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

Quest to settle riddle over Einstein's theory may soon be over
February 10, 2017

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Albert Einstein
Astronomy experiments could soon test an idea developed by Albert Einstein almost exactly a century ago, scientists say.

Tests using advanced technology could resolve a longstanding puzzle over what is driving the accelerated expansion of the Universe.

Researchers have long sought to determine how the Universe's accelerated expansion is being driven. Calculations in a new study could help to explain whether dark energy- as required by Einstein's theory of general relativity - or a revised theory of gravity are responsible.

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.



Read more at: https://phys.org/news/2017-02-quest-riddle-einstein-theory.html#jCp

 

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http://www.sciencedirect.com/science/article/pii/S0370269316307948

Challenges to self-acceleration in modified gravity from gravitational waves and large-scale structure

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.

 

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Could "dark energy" be "light energy"?
Could the light radiating from all the stars somehow push the universe apart?
I suppose there is not sufficient light energy to account for the observations.
It sure would be satisfying to understand dark energy.
Thanks for posting Paddoboy.
Alex

 

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I'm being serious here so stay with me

I have made the point in other post which in simple terms runs like this

NOTHING

Big Bang or Expansion (pick your flavour)

Everything flying outwards

Birth of the Universe

Expansion continues

Everything at the outer limits of the Bubble Universe is gaining speed

Because it has not experienced any resistance and is still being driven by the energy from the Big Bang

Your all invited when I get the Nobel

OK the last bit I'm not serious - I haven't put a paper in yet

But the rest makes sense to me

 

But there is resistance. It is the mutual gravitational attraction of the universe itself that it trying to pull it back together. Thus as the universe expands, it should be giving up expansion speed for GPE. That means that if the energy content of the Big Bang were a constant, the expansion speed would slow with time (otherwise the energy of the universe would be constantly increasing). The fact that it does not appear to do so, but instead accelerates faster as time goes on means that something else must be going on, and that "something else" is what we have applied the label "Dark energy".

 

Yes I admit I missed that wrinkle

I was only referring to resistance forward of the expansion

However since the expansion appears to be accelerating the gravity pull does not appear to be working at the moment

I am aware calculations have been made to see if there is enough Universe to turn the Big Bang (Expansion) into the Big Crunch (Contraction)

My very unscientific gut (not GUT) feeling goes to expansion for ever

Had not thought of Dark Energy being in the picture

But that sounds a bit dodgy

If you consider Dark Energy is pushing and accelerating the far far away part of the Universe

Where is the opposite reaction and all that pushing?

I'll stay with the initial Big Bang energy still working because of no outside of the Universe resistance

And wasn't there some research indicating the Gravity constant was decreasing?

If true another reason to bet on Expansion for ever

 

A basic conceptual blunder is a 'wrinkle'? The derisive critic elsewhere, ever so kind and gentle towards self here.

The classic lay misconception of BB as a kind of 3D gas explosion into an empty pre-existing infinite expanse.

Nonsense. Gravity is working just fine - at every moment thank you. As to whether it differs substantially from GR, or whether say some extra field accounts for accelerated expansion, is still up for grabs.

Your gut feeling? Nothing to do with likely having previously read dozens upon dozens of articles, posts etc. expressing consensus view it will continue?

Clearly have no grasp of the basic cosmological picture. There cannot be any 'edge' to the universe. Things look the same, on large-scale average, everywhere:
https://en.wikipedia.org/wiki/Copernican_principle

Since there is no outside, 'resistance' must be traced to what's happening on the 'inside'. Covered in previous post.

Was there? Try citing. Much safer to stick with Poe quips. Unfortunately.

 

BECAUSE

I was only referring to resistance forward of the expansion

AND

Because it has not experienced any resistance and is still being driven by the energy from the Big Bang

Prey tell what the Universe IS expanding into?

Jello?

Yes gut feeling

Sure I have read about Big Bang and Expansion alongside Big Crunch and Contraction

My two neurones argue about this but gut says Expansion forever

Yes

Internally

Externally at distance our whole Universe might look like a Galaxy

And if we turn around there might exist the ol MultVerse

Your position is the Universe has no outside?

OK

A Universe resembling a balloon with galaxies on the skin and others suspended inside and this balloon is the only thing in existence because outside of the balloon there is not NOTHING not even NOTHING exist

I'm to lazy to chase up something to cite when by posing the question I have invited someone to look up the information for themselves

Poe was not really designed for quips

Humpty was more the quipper

'`Curiouser and curiouser!' cried Alice as she shot outside the Universe

Sorry Lewis Carroll

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Clearly real hard to shake those classic misconceptions. There is no 'expansion front' for the universe. No edge, beyond which lies some perfect vacuum 'outside'.
And yes there is 'resistance'. Mutual gravitational attraction. In a notionally homogeneous universe gravity doesn't 'point' anywhere, but it's effect is still there - to decelerate expansion. As covered in #5.

No. See my above comment.

Again, there is no outside in any sense of being accessible in principle. Multiverse concept is often picturesquely illustrated as literally 'bubbles within bubbles' and such, but that's simply a crutch to help with a difficult idea. Even if Multiverse concept is true, there is still no way one could even with a magical 'warp drive' affording infinite speed, get to be outside our particular 'bubble universe' and be looking back on it. Always confined within.

It's been the stock standard consensus position of cosmologists for many decades.

The 2D balloon analogy is ok if you don't start erroneously spoiling it by having things inside it. 3D rising raisin-loaf analogy is not really an improvement since it suggests an edge to the 'loaf' i.e. it's outside crust implies by analogy an edge to the universe. Wrong inference. 2D balloon analogy better in that regard - you must remember only movement and distance along the surface is allowed. Then one hopefully sees the point of there being no 'edge' or boundary.

Pardon my deep ignorance.

Yes in Wonderland Alice no doubt could do all of that and much more besides. We are not in Wonderland though. Well not physically.

 

Clearly, I wasted time and effort trying: http://www.sciforums.com/threads/th...the-western-world.158483/page-21#post-3437707

 

Question: If gravity is so predictable, why can we not identify the mechanism that creates gravity? Gravitons? Where and how?

A thought occurred to me and I'd like to hear why the following proposition cannot be true.

I believe that the common interpretation is that massive bodies attract each other.
But the cause for this attraction is still a mystery except for speculative graviton particles.

Suppose that a massive body exerts gravity on spacetime, but instead of attracting between massive bodies, could we consider that each object attracts spacetime itself, causing an increase of spacetime density around each object and thereby creating a partial vacuum between the objects' sphere of influence, which causes spacetime to repair itself by forcing the object closer to each other and filling the partial vacuum.

It seems to me that such a scenario would apply to all four fundamental forces with only the proximity of the particles creating the bonding strength.

Such a scenario does not require a graviton particle, but only a local thinning of spacetime drawing objects together to fill the missing space density.

None of this would affect the observed gravitational behaviors, but it changes the concept of gravitational distortion of spacetime being caused by gravitons, to a lack of geometric density of spacetime itself.

I address this only, because so far the graviton seems to elude detection. Are there gravitons at all and is there no alternate solution available to explain gravity, other than graviton attraction, which sounds contrived to me.

 

That "mechanism" question is literally not required to predict the behavior of gravitational phenomena, just as the color of your mother's KichenAid stand mixer is not required to decide what flavor cake she baked.

 

I understand that, gravitational behavior is well documented. My question was what and how the gravitational properties of each body is transmitted to the other.
IOW what constitutes a gravitational field?

I am aware of two possibilities; warping of spacetime by the actual mass of each object, bending spacetime, and/or the transmission of gravitons, which somehow impart knowledge of gravitational properties to the other body.

 

True, but to bake a cake you have to have flour.

 

This must have been close to the last thread paddoboy started.

I have already predicted in another thread that the only energy transfer event fast enough to escape the event horizon of a pair of black holes merging would be entanglement energy from their cores. Very weak acoustic coupling of those entanglement waves to local protons would make perfect sense.

If that is the case, the events recorded by LIGO have already happened (because entanglement is instantaneous), and it will take the optical detection of those events a considerable time to catch up to the gravity waves.

You would need to be able to resolve images of those merger events BEFORE LIGO detected the chirp to verify if it was detected FTL

The calculations from LIGO of course assumed that gravity waves traveled at the speed of light, as Einstein predicted.

 

Has anyone ever proposed that universal expansion is maintained (and accelerated) by a 'pulling' or 'growing'-type mechanism . . . . something like . . . conversion of pre-exsistent universal energy to mass . . . not unlike (2-D analogy here!!): a field of dry grass burning successively outward - dry grass = energy source . . . burn't grass (carbon/ash) = mass (remember . . just a 2-D analogy for visualization purposes). Now visualize the analogy as 3-D. (NOTE: I have an unproven hypothesis that describes/illustrates this, but won't post here since it is an 'alternate (to SM) theory' and off-topic for this thread.)

 

I like the clear analogy, with one question.
For grass to burn and turn into matter, shouldn't there be grass in the first place?

However, this picture presents me with a perspective, that as energy travels outward it cools by the absolute zero temperature of nothingness. Is it possible that this cooling can produce physical particles from energy?

Isn't that something like the inflationary epoch where cooling of the initial pure energy waves produced the first massive physical particles. Sorry, but I wanted to post this before I forget. Carry on......

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Could this be tested on Mars?
Create a entangled pair and take one to Mars with a transmitter. Then reverse the spin of the earth particle and within a very short, but relatively very accurate time we should be able to see if the Mars particle reversed its spin also.
As I understand it, this experiment has been conducted on earth, but the distance seems too short for making accurate reading of the behavior of entangled particles at longer distances, such as on Mars. OTOH, trying to observe and compare times of entangled particles over extremely long distances seems impractical, for obvious reasons.

OTOH, if you mean that the energy itself is converted to massive particles, due to the absolute zero temperature of the nothingness.
If particles can form in such a manner, perhaps the universe is not expanding at a faster rate, which is calculated based on speed of *c*.
Now, if a particle were to form it would no longer be able to travel at *c*, thus it would take longer for the return signal to reach the earth. But this longer time would not be due to greater distance traveled at an increased speed, but due to the slowing down of the newly formed particle which is no longer able to travel at *c* and returns at sub-luminal speed, taking longer and giving the appearance of having traveled a longer distance at FTL.
Dang, that does not sound coherent.

Just musing, but if particles can form from cooling during the initial expansion, why could such a thing not be possible at the edges of the expanding universe?

 

"For grass to burn and turn into matter, shouldn't there be grass in the first place? . . . ." I am only utilizing 'grass' (not pot, btw HAHA!!) as an analogy for a pre-existing energy source. That energy source (grass) undergoes a transformation (the grass burns, or transforms) to produce a product (carbon, ash) - the carbon and ash in the analogy are equivalent to the 'mass' are produced from the transformation of energy (as in, m=c^2)/E). IOW, m would = burn products; E would = grass,; and burning would = E ---> mass transform process.

"Isn't that something like the inflationary epoch where cooling . . . ." I suppose so - adiabatic expansion (cooling) would likely be accompanied by loss of latent heat, I think (evaporation, perhaps?). However, I don't think the formation of paticles (mass) from energy (E) is that simple since the production of virtual particles is involved wherein some (majority) of virtual particles must persist (i.e., DON'T auto-anihilate back to E) in order to form 'permanent' observable mass. I visualize a more or less contiguous, uniform (with caveats!) equilibrium pre-universe that is more like an extremely high-energy density field. High-density is probably a requirement since it take a LOT of energy to transform to very little quantity of mass. I estimate the pre-universe energy density to be on the order of 10^160 ergs/cc. Reverse calculation of the energy required to 'create' (via the equivalence principle, E=mc^2), the current (estimated) mass content of the observable universe is 10^60 ergs, or so (assumes all mass is at rest, for simplicity - which it is not). But . . . . I ramble on . . . .

I'm not sure what you mean by pure energy, so I will presume that yor pure energy is the same as mine - an entirely 'pure energy' pre-universe (I use the term pre-universe loosely, since it is difficult to define exactly).

 

Thanks for responding. It seems we're thinking along similar lines (I'm a layman).

My personal identification for the pre-universe state is "a permittive condition", which gets me off the hook by its generalization.

I got the term Pure Energy from David Bohm's *Wholeness and the Implicate Order", where he describes a hierarchy of orders from pure energy with near infinite potential, in which implications form, which are ultimately expressed as reality.

My question to you, do you see this pure energy as residing inside the singularity, or throughout the pre-universe permittive condition?