[Andeh]

swansont, on 3 January 2011 - 10:38 AM, said:

That sounds wrong to me. They both have mass, and so would induce the same curvature. Photons would, too.

maybe he's not talking about mass curvature, but the theorized curvature that charge causes on 5-d space.

[questionposter]

I keep seeing around these forums and from scientists like Niel DeGrasse that photons curve the fabric of space. How is that? How do photons curve the fabric of space?

This post has been edited by questionposter: 15 January 2012 - 05:11 PM

[Widdekind]

questionposter, on 15 January 2012 - 03:20 PM, said:

I keep seeing around these forums and from scientists like Niel DeGrasse that photons curve the fabric of space. How is that? How do photons curve the fabric of space?

I understand, that according to GR theory, all mass-and-energy curves the fabric of space-time, i.e. "the fabric of space-time perceives all matter & energy in the same way", or "everything is effectively a photon to space-time".

[questionposter]

Widdekind, on 16 January 2012 - 03:01 PM, said:

I understand, that according to GR theory, all mass-and-energy curves the fabric of space-time, i.e. "the fabric of space-time perceives all matter & energy in the same way", or "everything is effectively a photon to space-time".

So energy or photons distorts the fabric of space even though they doesn't have mass? What's the point of having mass then? Mass then? Doesn't that pretty much disprove the existence of mass if photons can distort the fabric of space without some sort of "higg's boson" or "mass causing particle"? How could force carriers themselves emit force carrier particles?

This post has been edited by questionposter: 16 January 2012 - 10:39 PM

[IM Egdall]

questionposter, on 16 January 2012 - 10:38 PM, said:

So energy or photons distorts the fabric of space even though they doesn't have mass? What's the point of having mass then? Mass then? Doesn't that pretty much disprove the existence of mass if photons can distort the fabric of space without some sort of "higg's boson" or "mass causing particle"? How could force carriers themselves emit force carrier particles?

It all comes from E=mc^2. Mass and energy are equivalent. They both produce the same physical effects. Such as producing gravity (spacetime curvature).

So massless particles such as photons are a source of spacetime curvature -- they distort, bend, warp space and time just like particles with mass do. In addition, photons have momentum and inertia, just like particles with mass do.

[swansont]

questionposter, on 16 January 2012 - 10:38 PM, said:

So energy or photons distorts the fabric of space even though they doesn't have mass? What's the point of having mass then? Mass then? Doesn't that pretty much disprove the existence of mass if photons can distort the fabric of space without some sort of "higg's boson" or "mass causing particle"? How could force carriers themselves emit force carrier particles?

In GR, gravity is not a force. GR is also quite separate from the standard model, so the Higgs really doesn't come into play.

[IM Egdall]

As I understand it, if not for the Higgs field, all particles would travel at the speed of light. Most particles, however, do interact with the Higgs, so gain mass (like electrons and quarks). And (I'm not totally sure of this), the faster these particles go, the more they interact with the Higgs field. So they become more and more massive and cannot achieve the speed of light.

Some particles (photons, gluons, and the yet to be detected gravitons) do not interact wth the Higgs field, so are massless and travel at the speed of light.

This post has been edited by IM Egdall: 17 January 2012 - 05:38 PM

[questionposter]

..

This post has been edited by questionposter: 18 January 2012 - 02:07 AM

[Widdekind]

questionposter, on 16 January 2012 - 10:38 PM, said:

How could force carriers themselves emit force carrier particles?

gluons are the force-carriers, of the Strong interaction. gluons carry Strong "color" charge, and so can generate more, of the very field, that they mediate. (imagine if photons carried electric charge, then they, too, could generate EM fields, even as they propagated them.)

[questionposter]

So in the standard model, how do photons cause gravity then? They don't interact with the Higg's field, yet scientists are still planning on building accelerators that use the gravity of very very high energy photon lasers to accelerate particles.

This post has been edited by questionposter: 19 January 2012 - 12:48 AM

[IM Egdall]

questionposter, on 19 January 2012 - 12:48 AM, said:

So in the standard model, how do photons cause gravity then? They don't interact with the Higg's field, yet scientists are still planning on building accelerators that use the gravity of very very high energy photon lasers to accelerate particles.

You are mixing two theories which are not compatible with each other.

The standard model refers to quantum mechanics. It includes the Higgs field but says nothing about gravity.

Gravity is described in general relativity -- where mass/energy is a source of gravity (which is the warping of space and time or spacetime curvature).

New theories like string theory seek to unite quantum mechanics with gravity. But they are still works in progress.

So for now we are stuck with 1) quantum mechanics with inherent uncertainty in nature and where the Higgs field gives particles their mass, and 2) general relativity with no uncertainty in nature and where mass/energy produces spacetime curvature. They are two separate and distinct views of the universe.

[questionposter]

IM Egdall, on 19 January 2012 - 10:30 PM, said:

You are mixing two theories which are not compatible with each other.

The standard model refers to quantum mechanics. It includes the Higgs field but says nothing about gravity.

Gravity is described in general relativity -- where mass/energy is a source of gravity (which is the warping of space and time or spacetime curvature).

New theories like string theory seek to unite quantum mechanics with gravity. But they are still works in progress.

So for now we are stuck with 1) quantum mechanics with inherent uncertainty in nature and where the Higgs field gives particles their mass, and 2) general relativity with no uncertainty in nature and where mass/energy produces spacetime curvature. They are two separate and distinct views of the universe.

Higg's bosons crown around an object more which in tern increases the distortion in the fabric of space? I can't imagine some hasn't though of that already, so I don't get why exactly gravity can't be explained.

[questionposter]

IM Egdall, on 19 January 2012 - 10:30 PM, said:

You are mixing two theories which are not compatible with each other.

The standard model refers to quantum mechanics. It includes the Higgs field but says nothing about gravity.

Gravity is described in general relativity -- where mass/energy is a source of gravity (which is the warping of space and time or spacetime curvature).

New theories like string theory seek to unite quantum mechanics with gravity. But they are still works in progress.

So for now we are stuck with 1) quantum mechanics with inherent uncertainty in nature and where the Higgs field gives particles their mass, and 2) general relativity with no uncertainty in nature and where mass/energy produces spacetime curvature. They are two separate and distinct views of the universe.

Higg's bosons crown around an object more which in tern increases the distortion in the fabric of space? Like maybe 1 higgs boson = .001 degrees of space curvature? I can't imagine some hasn't though of that already, so I don't get why exactly gravity can't be explained in the standard model.

This post has been edited by questionposter: 20 January 2012 - 12:44 AM

[IM Egdall]

questionposter, on 20 January 2012 - 12:43 AM, said:

Higg's bosons crown around an object more which in tern increases the distortion in the fabric of space? Like maybe 1 higgs boson = .001 degrees of space curvature? I can't imagine some hasn't though of that already, so I don't get why exactly gravity can't be explained in the standard model.

But in general relativity, all particles distort space and time (or spacetime). So in your construct, how do photons, which do not interact with the Higgs field, distort spacetime? In other words, Higg's boson's do not crowd around photons. Yet photons (and allother massless particles) are a source of gravity (distortion of spacetime). So I don't think your interesting idea works.

This post has been edited by IM Egdall: 20 January 2012 - 03:54 PM

[questionposter]

IM Egdall, on 20 January 2012 - 03:50 PM, said:

But in general relativity, all particles distort space and time (or spacetime). So in your construct, how do photons, which do not interact with the Higgs field, distort spacetime? In other words, Higg's boson's do not crowd around photons. Yet photons (and allother massless particles) are a source of gravity (distortion of spacetime). So I don't think your interesting idea works.

So is the answer that the standard model doesn't actually know?

[DrRocket]

swansont, on 4 January 2011 - 10:26 AM, said:

AFAIK, one uses concave or convex to describe it, so it's from a local perspective. Curvature from both particles is concave. It does not cancel.

Concave and convex, with respect to curvature are terms that one typically encounters in calculus. They are not generally used to describe manifolds of dimension >1.

One needs to be a bit careful and precise when using the term curvature in general relativity, and with respect to manifolds in general. It does not necessarily mean what you think it means. The notion of curvature is actually rather sophisticated, and not easily described. First, Riemannian curvature is a tensor and the Einstein tensor of general relativity is derived from it. It has no simple explanation. There are actually several different notions of curvature tensors.

ALL curves are "flat" in the terminology of differential geometry. The usual right circular cylinder is also flat. There is such a thing as a flat torus, and a flat torus is one potential model for the curvature of space in cosmological models.

Also, you are correct in that energy, as well as mass (and in fact pressure and momentum flux) are all part of the stress-energy wich determines the Einstein curvature tensor of general relativity.

You are also correct in that curvature from different particles does not cancel -- and since curvature is a tensor field there is no reason to think that such cancellation is even reasonable, since (remember that general relativity is not a quantum theory) two particles cannot be in the same place.

As a particle and its anti-particle have the same rest mass/energy they enter into the stress -energy tensor in the same way. Also note that the curvature tensor is an invariant, independent of any local reference frame, and hence it is the invariant mass/energy and not the relativistic mass/enrgy that is important in the stress-energy tensor. So, before some asks, no you cannot increase the gravitational pull of something and create a black hole simply by viewing it from a reference frame in which it is moving very fast.

Bottom line -- general relativity relies on differential geometry and other sophisticated mathematical descriptions, that may not conform to one's naive intuitive notions. The only way to really understand GR is to invest the necessary time and intellectual capital to understand it in the mathematical framework in which it is formulated. Just Euclid tole told King Ptolemy with respect to geometry, "There is no royal road to general relativity."

[Widdekind]

DrRocket, on 21 January 2012 - 05:56 AM, said:

... energy, as well as mass (and in fact pressure and momentum flux) are all part of the stress-energy which determines the Einstein curvature tensor of general relativity....

the curvature tensor is an invariant, independent of any local reference frame, and hence it is the invariant mass/energy and not the relativistic mass/energy that is important in the stress-energy tensor. So, before some asks, no you cannot increase the gravitational pull of something and create a black hole simply by viewing it from a reference frame in which it is moving very fast.

I do not understand -- "momentum flux" is an input, into the SET; yet "relativistic energy" is not ? I understand, that p₄² = E² - p² = m² (normalized units). So, m² is an input; and p is an input; but not E ? Momentum flux is "invariant", due to time dilation effects ?