So, p_k, Outsider, what do you think of

[Brainfade]

Stephen Hawking casting doubts on the existence of black holes? http://www.nature.com/news/stephen-hawking-there-are-no-black-holes-1.14583

Most physicists foolhardy enough to write a paper claiming that “there are no black holes†— at least not in the sense we usually imagine — would probably be dismissed as cranks. But when the call to redefine these cosmic crunchers comes from Stephen Hawking, it’s worth taking notice. In a paper posted online, the physicist, based at the University of Cambridge, UK, and one of the creators of modern black-hole theory, does away with the notion of an event horizon, the invisible boundary thought to shroud every black hole, beyond which nothing, not even light, can escape.

[punjabi_khota]

I don't know much about this topic.. I just hope Hawkings hasn't gone bonkers, that is all.

[dial_100]

There is definitely something where the matter collapses in the middle of the galaxy. Isnt it? This particular area does not emit any bright light. So its difficult to prove that there is no such black hole in there. If not what is it?

[diga]

senility takes over sense as one ages

[The Outsider]

Firstly, it is important to understand what a Black Hole is in scientific terms. In a simplistic language it is lots and lots of mass compressed in a very tiny volume. The theory which is applicable to the property of mass is the General Theory of Relativity (GTR). The theory which is applicable to very tiny volumes is Quantum Mechanics (QM). Both are hugely successful in explaining a myriad of natural phenomenon. One of the biggest challenges of Theoretical Physics is that GTR and QM are not compatible. That essentially means when you try to find out how gravity behaves at very small distances the Mathematical equations diverge and give a whole bunch of infinities. A Black Hole is a place in nature where a lot of mass is in a very tiny volume ie. a natural playground for the interaction of these mutually incompatible theories. Now coming to Hawking's work - he has not said Black Holes do not exist. He has said that the Event Horizon, a prediction of GTR, does not exist. I haven't checked the mathematical rigor of his work, being out of academia I am restricted in my knowledge, motivation, and time to do so. There are hazaar more qualified people than me who will do it. Assuming, his mathematical rigor is correct, the work is an alternate exploration in the behavior of a lot of mass in a tiny volume. There is very good evidence for the existence of Black Holes, but pretty much nothing about the dynamics of an object near what has classically been referred to as the Event Horizon. This is not the first effort to go there, but possibly because he has sought to get rid of the Event Horizon in his work and it comes from Hawking, the media has twisted it as getting rid of the notion of the Black Hole in itself, which is just a lot of mass in a tiny volume and certainly does exist. Just that we don't know how mass behaves in those realms.

[The Outsider]

Just to expand on my previous post a bit, an Event Horizon is the place where the compatibility of GTR and QM breaks down. We have never known what happens beyond it and there are many esoteric and non-esoteric scenarios. Hawking is saying that once you come to the so called Event Horizon, it really does not exist and proceeds to give an explanation of what happens in that realm. The Event Horizon is a classical GTR concept and there is no fundamental reason it has to hold as thought about till now.

[avicric]

Hawking the most over rated man after rohit sharma

[Muloghonto]

Hawking the most over rated man after rohit sharma

:haha::haha: He is a living legend. Not only the most accomplished theoretical physicist of the 20th century after Einstien and Plank, he is a medical miracle too. IIRC, Hawkins is the *only* person ever documented to've gotten his neural paralysis condition and survived for more than 10 years. In other words, he's made it to 40+ years with this paralysis where the second-longest most lived person with this condition died less than 10 years after getting it. Probably the greatest mind with the greatest handicap to overcome.

[vvvslaxman]

Hawking the most over rated man after rohit sharma

:cantstop:

[seedhi]

Just to expand on my previous post a bit, an Event Horizon is the place where the compatibility of GTR and QM breaks down. We have never known what happens beyond it and there are many esoteric and non-esoteric scenarios. Hawking is saying that once you come to the so called Event Horizon, it really does not exist and proceeds to give an explanation of what happens in that realm. The Event Horizon is a classical GTR concept and there is no fundamental reason it has to hold as thought about till now.

I remember reading a book (Brief History of Time) where Hawking argued that Black holes are not actually "black", they radiate energy and lose mass constantly. The reasoning being that the second law of thermodynamics would be violated if I just throw something with large entropy into a black hole which does not radiate anything out. Apparently, there is some quark level process going on at the event horizon which leads to this radiation.

[CSK Fan]

I have some amazing insights into this but since the OP only wanted Outy and PK.......

[randomGuy]

I have some amazing insights into this but since the OP only wanted Outy and PK.......

:cantstop: Blackhole doesn't let ligh escape its gravitational field and a black cloth also absorbs light and reflects none. Can we say they are similar in this aspect ?

[Old guy]

:cantstop: Blackhole doesn't let ligh escape its gravitational field and a black cloth also absorbs light and reflects none. Can we say they are similar in this aspect ?

But black cloth does reflects light ..that's how u see it

[randomGuy]

But black cloth does reflects light ..that's how u see it

no yaar, black colour means either the absence of light or the complete absorption of light.

[Muloghonto]

no yaar' date=' black colour means either the absence of light or the complete absorption of light.[/quote'] No. You do realize that light and x-rays are the same thing, right ? They are both EM radiation that work exactly the same way ( both in terms of energy dynamics and wave-partical duality). The only thing they differ in, is frequency- as every EM radiation type does with each other. A black hole probably consumes probably 99.9999999999% of any radiation incidental on it. A black cloth only absorbs the visible spectrum of light to appear black. It does not absorb most of the higher or lower frequencies of EM.

[randomGuy]

No. You do realize that light and x-rays are the same thing, right ? They are both EM radiation that work exactly the same way ( both in terms of energy dynamics and wave-partical duality). The only thing they differ in, is frequency- as every EM radiation type does with each other. A black hole probably consumes probably 99.9999999999% of any radiation incidental on it. A black cloth only absorbs the visible spectrum of light to appear black. It does not absorb most of the higher or lower frequencies of EM.

of course. By light, i meant the visible light.

[Old guy]

of course. By light' date=' i meant the visible light.[/quote'] Black the color ur describing is also visible

[randomGuy]

Black the color ur describing is also visible

eyes can't differentiate between darkness and black objects

[randomGuy]

^^Suppose there is a closed dark room n it's bright outside the room. There's a very tiny hole in a wall n you look into tht hole from outside the room. If the opposite wall's colour is black, then you won't be able to tell whether that is the end of the room or its an infinitely long room. But if the opposite wall is any colour except black, you can tell for sure tht it'snot an iinfinitely long room

[Old guy]

eyes can't differentiate between darkness and black objects

true but its still totally different from blackholes which suck up even photons :cantstop: you cannot see them scientist observe them by seeing their effects on surroundings i think