Black hole info

[gameforanything1]

A bit of info for you guys.....<br /><br /> Hawking changed his mind after 30 years

 

[igorsboss]

I suppose recoloring them brown wouldn't be very polite...

 

[gameforanything1]

Lol. <br /><br />CNN Headlines - " Slightly off-black holes send information in first class post "

 

[spayss]

Hawking is a phenomenal individual who has much to offer. I look forward to his paper. But, he's not quite as revered is physics circles as much of the press would have us believe. There will be some sighing and eye-rolling in the theoretical physics community...'here we go again'..the press will lap it up and many researchers will go back to their equally valid theories. This isn't to knock Hawking but to put the fellow in perspective.

 

[tad10734]

I have a hypothesis about black holes, the speed of light and the velocity that gravity has on objects at the event horizon and beyond and what we see through a telescope.<br /><br />I hypothesize that the velocities that the gravitational forces of a black moves objects faster than the speed of light once they reach and proceed through the event horizon. <br /><br />An example: <br />Take a vacuum cleaner for instance. If the force of the vacuum equals the mass of the object being sucked in, the object would be stuck in the opening. So, if light or any other kind of matter, for that matter, is the object then light would be stuck at the opening hence making it a white hole. For light not to be able to escape, the force of the gravitational pull would have to create velocities greater than the speed of light.<br /><br /><br /><br />

 

[enigma10]

So a black hole has vacuum attachments? <br /><br /><i>I name that one Dyson, and that one Dirt Devil!</i> <div class="Discussion_UserSignature"> <em>"<font color="#333399">An organism at war with itself is a doomed organism." - Carl Sagan</font></em> </div>

 

[alokmohan]

Hawking is well known and outstanding physicist.We possibly have no right to make such comments.We should read Hawking in website.

 

[nrrusher]

<br />"the force of the gravitational pull would have to create velocities greater than the speed of light. "<br /><br />That is something I have not seen/thought of before....and I like it. Gravity is the key to the universe in my humble opinion.

 

[jaxtraw]

The orthodox view is that light in a black hole is forced to go round in circles at the event horizon, so it isn't "stalled" as such, so the gravity doesn't need to pull it faster than light.<br /><br />Personally though my own cranky view is that black holes don't exist. I think they're one of those things, like tachyons, which can be described by math but don't actually exist in the real universe. The reason the laws of physics seem to break down in a singularity is that singularities are IMHO impossible, since infinities don't really exist as physically realised.<br /><br />Ranting on, IMV, the Pauli Exclusion Principle seems to me from the math to be as absolute as, for instance, c being the universe's top speed. So when "too much matter" tries to collapse on itself (i.e. more than the Chandrasekhar limit) the matter is crushed out of existence and disappears in a puff of energy. Which might be what is powering quasars, rather than energy released in accretion disks (though that would be a part too).<br /><br />Imagine throwing a tonne of extra matter onto a neutron star. Will it collapse into a black hole? I think not. I think, with little justification TBH, that the collapse will <i>start</i> but the neutrons at the centre of the star will, obeying the PEP, refuse to enter the same quantum state and, having no other choice, disappear and be replaced by their equivalent energy, which warms the neutrons a bit and halts the collapse.<br /><br />Just MHO of course <img src="/images/icons/smile.gif" />

 

[alokmohan]

Black holes are not that black as Hawkins say.They radiate.

 

[dutchie]

...and knowing that this radiation is called "Hawking radiation" the circle has been closed again.. <img src="/images/icons/wink.gif" />

 

[dutchie]

<blockquote><font class="small">In reply to:</font><hr /><p>For light not to be able to escape, the force of the gravitational pull would have to create velocities greater than the speed of light. <p><hr /></p></p></blockquote><br />I don't see why the escape velocity of a black hole could not exceed c. Your sentence states that "the gravitational pull creates velocities". IMO, it creates nothing. It's just impossible for light particles to leave the hole, because they can't reach the escape velocity.

 

[CalliArcale]

You're correct; the escape velocity can (and no doubt does) exceed c. The event horizon, as I understand it (note: I am a software engineer, not a physicist), is the altitude at which it is exactly c, so anything lower should exceed it. But since nothing can actually travel faster than c, it's doomed at that point. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[jaxtraw]

It's not about escape velocities per se, that's a bit Newtonian. The event horizon is the point beyond which all possible futures (worldlines) of a particle point towards the singularity.

 

[jaxtraw]

"Black holes are not that black as Hawkins say.They radiate."<br /><br />Not sure why you posted this but it's not the black hole itself radiating, it's the space around it, to be technical.

 

[docm]

No, it's the black hole itself. In fact, they can evaporate if they don't 'feed' enough to compensate for their emission of Hawking radiation. <br /><br />The people at CERN are depending on this because they plan to make mini black holes, maybe even 'black Saturns', in the Large Hadron Collider once it begins operations. <div class="Discussion_UserSignature"> </div>

 

[jaxtraw]

Nope. One understanding of Hawking Radiation is that virtual particle/antiparticle pairs form in the area immediately surrounding the black hole. One of them falls into the black hole, the other one gets enough energy to escape, becoming the radiation. The one that falls in has negative energy and thus decreases the mass of the black hole.<br /><br />The radiation isn't coming from the hole. It's coming from the highly deformed space around it.

 

[docm]

And if that negative energy inflow exceeds the 'feeding' rate the hole evaporates at a rate inverse to its mass, right? <div class="Discussion_UserSignature"> </div>

 

[derekmcd]

The radiation only seems apparent from a perspective outside the black hole. The radiation doesn't actually come from the black hole itself.<br /><br />I like to think of it as 'borrowed' energy. The particle/anti-particle pair borrow energy upon their creation. Normally, they would recombine and payback the energy. If one of the pair is given enough energy to separate from the other, it becomes a real particle to someone observing it. The energy in this particle was borrowed from space just outside the event horizon. The other particle that falls into the black hole has to compensate for the energy that was given to the now 'real' particle, thus keeping the conservation of energy intact. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[dutchie]

<blockquote><font class="small">In reply to:</font><hr /><p>The radiation isn't coming from the hole. It's coming from the highly deformed space around it.<p><hr /></p></p></blockquote><br />I can remember reading somewhere that matter surrounding the hole gets accelerated to enormous speeds before being drawn into the hole, causing this matter to heat up and start radiating x-ray energy. Of course I could be wrong...

 

[derekmcd]

You are correct, but plasma jets are completely unrelated to hawking radiation.<br /><br />Plasma jets are a by-product of an accretion disc. A rotating black hole swirls the infalling matter around the event horizon as such high speeds that the matter become highly energized and superheated (plasma). It is believed a magnetic field created by this superheated, fast swriling plasma launches these jets from the polar axis of the black hole.<br /><br /><br /> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[dutchie]

Thanks for your explanation. On this picture such a jet is visible. It is emanated from M87.<br />

 

[alokmohan]

Very correct.It radiates due to loss of spin energy.Only spinning black holes lose energy.

 

[dutchie]

Article on Suzaku measurements:<br /><b>The Edge of a Black Hole</b><br /><br />Black holes at the center of galaxies - so called active galactic nuclei (AGN)- are prime targets for Suzaku's instruments. <br />X-rays from AGNs have a strong spectral line emitted by iron atoms. In a laboratory, the energy of this line is fixed at 6.4 kilo electron-volts (keV for short). There also is a "continuum" of X-rays in the spectrum, containing X-rays of every conceivable energy from below 1 keV to above 100 keV. (Read more about continuum vs. lines in the spectroscopy primer) <br /><br />The energy of the iron line doesn't always stay at 6.4 keV, though. The motion of gas around a black hole causes Doppler shifts: when the line-emitting gas is coming towards you as it moves around in the accretion disk, the line is shifted to shorter wavelength (or higher energy) - it's blue shifted. It can also lead to red shifts, when the gas is moving away - this is a shift to lower energy.<br /><br />But there is more. The gravity of the black hole is so strong that it saps energy out of the X-ray photons as they climb out of the depth of the strong gravitational well of the black hole, causing the line to appear shifted to lower energies. This is called "gravitational red shift." The combination of Doppler shift and gravitational red shift causes the iron line to broaden over a range of energies, with a characteristic shape. (Read about and see an animation about this.) <br /><br />The exact shape of this broad iron line can tell us a lot about the nature of the black hole and the flow of superheated gas around it. Although scientists have known about the broad iron lines, Suzaku allows the most precise measurements of them to date. This is because the combination of the XIS and the HXD covers X-ray energies from below 1 keV to above 50 keV. So scientists can determine the shape of the spectru

 

[unseen]

could a black hole actually rip space time with it's gravity and create a new much obviously smaller universe. it would be that universe's big bang. no info would be lost and as the matter around the hole is all sucked in when there is no other matter to left around the black hole space time that was ripped actually forms back to where it was (heals itself so to speak)before the the black hole ripped it. this could go on and on until there is not enough mass to create black holes anymore....... <div class="Discussion_UserSignature"> </div>