Don't quite understand how gravity affects space/time

[EWright]

I've seen a million times the example of a ball on the trampoline and how it deflects the fabric of space. I understand this perfectly, but only because it is happening in an environment with gravity: ie. the ball "falls" into the fabric, stretching it. But what happens when there is no source of gravity (besides the ball)? The ball "falling" doesn't make sense. Also, there must be more than one deflection or dimple in the fabric of space/time because orbiting objects do not need to follow the same plane - so basically there are an infinite amount of deflections at all angles. When I try to imagine this I picture a sphere surrounding the ball which doesn't make sense either.

 

Here is a related question: If the fabric of space/time deflects like a ball on a trampoline, then if you were to shine a light directly towards the center of the ball, won't the light curve towards the edge of the ball as it enters the deflection?

 

Guido, instead of a trampoline try thinking of this as similar (in a reverse sort of way) to the effects a rubber ball would experience if submerged deep in the ocean, under a lot of pressure from the surrounding water. Think of increased depth as increased gravity or increased proximity to a massive body. The more this increases, the more force there is on the object (basically). This doesn't address orbits, but it may help you wrap your mind around the 3-dimensional warpage of space around massive bodies.

 

Also, you refer to the ball on the trampoline as deflecting the fabric of space. Instead, think of it as attracting the fabric of space, but not being able to tear it if you're thinking of such things as stars (as opposed to a black hole, which you could essentially consider a tear). In the same way, don't think of the ball as falling... it is what causes the falling (talking a sun here, as opposed to a planet), so think of the fabric of space falling toward *it*.

 

Similarly, the planet in orbit is falling *around* the sun because of the sun's pull. However, it does so at a speed that balances its outward momentum to the suns attraction. If you shoot a cannon ball from the ground it will travel a certain distance. If you shoot it from a mountain top with increased force, it will travel further. If you get high enough and shoot it with the right amount of force, it will go all the way around the earth and back where it started. Its still falling, but it never lands, it just keeps circling, and is thus orbiting the earth. This is basically what all satallites and planets do... they fall *around* the object they are orbiting, but they are essentially falling. Think of all the planets' planes as verticle instead of horizontal, as they're commonly portrayed, since there is no up or down in space you can do this.

[Harry Costas]

Hello TheFaithfulStone

 

Thank you for the terms.

 

"degenerate matter," not Plasma.

 

Ok we are talking of terms.

 

Is this degenrate matter the fifth form of matter. Or is there more

 

we have

Gas, liquid, solids, plasma.

[Harry Costas]

Hello all

 

Ultra dense Plasma matter

 

http://plasmadictionary.llnl.gov/terms.lasso?page=list&ABC=Q

Term: Quark-gluon plasma

Definition:

"A state of matter in which quarks and gluons, the fundamental constituents of matter, are no longer confined within the dimensions of the nucleon, but free to move around over a volume in which a high enough temperature and/or density prevails. This type of plasma has recently, 2/2000, been observed indirectly by the European laboratory for particle physics, CERN. These plasmas result in effective quark masses which are much larger than the actual masses. Calculations for the transition temperature to this new state give values between 140 and 180 MeV. This is more than 10,000 times the nominal fusion plasma temperature of 10keV. 150 MeV is the characteristic energy of a particle in a plasma at roughly 1.5 trillion Kelvin. This corresponds to an energy density in the neighborhood of seven times that of nuclear matter. Temperatures and energy densities above these values existed in the early universe during the first few microseconds after the Big Bang. "

 

 

http://columbia-physics.net/faculty/gyulassy_main.htm

 

Professor: Miklos Gyulassy

 

Research

quote:"I head the nuclear theory group at Columbia. Our work concentrates on the physics of ultra-dense nuclear matter, called the quark-gluon plasma. Current experiments at the Relativistic Heavy Ion Collider RHIC at BNL require the development of detailed parton/ hadron transport theory in order to interpret the data and to test specific signatures that can reveal the physical properties of this new state of matter. We have developed new techniques to solve ultra-relativistic non-linear Boltzmann equations and relativistic hydrodynamics to study collective flow signatures, such as elliptic transverse flow at RHIC. In addition, these transport models are used to predict pion interferometry correlations that probe the global freeze-out space-time geometry of high energy nuclear reactions. Recently we concentrate on the problem of non-abelian radiative energy loss and its application as a novel tomographic tool to study the density evolution in the expanding gluon plasma on times scales ~10^-23 sec. We predicted that high transverse momentum jets of hadrons produced in nuclear reactions should be strongly quenched by radiative energy loss induced by the high opacity of the produced plasma. This prediction has been recently confirmed by the PHENIX and STAR experiments at RHIC, and we have deduced from the quenching pattern that gluon densities about 100 times greater than in ground state nuclei have been attained in Au+Au reactions at Ecm = 200 AGeV. At such high densities matter is predicted via lattice QCD to be in the deconfined phase. We continue to refine and extend the theory of jet tomography in order to predict the quenching pattern of heavy quarks as well as high pT correlations of monojets. Another area of interest is the dynamics of baryon number transport and hyperonization at RHIC. Preliminary data provide possible evidence of novel topological gluon junction dynamics that we first tested on data at lower SPS/CERN energies."

[Tormod]

Just a little on the anal side there Tormod, my friend.

 

:hyper:

 

The letter c is designated to the speed of light precisely because of its constant velocity.

 

You are mistaken. c is the speed of light in a vacuum, which is constant. The speed of light itself is not constant but has a maximum speed limit, which is c. Thus c is NOT used to designate the speed of light "in general" but particularly the speed of light in a vacuum.

 

Granted, it can be found to travel at slower speeds under the conditions you mention, but I think you caught his drift. I don't imagine everyone in science who refers to the constant speed of light adds a disclaimer to account for these other conditions.

 

His drift was that the speed of light is constant no matter what it travels through. This is wrong.

 

One could also argue that your statement about the usage of c in reference to E=mc^2 here is incomplete as well.

 

No, because here c is *specifically* interpreted as the speed of light in vacuum, per the official definition of c:

 

http://physics.nist.gov/cgi-bin/cuu/Value?c

 

Stop picking bones while there's still meat left on the chicken.

[Tormod]

Hello all

 

Ultra dense Plasma matter

 

Yes, but what does it have to do with black holes?

[Kayra]

Well, that's called "degenerate matter," not Plasma.

 

TFS

 

So this is the stuff Racoon is made of?

[EWright]

:confused:

 

 

 

You are mistaken. c is the speed of light in a vacuum, which is constant. The speed of light itself is not constant but has a maximum speed limit, which is c. Thus c is NOT used to designate the speed of light "in general" but particularly the speed of light in a vacuum.

 

 

 

His drift was that the speed of light is constant no matter what it travels through. This is wrong.

 

 

 

No, because here c is *specifically* interpreted as the speed of light in vacuum, per the official definition of c:

 

http://physics.nist.gov/cgi-bin/cuu/Value?c

 

Stop picking bones while there's still meat left on the chicken.

 

When you respond to portions of my text, you are taking the initial parts out of context. I already acknowledged your points. You then respond to this acknowledgement by telling me what *his* drift was. You do so to defend your previous post because what I'm saying is true. I also find it discouraging that you seem to rip on his ideas, instead of offering more constructive advice and direction, so that he might come to better understand the topic.

[Tormod]

When you respond to portions of my text, you are taking the initial parts out of context.

 

Why are you so hell-bent on making me look stupid here?

 

You then respond to this acknowledgement by telling me what *his* drift was. You do so to defend your previous post because what I'm saying is true.

 

No, as a matter of fact I defend my previous post because what you're saying is wrong.

 

I also find it discouraging that you seem to rip on his ideas, instead of offering more constructive advice and direction, so that he might come to better understand the topic.

 

Perhaps you should look back in this thread and look for my earlier replies? And for other people's replies? It's not like we are not trying to help Harry - but his overall posting habit is not very productive.

[Harry Costas]

Hello Ewright

 

Thank you

 

Smile,,,,,,,,,,,,I have had too many years to worry about Mr Rip

 

But! Tormod is right. I have to be better at this.

 

I do have the knowledge and I do know that the more I know the less I know.

[Qfwfq]

From an early 20th century dictionary:

Plas"ma, n. [see {Plasm}.]

1. (Min.) A variety of quartz, of a color between grass green and leek green, which is found associated with common chalcedony. It was much esteemed by the ancients for making engraved ornaments.

 

2. (Biol.) The viscous material of an animal or vegetable cell, out of which the various tissues are formed by a process of differentiation; protoplasm.

 

3. Unorganized material; elementary matter.

 

4. (Med.) A mixture of starch and glycerin, used as a substitute for ointments. --U. S. Disp.

 

{Blood plasma} (Physiol.), the colorless fluid of the blood, in which the red and white blood corpuscles are suspended.

 

{Muscle plasma} (Physiol.), the fundamental part of muscle fibers, a thick, viscid, albuminous fluid contained within the sarcolemma, which on the death of the muscle coagulates to a semisolid mass.

No. 3 was clearly the basis for using the term to indicate a more or less complete separation between electrons and nuclei. Strictly, an ionized gas isn't necessarily a plasma.

 

It is also the basis for using the same term to indicate quark-gluon plasma.

 

There's not much point in saying what scientists "think" plasma is and whether they might be wrong, it's purely a matter of people agreeing which word to use for which thing. You can't "prove" or "disprove" a definition.

[ldsoftwaresteve]

Qfwfq:

There's not much point in saying what scientists "think" plasma is and whether they might be wrong, it's purely a matter of people agreeing which word to use for which thing. You can't "prove" or "disprove" a definition.

thanks.

[Harry Costas]

Hello All

 

One may need to study the phases of matter.

 

So that you will get to know the varies phases.

 

It is common for most to think that plasma is just ion-gas plasma.

 

 

Solid: A solid holds a rigid shape without a container.

Amorphous solid: A solid in which there is no long-range order of the positions of the atoms.

Amorphous glassy solid

Amorphous rubbery solid

Crystalline solid: A solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern.

Liquid: A mostly non-compressible fluid. Able to conform to the shape of its container but retaining a (nearly) constant volume independent of pressure.

Gas: A compressible fluid. Not only will a gas conform to the shape of its container but it will expand to fill the container.

Plasma: A gas in which electrons can become free of their atoms resulting in a distribution of charges able to conduct electricity.

Superfluid: A phase achieved by a few cryogenic liquids at extreme temperature where they become able to flow without friction. A superfluid can flow up the side of an open container and down the outside. Placing a superfluid in a spinning container will result in quantized vortices.

Supersolid: similar to a superfluid, a supersolid is able to move without friction but retains a rigid shape.

Degenerate matter: found in the crust of white dwarf stars. Electrons remain bound to atoms but are able to transfer to adjacent atoms.

Neutronium: found in neutron stars. Vast gravitational pressure compresses atoms so hard the electrons are forced into the nucleus, resulting in a superdense conglomeration of neutrons. (Normally neutrons decay with a half life of about 10.4 minutes, but in a neutron star, as in the nucleus of an atom, other effects stabilize the neutrons.)

Strongly symmetric matter: for up to 10-36 seconds after the Big Bang the energy density of the universe was so high that the four forces of nature, strong, weak, electromagnetic, and gravitational, were unified into one single force. Then the universe expanded, the temperature and density dropped, and the strong force separated, a process called symmetry breaking.

Weakly symmetric matter: for up to 10-12 seconds after the Big Bang the strong, weak and electromagnetic forces were unified.

Bose-Einstein condensate: a phase in which a large number of bosons all inhabit the same quantum state, in effect becoming one single wave/particle.

Fermionic condensate: Similar to the Bose-Einstein condensate but composed of fermions. The Pauli exclusion principle prevents fermions from entering the same quantum state, but by pairing up two fermions can behave as a boson and the pairs can then enter the same quantum state without restrictions.

Quark-gluon plasma: A phase in which quarks become free and able to move independently (rather than being perpetually bound into particles) in a sea of gluons (subatomic particles that transmit the strong force that binds quarks together). May be briefly attainable in particle accelerators.

Strange matter: (aka Quark matter) which may exist inside some particularly large neutron stars.

 

http://en.wikipedia.org/w/index.php?title=Phase_of_matter&redirect=no

http://en.wikipedia.org/wiki/List_of_phases_of_matter

[ldsoftwaresteve]

Costas:

Strongly symmetric matter: for up to 10-36 seconds after the Big Bang the energy density of the universe was so high that the four forces of nature, strong, weak, electromagnetic, and gravitational, were unified into one single force. Then the universe expanded, the temperature and density dropped, and the strong force separated, a process called symmetry breaking.

Weakly symmetric matter: for up to 10-12 seconds after the Big Bang the strong, weak and electromagnetic forces were unified.

I happen to think the Big Bang didn't, that Dark Matter doesn't exist and that most of our assumptions about the nature of matter are wrong.

So, I have a hard time accepting definitions that cause me to accept assumptions that I don't agree with. That's the good thing about definitions. Thanks, Harry, for putting them out in front of us.

[Harry Costas]

Hello ldsoftwaresteve

 

I like what you said.

And you are right.

 

The Big Bang in my opinion did not happen.

Its a pain that many cosmoligists and books are hooked on the BBT being the standard model.

But! there are many who are not.

 

As for Dark Matter thats another issue.

 

Most of the dark matter is in Black holes as so to speak.

 

I can talk more on this, but my time is limited.

 

Be back later

[Eclogite]

Most of the dark matter is in Black holes as so to speak.

No it isn't.

Why do you persist in making such inaccurate statements.

 

Yours affectionately,

Adolf.

[Tim_Lou]

should we get back to the topic of "how gravity affects space/time" ?

 

i am no expert in this field, however i found something really helpful in The Elegant Universe by Brian Greene

 

first of all, SR says that a moving clock runs slower than "usual" and a moving ruler seems to be shorter than "usual".

 

imagine a person going in circle near the speed of light, he measures the circumference of the circle. According to SR, his measurement will be smaller than if he had measured it at the center of the circle (stationary relative to the center). However, the measurement of the radius would not be different in both frame of references (relative to the center, and relative to the person moving).

 

space-time must be curved then, since the ratio isn't pi anymore.

 

according to the equivalent principle, gravitational field and acceleration is equivalent, hence gravity must also result in a curvature of space-time.

 

so that when a person sees an object at a different location, under the influence of a different gravitional field, the appearance of that object will be different and if the object is a clock, it's operational speed will be different.

 

 

well, its just my 2 cents... actually, Brian Greene's 2 cents.

[ldsoftwaresteve]

Tim_Lou:

so that when a person sees an object at a different location, under the influence of a different gravitional field, the appearance of that object will be different and if the object is a clock, it's operational speed will be different.

Tim, you are assuming that a gravitational field exists. If it doesn't, then what?