Could a super energetic light pulse create a black hole?

For all we know this univserse is a kid's experiment that went wrong in an advanced science lab - worst still - he hasn't told his parents about it!



Yes the Universe could have largely ended and we wouldn't know about it - being nowhere important - for millions or billions of years even. Our part of the Universe mightn't have got the kill signal yet!

But doomsday aside, a rip in spacetime could do wierd things - bad or good - who knows!

Hi bill: Few of us, including me, can do the advanced math, so we are mostly collecting trivia on these physics subjects. Most lay persons are of the opinion that black holes gobble big time, but a few things have been said that indicate more moderate and less disaster. Perhaps wishful thinking on my part. If the almost light speed ten solar mass black hole passes though the center of our sun, the passage time is about 5 seconds, so our sun's orbit will be accelerated perhaps a million g for 5 seconds and more than one g for perhaps one minute before and after the collision. s= 1/2 at squared = 12 million feet = 2300 miles the sun is moved during the actual collision. My guess is a million years will elapse before we can measure the small change in the sun's orbit (around the galaxy) and the planet's orbits won't change much either. The accretion disk of the black hole will gain lots of mass while it is inside our sun, so the exit hole will be much larger than the entrance hole. My guess is a violent mass ejection will follow the black hole as it leaves the vicinity of the sun. If Earth is in the wrong place we might be toast, but otherwise the effects will be minor IMHO. In the accretion disk the matter is orbiting at almost the speed of light just outside the event horizon, so orbital collisions convert most of the matter to gamma photons which travel at the speed of light toward the event horizon. 1/4? of the gamma rays escape the accretion disk, as does perhaps 99% of the less energetic photons produced miles outside the event horizon. Perhaps 30% of the matter in the accreation disk escapes due to collisions. 50% of the accreation disk mass enters the event horizon over the next million? years. Evaporation of ten solar mass black holes and larger is almost irrelevant. Please embellish, refute or comment. Neil

I'm a total layman on this subject. To satisfy my inner nerd, I've read perhaps 50 hours worth of info on the subject and probably retained very little. Someone here sent me to a link that proved relativity, but I still can't get my head around the idea of space-time. Considering the delicate balance of more things than I can name, I would have to assume any "rip in space-time" that affected us even a little, would be catastrophic.

Neil: I don't imagine a black hole gobbles very often, but gobbles voraciously when it encounters other matter. I really wouldn't know where to start trying to figure out if a black hole traveling at near luminous speed would encounter more or less matter than one standing still... on average. But, with luck, it might encounter lots of stuff. And of course, the more it encounters, the more dense and dangerous it becomes.

I don't think you would have an accretion disk on a black hole traveling at .99 c either… perhaps an accretion trail? It seems most scientists still believe nothing can travel faster than light (I believe this will be proven false very soon), but in this model the matter on one side of an accretion disk would have to. I also think considering the speed its traveling, it would gobble what it was going to, and leave the rest behind, rather quickly... not a million years.

Lastly, I think a direct collision with our sun by an object with 10 times its mass would be catastrophic to life on earth. I can only assume that such a collision would cause shockwaves from impact that would cause sunbursts of radiation like we've never even imagined. Who knows, maybe she'd even go supernova?

(feel free to bash me for my ignorance all you wish. I love learning about this stuff and will take any and all criticism as constructive)

A one solar mass black hole more than a light year away might be impossible to confirm.We have not found any with that small a mass, but theory suggest they can have Earth mass or less, except we don't know a mechanism for producing low mass black holes.
One million miles from a one solar mass black hole should be exactly like one million miles from our sun as far as gravity is concerned. Our sun captures comparatively little matter and does not have an accretion disk of significance, so I suspect many small and mid size black holes exist for billions of years without gaining even 1% in mass. I think we could regard the rings of Saturn as an accretion disk.
Likely typical black holes are traveling less than 1% of light speed with respect to other matter a few light lears away, so .99 c is very speculative. There may be zero that fast within a billion light years of here. Neil

Case in point:

News May 2004: Discovery of a dipping probable black hole binary in NGC 55

A one solar mass black hole? The estimated minimum mass required to form a black hole in the first place is between 5 and 15 solar masses, if memory serves. Correct me if I'm wrong, but at one solar mass it could not compress beyond the density of a Neutron Star if, indeed, it even passed a tightly packed White Dwarf. Anyway, even if it were possible, it would be simple to detect at 1 million miles away if it encountered a smaller star. (That would be spectacular to see, wouldn't it?) BTW, do you have any links theorizing a black hole of earth mass or less? Sounds very improbable to me.

.99 c is pure speculation, only introduced because of g_day's post. The implications of a black hole traveling a 1% c would be every bit as potentially destructive. At the slower (which is still ridiculous fast, IMO) pace it would gather more matter from whatever it encountered.

Neil, that would have a Schwarzschild radius of about 30kms and it would just rip away anything that passed the event horizon. A 30km hole through the Sun would be a catastrophic event, the activity in terms of X-rays would fry the Solar System.

Great link Mr. Stillwater, thanks!

I've done some readings and only rest mass creates gravity so no, the light wont make a black hole because photons have 0 rest mass.

This was my understanding as well.

G-day,

I hope I am not getting too far off topic here but earlier in this thread there was a comment that led me to think that this question may well be related.

If light, when observed as light, is subject to gravity (or curved space-time) would it be unreasonable to conclude that light is also subject to the mechanical force called inertia?

If light has inertia then we must expect light to lag behind the accelerations provided by gravity.

Since gamma particles are so short lived in our "time" yet are able to traverse great distances could we perhaps conclude that they were accelerated at the source to the speed of light thus time did not pass for them?

This also would indicate that the "speed of time" which is related to mass always exceeds the speed of light.

Personally I relate this to potential errors in interpreting the "red shift" when used as evidence that the universe is expanding.

Am I completely "out to lunch" or is the difference between "c" and "time" accounted for in the theories that you have run across.

Thanks everybody. M.

You have made a wrong turning there about light. It is massless, which is why it travels at that speed.

Light is not deflected by gravity. What happens is that space is curved or distorted by gravity. Light passing by it still travels in a straight line - it is the the space that is 'deflected'. This phenonomon is known as 'lensing'.

Thanks Mr. Stillwater,

What bothers me mechanically is that space-time which can be construed as the distance between massive objects is warped by mass when light which can be construed as having an energy related mass is not affected by gravity.

Please don't spend a lot of time on this as it may be beyond me anyhow

But I still have one more little curiosity .

What part of relativity theory is used to justify the precession of the planet Mercury, or vice versa?

Light has relativistic mass (it has energy) which most physicists just refer to as energy nowadays because saying something that is massless has a mass is misleading. At least that's what I've gotten from reading up on this subject.

If you have 0 rest mass you will always travel at the speed of light. The speed of light is always 300 000kps approx relative to all observers.

Blah blah blah

Tobruk, Just for grins How do you resolve this

First you notice that this is a definition of a meter in our spacetime
This is what bothers me.

Near a black hole (should one exist) there will be a region of space relative to us that has an escape velocity of say 280,000 kps. Any energy emanating from that "hole" will have a forward (towards us) motion of 300,000kps minus 280,000 kps. or 2,000kps but when we "see" it it will have a forward motion of 300,000 kps but the same number of waves will emanate per second as we see. This is called a "gravitational red shift" but what wave length would our hypothetical hole generate when we see them?

Any notion

Well I have been following this up in the high energy section of an advanced physics forum - slow going, but at last signs of progress.

http://www.advancedphysics.org/viewthread.php?tid=698

and here

http://www.advancedphysics.org/viewthread.php?tid=696

g_day, You have certainly given us a lot to read---Thanks

And finally there are some good answers popping up in that link querying why the Universe didn't implode at creation due to overwhelming gravity. Basically two key factors:

1) It took a fraction of a second for gravity to come into existence and then another fraction of a second for it to try and propogate to reach an equilibrium state

2) in these fractions of a second the big bang had already gone too far for the Universe's own enormous gravity well to catch the expanding shock front.

Althought the sum of all the matter and energy in the Universe ( > 10 ^ 50 Kgs ) means a black hole with this mass should have an event horizon 40% bigger than the estimated size of the Universe today ( 40 billion light years ), by the time the big bang's explosion had grown from the size of a quark to say the size of an orange (end of inflationary period of creation) - most matter and energy had all outraced gravity.

So this trend continues and today alot of the Universe is so far away from its opposite side it is not only unreachable (even by light) - it can never casually affect us in anyway!

Begging your pardon, G__day, but that last paragraph is a bit overbroad. You are assuming that there is no force that could propel matter back at us at speeds that made light look slow. However improbable this may be, absence of proof still does not provide proof of absence.

Agreed, only within an Einstein framework there is no causality between many remote areas of the Universe. There may be many more things or forces we don't know that grant causality by allowing a far faster than light interaction.

But we have no theories yet to cover this, so we can't speak to their existence with anything approach authority, stay tuned!

Some good links to string theory and the unification of forces in the early Universe now in that thread btw.



From http://hyperphysics.phy-astr.gsu.edu/hbase/forces/unigrav.html#c1