Black Holes

shane.mcneil · #1 19-01-2010, 05:59 PM

Hi, I've been reading about Black Holes and I notice that some people say that they destroy matter. But is that literally true? What happens to the matter that falls into a Black Hole? I would have thought that it must continue to exist in some form. Isn't it the matter in a Black Hole that makes the "gravity" of a Black Hole?

Regards, Shane

KenGee (Kenith Gee) · #2 20-01-2010, 01:12 AM

Basically we haven't got the tools to describe what happens inside a blackhole. It is said that matter is destroyed in blackholes because for all intents it has, as once it goes in it can not comeout.

mswhin63 (Malcolm) · #3 20-01-2010, 02:19 AM

I think in most, Black Holes are still theoretical and usually a bone of contention with science. I have heard that mass is reduced to an infinite level. Sounds like a load of codswallop. That would essentially mean there is no mass.

kustard (Simon) · #4 20-01-2010, 08:09 AM

I'm a bit rusty (ok, a lot rusty) but I think when they say that matter is destroyed it is to say that the material is broken down into sub atomic particles and compressed into a mathematical singularity.

They also postulate that at the edge of the event horizon matter can actually be created but I cannot remember the exact details. I really need to read my astro/science books again.

Jarvamundo (Alex) · #5 20-01-2010, 12:06 PM

I'm with Malcom... still theoretical objects...tho great fun to read about...

They can be used/invented to explain the energy needed to power up a quasar that we can see 2B to 10B light years away... (assuming that one believes redshift = velocity)..... i'm leaning to codswallop on that one too

enjoy the readings and the rabbit holes... There are some other cool theories and models of black holes including gravitational shielding of matter... lots of theories out there.

IIS should really have a book section... Does it? maybe i haven't found it yet.

shane.mcneil · #6 20-01-2010, 06:21 PM

Hmm all very interesting. It just seems to me that for a black hole to maintain a gravitational influence then the matter/energy that makes it up must still exist somehow. Otherwise there would no longer be a black hole?

Alex, just wondering what makes you wonder about redshift not equaling velocity. I know there are different types of redshift but I thought that it was fairly well understood?

Regards,

Shane

sjastro · #7 20-01-2010, 11:49 PM

Quote:

Originally Posted by shane.mcneil

Hmm all very interesting. It just seems to me that for a black hole to maintain a gravitational influence then the matter/energy that makes it up must still exist somehow. Otherwise there would no longer be a black hole?

Correct.

If there is one property about BHs that is well understood is it's mass. (Along with electric charge and angular momentum for spinning black holes).
The mass of a BH is calculated through Keplar's laws through objects in orbit around it.
The mass of BH varies from 1.4-3 solar masses for stellar type BHs up to 18 billion solar masses for BHs that reside at the centre of galaxies.

Due to the conservation of mass and energy, when matter falls into a BH it isn't destroyed. We may not know what form the matter takes except it becomes part of the BH mass.

Rather than being theoretical curiosities, the indirect experimental evidence for BHs is quite strong, particularly for supermassive BHs.

Regards

Steven

Jarvamundo (Alex) · #8 21-01-2010, 11:22 AM

Shane in response... ofcourse the standard doppler shift / velocity shift forms a component of local redshift... and well understood by honking a car horn as you drive by.... my interest or "wonder" is more at the extra galactic scales... particularly relating to hubble's expanding universe and all the objects that don't fit on a tidy hubble diagram.

Particularly interesting is the observed quantization of redshifts... which in the popular expanding homogeneous universe, simply isnt going to happen....

I've really enjoyed reading the papers and works by: G & M Burbidge, J Narlikar, H Arp on Quasars and their observations.... and Tom Van Flandern (i think is his name) has a cool book on push gravity and gravity shielding, relating to black holes... Also Eric Lerner's work on Plasma cosmology is interesting too... although i think he's moved more into power generation these days.

Some really interesting books from some of these guys include:
Halton Arp "Seeing Red - Redshifts, Cosmology and Academic Science"
This ones jam packed of observations on quasars and quantized redshifts (particularly of the two local galaxy clusters virgo.. and our viewable fornax)... whether you accept the theory or not, a cool feature of this book is to see and understand the graphs and charts that the pros use in papers...

Tom Van Flanderns - Dark Matter, Missing Planets (or something like that)... i like his psuh-gravity theory in this book.... and gravitational shielding leading to black holes... the mars stuff is pushing it a bit for me... but hey fun to read...

Eric Lerner - The Big Bang Never Happened (or something like that)... really cool stuff on the effects of plasma and EMF on our universe and on large scale structures...

It's my feeling that Black Holes, Dark Matter, Dark Energy at the moment are just comfortable mathematical solutions for some serious head scratching.... with the goal posts moving continuously...

Alot of big scopes are due to turn on soon... it's only just heating up i recon... woo hoo

All the best

Nesti (Mark) · #9 21-01-2010, 05:26 PM

Quote:

Originally Posted by sjastro

Correct.

Due to the conservation of mass and energy, when matter falls into a BH it isn't destroyed. We may not know what form the matter takes except it becomes part of the BH mass.

Regards

Steven

If the Black Hole's mass can be predicted, then the gravitational field can also be known. If the Field is known, then the Tidal Forces should be able to be approximated.

For any given Black Hole, I'm sure that there would be an estimate of whether its Tidal Forces were sufficiently strong enough to overcome the Weak Nuclear Force, perhaps even the Strong Nuclear Force. Also, whether the rapid convergence of matter, and subsequent collisions attributed to the convergence, could/would trigger a nuclear fission/fusion processes?

Is there perhaps several different type of radii; one which triggers fusion events, one which triggers fission, and ultimately one in which the Tidal Forces overcomes the different atomic forces...couldn't Black Holes have different types of event layers?

sjastro · #10 22-01-2010, 04:41 AM

Quote:

Originally Posted by Nesti

If the Black Hole's mass can be predicted, then the gravitational field can also be known. If the Field is known, then the Tidal Forces should be able to be approximated.

For any given Black Hole, I'm sure that there would be an estimate of whether its Tidal Forces were sufficiently strong enough to overcome the Weak Nuclear Force, perhaps even the Strong Nuclear Force. Also, whether the rapid convergence of matter, and subsequent collisions attributed to the convergence, could/would trigger a nuclear fission/fusion processes?

Is there perhaps several different type of radii; one which triggers fusion events, one which triggers fission, and ultimately one in which the Tidal Forces overcomes the different atomic forces...couldn't Black Holes have different types of event layers?

We can only consider the case of what happens ouside the horizon. Tidal forces become infinitely large at the singularity, but anything that occurs inside the horizon is pure speculation and cannot be observed.

At and near the event horizon, the tidal force on an object is a function of the radial length of the object and the mass of the BH. The smaller the length, the smaller the tidal force. This is because part of the object closer to the BH singularity will be subjected to a stronger gravitation force compared to part of the object furthest away. The tidal force is the difference between the forces. The smaller the mass of the BH the larger the tidal force. This is due to the event horizon being closer to the singularity.

When refering to strong and weak forces, objects can be no larger than atomic nuclei in which case the tidal forces are so small they will not be able to overcome the weak and strong forces, irrespective of the mass of the BH.

Regards

Steven

shane.mcneil · #11 22-01-2010, 06:27 AM

Thanks for your comments everyone. May I ask another question to see if I have understood things? I read that the reason you cannot escape from a black hole is not because you can't go fast enough but because spacetime curves so much that the only direction you can go in is towards the black hole. Beyond the event horizon that is. Is that right?

Thanks

Shane

sjastro · #12 22-01-2010, 10:13 AM

Quote:

Originally Posted by shane.mcneil

Thanks for your comments everyone. May I ask another question to see if I have understood things? I read that the reason you cannot escape from a black hole is not because you can't go fast enough but because spacetime curves so much that the only direction you can go in is towards the black hole. Beyond the event horizon that is. Is that right?

Thanks

Shane

If an object inside the event horizon emitted an electromagnetic signal before it is (presumedly) destroyed by tidal forces, the signal will travel along a geodesic path. This is simply the shortest distance between 2 points. Space-time is so curved the geodesic path always curves back towards the BH and never breaks out of the event horizon.

Regards

Steven