Erik Verlinde says no need for Dark Matter and Gravity is emergent

a reply to: greenreflections


Actually that is my opinion.

a reply to: Kashai

You offered earlier that photons orbit black holes but if they were organized a certain way would that make a difference?

May be. My conclusion about light orbiting black hole was based on assumption that photon has zero mass and zero size.
As a result it will stay on 'permanent' orbit simply by following spatial path. By orbit I meant a layer where light is in circular motion (loops), where there is neither recess nor decay for that orbit.

a reply to: greenreflections

Do photons have physical mass?

Photons have mass.  Photons have momentum.  Photons have energy.  Photons are affected by a gravitation field and follow a curved  path called a geodesic. (A geodesic i… (MORE)]/ex]

Is there any experimental evidence that the photon has zero rest mass?

Alternative theories of the photon include a term that behaves like a mass, and this gives rise to the very advanced idea of a "massive photon".  If the rest mass of the photon were non-zero, the theory of quantum electrodynamics would be "in trouble" primarily through loss of gauge invariance, which would make it non-renormalisable; also, charge conservation would no longer be absolutely guaranteed, as it is if photons have zero rest mass.  But regardless of what any theory might predict, it is still necessary to check this prediction by doing an experiment.

It is almost certainly impossible to do any experiment that would establish the photon rest mass to be exactly zero.  The best we can hope to do is place limits on it.  A non-zero rest mass would introduce a small damping factor in the inverse square Coulomb law of electrostatic forces.  That means the electrostatic force would be weaker over very large distances.

Likewise, the behavior of static magnetic fields would be modified.  An upper limit to the photon mass can be inferred through satellite measurements of planetary magnetic fields.  The Charge Composition Explorer spacecraft was used to derive an upper limit of 6 × 10−16 eV with high certainty.  This was slightly improved in 1998 by Roderic Lakes in a laboratory experiment that looked for anomalous forces on a Cavendish balance.  The new limit is 7 × 10−17 eV.  Studies of galactic magnetic fields suggest a much better limit of less than 3 × 10−27 eV, but there is some doubt about the validity of this method.

math.ucr.edu...

edit on 11-2-2017 by Kashai because: Added content

Alternative theories of the photon include a term that behaves like a mass, and this gives rise to the very advanced idea of a "massive photon". 

Further...

www.princeton.edu...

a reply to: Kashai

Ok, if mass of photon is proven, what do you offer as a consequence? What exactly does this solve?

There is a recent paper that tests Verlindes Emergent Gravity on observed galactic rotation curves.

And it doesn't look good for EG. It requires considerably different mass distribution between disk and bulge to match the data.

We find that EG is consistent with the data only if we change our fiducial conversions from Spitzer [3.6] luminosity to stellar mass.
...
We conclude that the observed dynamics of disc galaxies pose a significant challenge to EG. While the asymptotic behaviour is correct in the point mass limit, problems appear for galaxies of finite extent

Source: arxiv.org...

a reply to: greenreflections


Can one create a substantive mass just using photons?

This article is from September 18, 1997

A team of 20 physicists from four institutions has literally made something from nothing, creating particles of matter from ordinary light for the first time. The experiment was carried out at the Stanford Linear Accelerator Center (SLAC) by scientists and students from the University of Rochester, Princeton University, the University of Tennessee, and Stanford. The team reported the work in the Sept. 1 issue of Physical Review Letters.

www.sciencedaily.com...

a reply to: Kashai

Can one create a substantive mass just using photons?

May be. I am more interested in nature of gravity, 3D environment forming, possible using number of intersecting 2D energetic planes. String theory is the closest to my line of thought.

a reply to: greenreflections

Strictly speaking, the aim of quantum gravity is only to describe the quantum behavior of the gravitational field and should not be confused with the objective of unifying all fundamental interactions into a single mathematical framework. While any substantial improvement into the present understanding of gravity would aid further work towards unification, study of quantum gravity is a field in its own right with various branches having different approaches to unification. Although some quantum gravity theories, such as string theory, try to unify gravity with the other fundamental forces, others, such as loop quantum gravity, make no such attempt; instead, they make an effort to quantize the gravitational field while it is kept separate from the other forces. A theory of quantum gravity that is also a grand unification of all known interactions is sometimes referred to as The Theory of Everything (TOE).

One of the difficulties of quantum gravity is that quantum gravitational effects are only expected to become apparent near the Planck scale, a scale far smaller in distance (equivalently, far larger in energy) than what is currently accessible at high energy particle accelerators. As a result, quantum gravity is a mainly theoretical enterprise, although there are speculations about how quantum gravitational effects might be observed in existing experiments.[13]

en.wikipedia.org...

Further and same link....

Loop quantum gravity seriously considers general relativity's insight that spacetime is a dynamical field and is therefore a quantum object. Its second idea is that the quantum discreteness that determines the particle-like behavior of other field theories (for instance, the photons of the electromagnetic field) also affects the structure of space.

The main result of loop quantum gravity is the derivation of a granular structure of space at the Planck length. This is derived from following considerations: In the case of electromagnetism, the quantum operator representing the energy of each frequency of the field has a discrete spectrum. Thus the energy of each frequency is quantized, and the quanta are the photons. In the case of gravity, the operators representing the area and the volume of each surface or space region likewise have discrete spectrum. Thus area and volume of any portion of space are also quantized, where the quanta are elementary quanta of space. It follows, then, that spacetime has an elementary quantum granular structure at the Planck scale, which cuts off the ultraviolet infinities of quantum field theory.

The quantum state of spacetime is described in the theory by means of a mathematical structure called spin networks. Spin networks were initially introduced by Roger Penrose in abstract form, and later shown by Carlo Rovelli and Lee Smolin to derive naturally from a non-perturbative quantization of general relativity. Spin networks do not represent quantum states of a field in spacetime: they represent directly quantum states of spacetime.

The theory is based on the reformulation of general relativity known as Ashtekar variables, which represent geometric gravity using mathematical analogues of electric and magnetic fields.[45][46] In the quantum theory, space is represented by a network structure called a spin network, evolving over time in discrete steps.[47][48][49][50]

The dynamics of the theory is today constructed in several versions. One version starts with the canonical quantization of general relativity. The analogue of the Schrödinger equation is a Wheeler–DeWitt equation, which can be defined within the theory.[51] In the covariant, or spinfoam formulation of the theory, the quantum dynamics is obtained via a sum over discrete versions of spacetime, called spinfoams. These represent histories of spin networks.

Again...

Dilation[edit]

Main article: Dilaton

The dilaton made its first appearance in Kaluza–Klein theory, a five-dimensional theory that combined gravitation and electromagnetism. Generally, it appears in string theory. More recently, however, it's become central to the lower-dimensional many-bodied gravity problem[22] based on the field theoretic approach of Roman Jackiw. The impetus arose from the fact that complete analytical solutions for the metric of a covariant N-body system have proven elusive in general relativity. To simplify the problem, the number of dimensions was lowered to (1+1), i.e., one spatial dimension and one temporal dimension. This model problem, known as R=T theory[23] (as opposed to the general G=T theory) was amenable to exact solutions in terms of a generalization of the Lambert W function. It was also found that the field equation governing the dilaton (derived from differential geometry) was the Schrödinger equation and consequently amenable to quantization.[24]

Thus, one had a theory which combined gravity, quantization, and even the electromagnetic interaction, promising ingredients of a fundamental physical theory. It is worth noting that this outcome revealed a previously unknown and already existing natural link between general relativity and quantum mechanics. For some time, a generalization of this theory to (3+1) dimensions was unclear. However, a recent derivation in (3+1) dimensions under the right coordinate conditions yields a formulation similar to the earlier (1+1) namely a dilaton field governed by the logarithmic Schrödinger equation[25] which is seen in condensed matter physics and superfluids. The field equations are indeed amenable to such a generalization (as shown with the inclusion of a one-graviton process[26]) and yield the correct Newtonian limit in d dimensions but only if a dilaton is included. Furthermore, the results become even more tantalizing in view of the apparent resemblance between the dilaton and the Higgs boson.[27] However, more experimentation is needed to resolve the relationship between these two particles. Since this theory can combine gravitational, electromagnetic and quantum effects, their coupling could potentially lead to a means of vindicating the theory, through cosmology and even, perhaps, experimentally.

originally posted by: Kashai
a reply to: Kashai


One way to understand what is explained is that in so far as Gravity having only one charge presents that Anti- Gravity is impossible.

Sure we can find alternative way to leave a planet but that is not anti-gravity which in scope would be like the direct opposite of gravity in translation.

Such a potential in reality does not exist as far as we know.

That's what I am thinking.
In reality, there should be no term as 'anti gravity'. People who say energy can be negative, will tell us 'anti' gravity is possible. Energy by definition is presence of something. To say 'zero energy' or value of energy presence is meaningful, but to say 'negative energy' is meaningless.

There is nothing below zero. Even zero cannot be achieved. 'Zero' while being common mathematical value does not exist in nature, just like an infinity. Zero and infinity as two impossibilities alone, hint on the two unite, to become neutral (original state). Driving motive behind motion could be 'plus' and 'minus' ends trying to meet on cosmic level.




cheers)

a reply to: greenreflections

That's what I am thinking.
In reality, there should be no term as 'anti gravity'. People who say energy can be negative, will tell us 'anti' gravity is possible.

Actually, anti gravity was already 'invented'...it is escape velocity from the surface. )))LOL
Two ways of artificial gravity on board of hypothetical space ship were thought of as well. First one is to move at continues acceleration and as approaching point of destination, continues slowing down.)) That would create some necessary 'g'.
Second way is when in orbit. Say, from my space ship I drop a tether toward Earth. Tether should be long enough to experience stretching due to spatial changes inside gravity 'well'. Those geometrical changes will make flexible tether strong and act as an 'anchor'. Space ship in this scenario will start experiencing centripetal force. It can go faster beyond required orbital velocity never leaving that particular orbit. In this scenario I will feel 'g'.

One member has mentioned artificial gravity while in orbit recently. I just cannot find that post or correct nick spelling...


cheers)