Supermassive black hole spins super-fast

Imagine a sphere more than 2 million miles across - eight times the distance from Earth to the Moon - spinning so fast that its surface is traveling at nearly the speed of light. Such an object exists: the supermassive black hole at the center of the spiral galaxy NGC 1365.

Astronomers measured its jaw-dropping spin rate using new data from the Nuclear Spectroscopic Telescope Array, or NuSTAR, and the European Space Agency's XMM-Newton X-ray satellites.

"This is the first time anyone has accurately measured the spin of a supermassive black hole," said lead author Guido Risaliti of the Harvard-Smithsonian Center for Astrophysics (CfA) and INAF - Arcetri Observatory.

This research is being published in the Feb. 28 issue of the journal Nature, and featured in a NASA media teleconference on Feb. 27th.

A black hole's gravity is so strong that, as the black hole spins, it drags the surrounding space along. The edge of this spinning hole is called the event horizon. Any material crossing the event horizon is pulled into the black hole. Inspiraling matter collects into an accretion disk, where friction heats it and causes it to emit X-rays.

Risaliti and his colleagues measured X-rays from the center of NGC 1365 to determine where the inner edge of the accretion disk was located. This Innermost Stable Circular Orbit - the disk's point of no return - depends on the black hole's spin. Since a spinning black hole distorts space, the disk material can get closer to the black hole before being sucked in.

NuSTAR helps solve riddle of black hole spin — Scientists measure the spin rates of supermassive black holes by spreading the X-ray light into different colors. The light comes from accretion disks that swirl around black holes, as shown in both of the artist's concepts. They use X-ray space telescopes to study these colors, and, in particular, look for a "fingerprint" of iron -- the peak shown in both graphs, or spectra -- to see how sharp it is. The "rotation" model shown at top held that the iron feature was being spread out by distorting effects caused by the immense gravity of the black hole. If this model were correct, then the amount of distortion seen in the iron feature should reveal the spin rate of the black hole. The alternate model held that obscuring clouds lying near the black hole were making the iron line appear artificially distorted. If this model were correct, the data could not be used to measure black hole spin. NuSTAR helped to solve the case, ruling out the alternate "obscuring cloud" model. Credit: NASA/JPL-Caltech.

Astronomers want to know the black hole's spin for several reasons. The first is physical - only two numbers define a black hole: mass and spin. By learning those two numbers, you learn everything there is to know about the black hole.

Most importantly, the black hole's spin gives clues to its past and by extension the evolution of its host galaxy.

"The black hole's spin is a memory, a record, of the past history of the galaxy as a whole," explained Risaliti.

Although the black hole in NGC 1365 is currently as massive as several million Suns, it wasn't born that big. It grew over billions of years by accreting stars and gas, and by merging with other black holes.

Spin results from a transfer of angular momentum, like playing on a children's swing. If you kick at random times while you swing, you'll never get very high. But if you kick at the beginning of each downswing, you go higher and higher as you add angular momentum.

Similarly, if the black hole grew randomly by pulling in matter from all directions, its spin would be low. Since its spin is so close to the maximum possible, the black hole in NGC 1365 must have grown through "ordered accretion" rather than multiple random events.

Studying a supermassive black hole also allows theorists to test Einstein's general theory of relativity in extreme conditions. Relativity describes how gravity affects the structure of space-time, and nowhere is space-time more distorted than in the immediate vicinity of a black hole.

The team also has additional observations of NGC 1365 that they will study to determine how conditions other than black hole spin change over time. Those data are currently being analyzed. At the same time, other teams are observing several other supermassive black holes with NuSTAR and XMM-Newton.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Explore further: The Milky Way's supermassive black hole

More information: dx.doi.org/10.1038/nature11938

antialias_physorg

3.2 / 5 (11) Feb 27, 2013

only two numbers define a black hole: mass and spin

Not quite. Three numbers define a black hole: Mass, angular momentum and charge.

Since its spin is so close to the maximum possible,

Z99

1 / 5 (6) Feb 27, 2013

I wonder why velocity, location, and age are not considered properties of a BH? Oh, and it is "electrical charge", fwiw.
Is spin more intrinsic than velocity? Aren't both relative to frame of reference? Spin is a vector, right? So, is that "a number"? How is spin vector defined in GR, 3-vector or 4?

dschlink

5 / 5 (3) Feb 27, 2013

Velocity is a vector and has no bearing on the nature of the black hole itself. The hole could be standing still or moving at thousands of kilometers a sec, but it wouldn't be changed. Ditto, location. There is no way to tell the age of a black hole. The accretion disk can carry clues, but a day-old hole and a billion year old look exactly the same.

ValeriaT

1.8 / 5 (10) Feb 27, 2013

Is spin rate of black hole defined in general relativity? If yes, how? Gravitational singularity has no diameter and the event horizon around it has no surface roughness, which would allow to observe it.

space music

1.7 / 5 (10) Feb 27, 2013

it's troublesome to be told that black holes, dark matter, and dark energy are a mystery, but yet they are accepted as empiricle.
and the standard model includes a boson called a graviton? is it hiding like the higgs? why would einstein say a warping of spacetime creates gravity....no graviton?.....wtf?

Shinichi D_

1.7 / 5 (6) Feb 27, 2013

I have a bit of a problem understanding this part. Since the event horizon isn't a physical presence (just an imaginary surface of no return) why is it (or rather the spatial dragging effect) bound to a spin slower than the speed of light?

It would no more be a black hole, if any part of it could rotate facter than c. A BH spinning so fast, is shaped like a '8'. The event horizon must have a dent around the equator.

The charge can not originate from the black hole itself. No mediator of electromagnetic forces (or any fundamental force) can get out. That's the definition of the thing. The charge is a result of frame draging i think.

EyeNStein

1.4 / 5 (9) Feb 27, 2013

A rotating black hole isn't a singular point object. It becomes a finite rotating disk ( albiet a small one). The spacial drag is understood to be related to gravity as magnetism is related to moving electric charges - a relitivistic effect.

3 / 5 (6) Feb 27, 2013

It would no more be a black hole, if any part of it could rotate facter than c

That's sort of the point. The event horizon isn't a physical part of the BH (just like the surfaces of constant potential between charged plates aren't physical parts of a capacitor - although in that case the force carriers are photons and changes in this surface WOULD be bound by the speed of light.)

But the article above is worded a bit murky. It seems to me they're talking about the speed of the framedragging effect. And the speed of a dragged frame isn't limited by c, is it?
(At least the speed of gravity hasn't yet been verified to be limited by c to my knowledge. The LIGO experiment is still ongoing)

2.2 / 5 (11) Feb 27, 2013

A rotating black hole isn't a singular point object. It becomes a finite rotating disk ( albiet a small one)

Black hole is a concept of general relativity and it does recognize only singularity and event horizon, nothing else. Everything else is just a subject of some hypothetical theory, which had not been developed yet.

Infinum

1 / 5 (8) Feb 27, 2013

When you are able to condense matter so that all its various quantum states (including all symmetries like for example CPT) collapse into 1 you get a black hole. Simply said, black hole is a region of space which is occupied by energy in only 1 single (super?) quantum state.

So when rotating there is no friction, a bit like with liquid helium flowing in a loop or with superconductors when they push out the magnetic field.

This also describes on the quantum scale why the light can not "escape" from a black hole. Both the electromagnetic spectrum and space-time are simply pushed out of black hole so there is no light inside black hole to escape and the space-time seems warped around such object.

Now if only I knew how to put it into equations :P
Any takers? Drop me an email n074v41l4bl34u[remove_this]@gmail.com :D

Modernmystic

1.9 / 5 (9) Feb 27, 2013

only two numbers define a black hole: mass and spin

Not quite. Three numbers define a black hole: Mass, angular momentum and charge.

Since its spin is so close to the maximum possible,

I have a bit of a problem understanding this part. Since the event horizon isn't a physical presence (just an imaginary surface of no return) why is it (or rather the spatial dragging effect) bound to a spin slower than the speed of light?

As I understand the phenomena frame dragging is "simply" space moving. Since it's space I don't think there is a "speed limit" per se.

http://en.wikiped..._effects

Sean_W

If a black hole is spinning at near the speed of light and you could move two other black holes near the poles of the first one, pulling it thinner, it should be like a figure skater spinning and drawing her arms in. Would this result in a razor sharp equatorial disk rotating within a hair of light speed and a slack teepee shape rising at each pole?

I hadn't planned on trying this experiment btw.

Zep Tepi

1 / 5 (7) Feb 27, 2013

So a black hole rips matter apart.

Seems to me it would have no mass. But mass rushes towards it to fill that void but it does mimick a very massive thing seeing as how matter rushes to it.

IMO.

gwrede

1.4 / 5 (10) Feb 27, 2013

Imagine a sphere more than 2 million miles across ... spinning so fast that its surface is traveling at nearly the speed of light

I presume the author is referring to speed at the equator.

This horrible rate of spin would be roughly two revolutions per MINUTE.

Now, let's make a little thought experiment. Say there is a lighthouse floating in space. Its light is so powerful that you can spot it at a million miles. (Which is the same as the black hole's radius.) Say the light rotates at the same two revolutions per minute. Now, what is the speed of the light cone at this distance of 1 million miles?

Answer: the speed of light. Now make the light stronger so the radius is doubled. What is the cone speed then? Answer: twice the speed of light.

So, I think either Prof. Risaliti, or the Caltech staff editor should do some more thinking.

(Incidentally, in my latter ex. the observer at 2Mm would see the light go quite normally! He wouldn't know anything is "wrong".)

Tuxford

1.8 / 5 (9) Feb 28, 2013

Some spin, some not...

http://phys.org/n...ole.html

"they find that the Milky Way's central black hole spin is at best modest"

Let's not get too excited.

Parsec

5 / 5 (1) Feb 28, 2013

Reading this article, I was reminded again about the principle of that in physics there really isn't such a thing as free lunch.

So I am curious how much energy is being radiated away from the black hole because of frame dragging. Obviously these space time distortions cost energy (right?), which has to come from the black hole itself.

Does this energy have a tendency to slow the spin rate, or does it come from the mass? If frame dragging does have a tendency to slow the spin over time, the effect must be quite small, or there has to be a countervailing force that is constantly increasing the spin rate.

Anyone out there with more knowledge that I have any idea?

1.4 / 5 (9) Feb 28, 2013

So far I have already got two Ones to my comment above. Seems this is is way too abstract for those who can neither think nor have a calculator.

Fleetfoot

5 / 5 (5) Feb 28, 2013

So I am curious how much energy is being radiated away from the black hole because of frame dragging. Obviously these space time distortions cost energy (right?), which has to come from the black hole itself.

A BH is spherically symmetric so doesn't radiate. Mergers and ripples in the surface due to infalling additions create transient asymmetry which radiates gravitational waves until the symmetry is restored. That's why just three values define everything, any distortions of shape decay away rapidly.

5 / 5 (4) Feb 28, 2013

Imagine a sphere more than 2 million miles across ... spinning so fast that its surface is traveling at nearly the speed of light
I presume the author is referring to speed at the equator.

This horrible rate of spin would be roughly two revolutions per MINUTE.

Now, let's make a little thought experiment. Say there is a lighthouse floating in space. Its light is so powerful that you can spot it at a million miles. (Which is the same as the black hole's radius.) Say the light rotates at the same two revolutions per minute. Now, what is the speed of the light cone at this distance of 1 million miles?

The path of a photon in that beam would be a null geodesic as always hence the speed measured relative to every observer it passes on that path is exactly the speed of light in vacuum.

rah

1 / 5 (6) Feb 28, 2013

I don't believe that speed for something so big. I expect to see a correction or retraction of this article. It just seems too ridiculous.

Three numbers define a black hole: Mass, angular momentum and charge.

As I understand the phenomena frame dragging is "simply" space moving. Since it's space I don't think there is a "speed limit" per se.

Correct, speed depends on the coordinate system and distance from the BH, the term has been simplified for the press, GR actually places a limit on the angular momentum as has been said previously.

ChangBroot

1.3 / 5 (13) Feb 28, 2013

Wow!!! Everyone Talks about this article as if our knowledge is 100% right about those tiny dots captured by some EXTRAORDINARY weak weak telescopes (any kind I mean). Why don't anyone question the process how they take a picture or analyze those pictures. I mean, literally, we should as questions about how those pictures are taken, analyzed and interpreted. We still can't take an HD photo of Mars with the most advanced telescope (i.e. Hubble etc), yet these so called scientists give us extreme details about things that are so far that the distance between Earth and Mars becomes insignificant. I am sorry, but I just don't buy these articles as true. These articles are for the naive.

So I am curious how much energy is being radiated away from the black hole because of frame dragging. Obviously these space time distortions cost energy (right?), which has to come from the black hole itself.

So your saying that frame dragging doesn't require any energy? I find that surprising, but at the same time I know that the slowing of time because of the gravitational field doesn't take any energy so I guess I can buy that.
A BH is spherically symmetric so doesn't radiate. Mergers and ripples in the surface due to infalling additions create transient asymmetry which radiates gravitational waves until the symmetry is restored. That's why just three values define everything, any distortions of shape decay away rapidly.

Sanescience

1 / 5 (5) Feb 28, 2013

Conversations I've seen about black hole theories:

The geometry of black holes might be a continuum from spheres to toroids depending on spin rate. The geometry also can be affected by proximity to other gravity wells like companion stars or other black holes.

The center region (outside of the event horizon) of the toroid is a kind of crucible which forms the jets that emanate from the "pols" and might be what looks like a quasar when pointed at earth.

Black holes are only understood in terms of relativity. Quantum mechanics might not actually allow the creation of "singularities", but rather space-time-matter-energy might exist in a phase form not yet described.

TBH: http://arxiv.org/.../0004051

And regarding age of a BH, the singularity might grow to meet the event horizon:

http://www.scient...p;page=1

Far out stuff!

2 / 5 (5) Feb 28, 2013

That's sort of the point. The event horizon isn't a physical part of the BH ..
But the article above is worded a bit murky. It seems to me they're talking about the speed of the framedragging effect. And the speed of a dragged frame isn't limited by c, is it?

Yes, but the event horizon is the only part of the BH that is connected to our space-time. It's a boundary, where the escape velocity is always c. If the event horizon rotates, the escape velocity would be lower at the equtor. But that can not happen. It would go against tha upper definition. So a rotating BH's event horizon behaves counterintuitive. The faster it rotates, the more dented it becomes around the equator. A rotating BH is not flatened, like a rotating neutron star, it must be elongated towards the poles.
The frame can be dragged faster than c(?). But that has nothing to do with where the boundary (event horizon) is. It's always where the photons move paralel to each other, never falling in never escaping.

Ducklet

1.1 / 5 (7) Feb 28, 2013

Are we talking "spin" as in QM, or "angular momentum" as in CM? I.e., is it the particle-like singularity's spin property we're talking about, or an as of yet unproved theory about the mass in the BH having some kind of definable surface and diameter? Because clearly something infinitely small can have no angular momentum and like others have pointed out the EH is a derived property, not an object, so can't rotate independently of the object it's a property of.

The EH also isn't a perfect sphere and appears to repel from mass. A VERY dense accretion disk would indent the EH at the disk plane and extend it at the poles.

5 / 5 (2) Feb 28, 2013

So your saying that frame dragging doesn't require any energy? I find that surprising, but at the same time I know that the slowing of time because of the gravitational field doesn't take any energy so I guess I can buy that.

Well you can think of gravity round the Earth as being a curvature generated by the energy (mass) of the planet but once formed, it takes no more energy to maintain it. The same applies to the black hole, you have to feed it angular momentum to create the curved frames which we see as drag but once it is spinning, the effect is always there.

If an object moves closer and is accelerated, conservation of angular momentum means the BH will be slowed slightly but of course it regains what it lost when the object falls in.

5 / 5 (3) Feb 28, 2013

Wow!!! Everyone Talks about this article as if our knowledge is 100% right about those tiny dots captured by some EXTRAORDINARY weak weak telescopes (any kind I mean). Why don't anyone question the process how they take a picture or analyze those pictures...

Because those problems are explained in the detailed papers and science has a rule that anything published has to be "peer reviewed" first. It has to be checked critically by people not involved in the study who are sufficiently qualified to identify any problems in the analysis.

The other point is that this is not an unusual result for smaller stellar black holes.

Urgelt

3 / 5 (4) Feb 28, 2013

To those who insist that 'charge' is a separate and discreet number that can be assigned to a black hole: if this is true, then there must be a mechanism by which a surplus of positively or negatively charged particles are included in the mass of the black hole (not that they are now particles, as such, in that extreme environment), and oppositely charged particles, in some unbalanced amount, are ejected as radiation. One would think that we might devise methods of observation to confirm this.

Which brings me to a second point: if you tear assunder an electron or proton to be incorporated into the mass of a black hole, does the charge of that former particle somehow linger on without the particle itself? I'm not sure I've heard a theoretical answer to that question (and an empirical answer might be rather difficult to obtain!).

.. there must be a mechanism by which a surplus of positively or negatively charged particles are included in the mass of the black hole (not that they are now particles, as such, in that extreme environment), and oppositely charged particles, in some unbalanced amount, are ejected as radiation. One would think that we might devise methods of observation to confirm this.

It is theoretically possible, however a positively charged BH would tend to repel incoming protons and attract electrons from the accretion disc so it is likely that they will be close to neutral in practice hence very difficult to observe.

Which brings me to a second point: if you tear assunder an electron or proton to be incorporated into the mass of a black hole, does the charge of that former particle somehow linger on without the particle itself?

The particles will merge with whatever form exists at the centre, current theory cannot say, but charge is conserved so will add to that of the BH.

The 'observables' - frame dragging and the waves have not been detected. There are two camps. They will be detected. They will not be detected.

There is a third camp that thinks frame dragging was confirmed in 2004 and gravitational radiation (indirectly) in 1978:

http://www.univer...nfirmed/

http://www.nasa.g...rag.html

http://www.nobelp...ess.html

Moebius

1 / 5 (5) Mar 01, 2013

Any bets that, assuming it's possible, it's proven that singularities do not exist at the center of black holes and the mass has a finite volume? Infinities don't exist, either big or small or it was the unalterable future that I posted this.

4.7 / 5 (3) Mar 01, 2013

Any bets that, assuming it's possible, it's proven that singularities do not exist at the center of black holes and the mass has a finite volume?

I suspect that's what most scientists expect, the question is what is the nature of the energy in that state.

Infinities don't exist, either big or small ..

Infinite temperature exists but absolute zero doesn't. It's just a question of definition, if we had defined the measurable as 1/T then it could go through zero but would always be finite.

.. or it was the unalterable future that I posted this.

I don't see the connection.

1 / 5 (6) Mar 01, 2013

In general relativity the black hole is formed with space-time only and the space-time cannot rotate just in general relativity. Of course, the quantum mechanics will beat whole the black hole concept on its head and it will make it comparable to very dense star with fuzzy physical surface roughly equivalent to the surface of event horizon predicted with general relativity (actually the neutrino and graviton/axion star). Such an object can already rotate and drag its neighborhood like the whirlpool.

5 / 5 (2) Mar 02, 2013

In general relativity the black hole is formed with space-time only and the space-time cannot rotate just in general relativity.

Rubbish, a rotating black hole is described by the Kerr Metric solution to GR:

http://en.wikiped...cal_form

Don't spread disinformation if you can't even be bothered to check Wikipedia, never mind actually learning the subject.

Of course, the quantum mechanics will beat whole the black hole concept on its head and it will make it comparable to very dense star with fuzzy physical surface roughly equivalent to the surface of event horizon ..

Almost, it will be a very dense fuzzy object but with a size smaller than a neutron, probably around the deBroglie wavelength of the components since the degeneracy pressure produced by the Pauli Exclusion principle has already been overcome.

3.4 / 5 (5) Mar 02, 2013

So a rotating BH's event horizon behaves counterintuitive. The faster it rotates, the more dented it becomes around the equator. A rotating BH is not flatened, like a rotating neutron star,

Well the event horizon isn't flattened, but you get the ergosphere (the area where framedragging happens) which is flattened:
http://en.wikiped...gosphere

When I read the wikipedia link I come accros:

Within the ergosphere, spacetime is dragged along in the direction of the rotation of the black hole at a speed greater than the local speed of light in relation to the rest of the universe.

Which seems to contradict what the article claims:

New measurements show that the black hole at the center of galaxy NGC 1365 is spinning at close to the maximum possible rate.

and

spinning so fast that its surface is traveling at nearly the speed of light.

Anyone know what I am missing?

3.7 / 5 (3) Mar 02, 2013

When I read the wikipedia link I come across:
Within the ergosphere, spacetime is dragged along in the direction of the rotation of the black hole at a speed greater than the local speed of light in relation to the rest of the universe.

Which seems to contradict what the article claims:
New measurements show that the black hole at the center of galaxy NGC 1365 is spinning at close to the maximum possible rate.

and
spinning so fast that its surface is traveling at nearly the speed of light.

Anyone know what I am missing?

It's not your problem the article is badly written. The actual finding is that the BH has nearly the maximum angular momentum which affects the radius of the internal horizons. The location where the tangential speed is the speed of light is the definition of the outer boundary of the ergosphere so that "surface" moves at the speed of light by definition.

This gives a lot more detail!

http://www.eftayl...nNEW.pdf

Mr_Man

1 / 5 (1) Mar 02, 2013

Interesting idea, but I wonder how the jets of energy/ particles that are jettisoned off the poles of the first black hole would effect the relationship of the other two? Also the other two would have to be almost the exact same distance away from the first and they would all have to have the same velocity and trajectory. Obviously your question was totally hypothetical and I still would like to know the answer as well.

Lurker2358

1 / 5 (5) Mar 02, 2013

Does this energy have a tendency to slow the spin rate, or does it come from the mass? If frame dragging does have a tendency to slow the spin over time, the effect must be quite small, or there has to be a countervailing force that is constantly increasing the spin rate.

Angular momentum is ultimately "Energy," in a different form, and at least according to Einstein and every experiment that is provable, "E=mc^2".

So since E=mc^2, then by extention, m=E/(c^2).

The voyager spacecraft proves this with the famous "sling-shot" maneuver, which robs Jupiter of a tiny amount of "angular momentum". This becomes "Kinetic Energy" (by definition of the term Kinetic Energy,) since it modifies the crafts "velocity". Although I personally believe that one or the other of "Momentum" and "kinetic Energy" must be a "fictitious force" that's another discussion.

However, with Black Holes there is another issue, since they supposedly warp space-time, so that all dimensions become "time-like".

1 / 5 (6) Mar 02, 2013

It is suggested by some black hole physicists (or at least science authors attempting to explain them,) that the dimensions of space itself "fall"into the black hole, so that not just the matter or energy, but "dimension" becomes trapped in the black hole. This led to the thought experiment of whether a black hole might be larger on the inside than on the outside. I think the first time I saw this proposed semi-formally was in a black hole related novel by Clifford Pickover, though it may have been explored previously by Stephen Hawking or by science fiction authors.

Pickover was writing "real" science theory, but was using a series science fiction short stories and examples to illustrate principles.

The point is the "axis" of dimension begins to fall into the black hole, not just the matter or energy those dimensions contain, and because of this, if you were inside the event horizon of a Bh and looked towards it's CoG, you would see another event horizon and another and another...

Whydening Gyre

1 / 5 (9) Mar 02, 2013

Which brings me to a second point: if you tear assunder an electron or proton to be incorporated into the mass of a black hole, does the charge of that former particle somehow linger on without the particle itself? I'm not sure I've heard a theoretical answer to that question (and an empirical answer might be rather difficult to obtain!).

Perhaps the LACK of it's charge lingers outside of the black hole.

5 / 5 (2) Mar 03, 2013

@Fleetfoot
Gravity B Probe project was terminated.
Why?

I believe the project was curtailed because the data had a higher level of random noise than was expected. Last I heard, the suspicion was that it was due to static charge buildup on the quartz sphere gyros but that was some years ago, they may have confirmed the cause since then.

The final results are here:

http://einstein.s...us1.html

There may be more on the problems you can trace from that site.

- Ff

Read more at: http://phys.org/n...html#jCp

What is the rate of bound in the limit as T approaches the infinite?

Your second link was to this article itself so I don't know if you wanted me to read something else.

Until someone works out a theory which combines GR and QM, nobody knows what happens at the Planck scale. Somewhere beyond the onset of the QGP, the process of baryogenesis will reverse and at some stupidly high density, gravitational waves may become comparable to other forms of energy so it all becomes speculative at present IMHO.

5 / 5 (4) Mar 03, 2013

Angular momentum is ultimately "Energy," in a different form, and at least according to Einstein and every experiment that is provable, "E=mc^2".

That is only valid for an object in its rest frame.

So since E=mc^2, then by extention, m=E/(c^2).

The full form is m^2 = E^2 - |p|^2
in units where c=1.

http://en.wikiped...relation

Although I personally believe that one or the other of "Momentum" and "kinetic Energy" must be a "fictitious force" that's another discussion.

Neither is a force but you are right, kinetic energy isn't something in isolation. The energy is the projection of the momentum-energy 4-vector onto the time axis and the "kinetic" part is just the amount by which that exceeds the rest energy. One definition of mass is that it is the magnitude of the 4-vector.

.. all dimensions become "time-like".

Only the radial direction switches to being time-like as the light cones lean by more than 45 degrees.

1.4 / 5 (10) Mar 03, 2013

It is the new way of looking at the oldest concept known to humankind - the concept of time.

And all this time I thought it was sex...

5 / 5 (1) Mar 03, 2013

...nobody knows what happens at the Planck scale... - Ff

Of course you do. And you know what happens beyond this too.

"Their results show that, no matter what the temperature or the particle, the rate at which they bounce off each other – 'scatter'– changes by the same amount as the temperature is changed."

Read more at: http://phys.org/n...html#jCp

"...by the same amount..." is a constant independent of T and density.

Sure, just as there is a plateau at the Haegdorn Temperature, but beyond that things change. We don't know how far that effect will last but they are many orders of magnitude short of the Planck scale and haven't even approached the GUT scale yet. Beyond that we know nothing.

melitta_vahalik

1 / 5 (6) Mar 03, 2013

It keeps you occupied while UN Agenda 21 is being implemented.

Requiem

1 / 5 (7) Mar 04, 2013

Shouldn't the area within the event horizon of a black hole be an ever-growing sphere, toroid or like the rings of Saturn due to infinite or near-infinite time dilation in that region?

Shouldn't time not pass at all within the black hole, much like photons, muons and other particles traversing the universe don't experience significant time until they begin to encounter the dense matter of our atmosphere and/or collectors?

I'd expect the inside of a black hole to have the nucleus of whatever initially collapsed at the center, surrounded by matter in whatever state it was in when it crossed the event horizon - suspended in that time, state and position forever(or nearly forever) relative to normal space. I imagine it would begin at the initial event horizon and as it fell in, it would increase the overall mass of the system and therefor push the event horizon and position of all future infalling matter out.

Relative to the nucleus, this area would have low density and massive radius?

Addendum to my previous post:

Like snow collecting on the ground. The ground being the initial event horizon, and the snow flakes being the inbound particles?

5 / 5 (1) Mar 04, 2013

We don't know how far that effect will last...

Well, that's what it is there for...to see how far it lasts.

Quark gluon plasma dispels the notion of Haegdorn Temperature.
You know this, however.

The Hagedorn Temperature marks the phase transition. Once it is complete, the temperature rises again.

Only two outcomes. It lasts. It does not last.

Exactly, it could be either, we do not know which, as I said.