Quest to settle riddle over Einstein's theory may soon be over

[Jim__]

From phys.org:

…

Einstein's theory, which describes gravity as distortions of space and time, included a mathematical element known as a Cosmological Constant. Einstein originally introduced it to explain a static universe, but discarded his mathematical factor as a blunder after it was discovered that our Universe is expanding.

Research carried out two decades ago, however, showed that this expansion is accelerating, which suggests that Einstein's Constant may still have a part to play in accounting for dark energy. Without dark energy, the acceleration implies a failure of Einstein's theory of gravity across the largest distances in our Universe.

Scientists from the University of Edinburgh have discovered that the puzzle could be resolved by determining the speed of gravity in the cosmos from a study of gravitational waves -space-time ripples propagating through the universe.

The researchers' calculations show that if gravitational waves are found to travel at the speed of light, this would rule out alternative gravity theories, with no dark energy, in support of Einstein's Cosmological Constant. If however, their speed differs from that of light, then Einstein's theory must be revised.

more …

[yodermon]

1. I thought the speed of gravity has already been shown to be the speed of light?

Interesting.

[Jim__]

2. The full paper is available:

Here

My understanding from the abstract is that new measurement would be a confirmation using a different (better?) method. The abstract:

Abstract

With the advent of gravitational-wave astronomy marked by the aLIGO GW150914 and GW151226 observations, a measurement of the cosmological speed of gravity will likely soon be realised. We show that a confirmation of equality to the speed of light as indicated by indirect Galactic observations will have important consequences for a very large class of alternative explanations of the late-time accelerated expansion of our Universe. It will break the dark degeneracy of self-accelerated Horndeski scalar–tensor theories in the large-scale structure that currently limits a rigorous discrimination between acceleration from modified gravity and from a cosmological constant or dark energy. Signatures of a self-acceleration must then manifest in the linear, unscreened cosmological structure. We describe the minimal modification required for self-acceleration with standard gravitational-wave speed and show that its maximum likelihood yields a 3σ poorer fit to cosmological observations compared to a cosmological constant. Hence, equality between the speeds challenges the concept of cosmic acceleration from a genuine scalar–tensor modification of gravity.

[Javaman]

3. bahhh the universe is nothing but a hologram anyway...

There Is Growing Evidence that Our Universe Is a Giant Hologram

https://motherboard.vice.com/en_us/article/there-is-growing-evidence-that-our-universe-is-a-giant-hologram

[ProfessorGAC]

4. Not It's Not, Java!

Out universe is a small locker in a giant train station. Honest, i saw it in a movie.

[Javaman]

5. now you have triggers something in my lizard brain. What movie was that again?

I seem to recall seeing that but I can remember which one it was.

Please don't drive me nuts with trying to guess. LOL

[ProfessorGAC]

6. Men In Black

I think it was the second movie.