0. Anything else requires amazing cancellation to happen: almost, but not quite complete.

And that is why a quantum theory of gravity is thought to be required to explain it. But yes, at this point, it is 'read off the dial' and put into the equations. Well, except for those models that allow it (require it) to change over time.

[snowtracks]

For millennia, the first two verses of Genesis were thought to be only poetic. However, they are shown to be scientific in recent years. Verse 1 - The Universe has been determined to have a beginning (Ref: the space-time theorems) as shown conclusively by authors George Ellis, Roger Penrose, and Steven Hawking in the early 70’s that the 4 dimensions can be traced back to point of singularity (one dimension).

Genesis 1: 2 Now the earth was formless and empty, darkness was over the surface of the deep, and the Spirit of God was hovering over the waters.*
The Earth started as a water world that subsequently lost most of the water by the collision of Theia Mars-size planet that also formed the Moon from the shattered Earth/Theia material**.

**Oct 4, 2022, NASA - Collision May Have Formed the Moon in Mere Hours, Simulations Reveal    Billions of years ago, a version of our Earth that looks very different than the one we live on today was hit by an object about the size of Mars, called Theia – and out of that collision the Moon was formed. How exactly that formation occurred is a scientific puzzle researchers have studied for decades, without a conclusive answer.
Most theories claim the Moon formed out of the debris of this collision, coalescing in orbit over months or years. A new simulation puts forth a different theory – the Moon may have formed immediately, in a matter of hours, when material from the Earth and Theia was launched directly into orbit after the impact.

[Jehanne]

For millennia, the first two verses of Genesis were thought to be only poetic. However, they are shown to be scientific in recent years. Verse 1 - The Universe has been determined to have a beginning (Ref: the space-time theorems) as shown conclusively by authors George Ellis, Roger Penrose, and Steven Hawking in the early 70’s that the 4 dimensions can be traced back to point of singularity (one dimension).

Nope. A singularity is zero dimensions, and, no, there is no mathematical proof that the Universe had a beginning.

[Anomalocaris]

For millennia, the first two verses of Genesis were thought to be only poetic. However, they are shown to be scientific in recent years. Verse 1 - The Universe has been determined to have a beginning (Ref: the space-time theorems) as shown conclusively by authors George Ellis, Roger Penrose, and Steven Hawking in the early 70’s that the 4 dimensions can be traced back to point of singularity (one dimension).

Genesis 1: 2 Now the earth was formless and empty, darkness was over the surface of the deep, and the Spirit of God was hovering over the waters.*
The Earth started as a water world that subsequently lost most of the water by the collision of Theia Mars-size planet that also formed the Moon from the shattered Earth/Theia material**.

**Oct 4, 2022, NASA - Collision May Have Formed the Moon in Mere Hours, Simulations Reveal    Billions of years ago, a version of our Earth that looks very different than the one we live on today was hit by an object about the size of Mars, called Theia – and out of that collision the Moon was formed. How exactly that formation occurred is a scientific puzzle researchers have studied for decades, without a conclusive answer.
Most theories claim the Moon formed out of the debris of this collision, coalescing in orbit over months or years. A new simulation puts forth a different theory – the Moon may have formed immediately, in a matter of hours, when material from the Earth and Theia was launched directly into orbit after the impact.

You do realize a person so confused and muddle headed as to think faith is somehow qualified to play any role whatsoever in understanding reality is uniquely unqualified to interpret the implications of scientific discovery based on rigorous assessment of material evidence. Right?

[The Architect Of Fate]

Also, nothing in science says the universe had a beginning in fact Steven Hawkings has said the opposite that there was no single moment of creation. Roger Penrose has argued for a universe before ours and George Ellis has made it clear we can't know if the universe had a beginning so name-dropping physics without understanding their writing makes you look silly. Also, the earth wasn't formless when the cataclysm made the moon it was the same shape it is now. Stop misusing science to push nonsense.

[Jehanne]

Also, nothing in science says the universe had a beginning and the earth wasn't formless it was as much an elongated spheroid as it is now.

Our Earth is 4.543 billion years old; the Universe (or, its latest incarceration) is 13.7 billion years old. The Genesis account has the Earth there from the very beginning.

[Nay_Sayer]

For millennia, the first two verses of Genesis were thought to be only poetic. However, they are shown to be scientific in recent years. Verse 1 - The Universe has been determined to have a beginning (Ref: the space-time theorems) as shown conclusively by authors George Ellis, Roger Penrose, and Steven Hawking in the early 70’s that the 4 dimensions can be traced back to point of singularity (one dimension).

Genesis 1: 2 Now the earth was formless and empty, darkness was over the surface of the deep, and the Spirit of God was hovering over the waters.*
The Earth started as a water world that subsequently lost most of the water by the collision of Theia Mars-size planet that also formed the Moon from the shattered Earth/Theia material**.

**Oct 4, 2022, NASA - Collision May Have Formed the Moon in Mere Hours, Simulations Reveal    Billions of years ago, a version of our Earth that looks very different than the one we live on today was hit by an object about the size of Mars, called Theia – and out of that collision the Moon was formed. How exactly that formation occurred is a scientific puzzle researchers have studied for decades, without a conclusive answer.
Most theories claim the Moon formed out of the debris of this collision, coalescing in orbit over months or years. A new simulation puts forth a different theory – the Moon may have formed immediately, in a matter of hours, when material from the Earth and Theia was launched directly into orbit after the impact.

0/10 troll. Let the adults talk.