Register to reply 
My Top 10 Questionsby PaulMurphy
Tags: None 
Share this thread: 
#1
Jun3011, 07:24 PM

P: 7

1. In Leonard Susskind’s “The Black Hole War,” he says that if radiation has a wavelength larger than the event horizon of a black hole, it will bounce off instead of falling in. I've never read this anywhere else. Can anyone here discuss this topic further?
2. Based on how dense the energy and matter was immediately after the big bang, for how long after the big bang was the escape velocity greater than the speed of light, and thus, the entire Universe was inside the event horizon of a black hole? 3. If gravity was a repulsive force at the singularity of the big bang, why is it not repulsive at the singularity of a black hole? 4. How can a singularity be said to rotate when it has no spatial dimensions? 5. Black holes are described as having a mass, but isn’t 100% of the mass in the singularity itself, which has zero volume? If this is the case, then I think 100% of the volume of the black hole inside the event horizon would have no mass. 6. How does matter ever get to the singularity from the event horizon if time slows to a stop at the singularity? 7. What happens as a string gets close enough to a singularity to experience a time gradient severe enough to distort its vibrational wave pattern? 8. Does the speed of light have any relationship to any process that generates electromagnetic radiation? For instance, does the quantum of energy needed to create the longest wavelength radio wave equal the smallest quantum of energy released to place an electron in the lowest energy orbit? 9. Could the speed of light be a property of spacetime rather than of matter and energy? 10. If all forms of life are entropy engines, taking in low entropy energy and giving off high entropy energy and the arrow of time is the direction pointing toward greater entropy, could a living creature’s perception of time be due to their being entropy engines? 


#2
Jun3011, 08:09 PM

HW Helper
P: 3,448

2.There was very high density everywhere, so there was nothing to 'escape from'.
5.The singularity doesn't have zero volume. Its just small. 6.Once the singularity has been established, no more matter goes into the singularity (from our perspective). 9.Both. 10. Could be. Or that could be a coincidence. 


#3
Jun3011, 09:14 PM

Mentor
P: 11,892




#5
Jun3011, 09:20 PM

Mentor
P: 11,892




#6
Jun3011, 09:25 PM

P: 15,319

Oh. I see what he's saying. It's flawed logic: If the mass has zero volume, then a larger volume that contains that mass is 100% massfree. Therefore ... the mass at the centre ... has no mass. The flaw is that he first grants that a mass could have zero volume, but then goes on to conclude that, if a volume contains that mass, that the mass can't have mass ... why? because it's zero volume. 


#7
Jun3011, 09:28 PM

Mentor
P: 11,892




#10
Jun3011, 10:33 PM

P: 7

Thanks for all the replies. I learned a few things already. Here is some clarification:
3. Who said gravity was a repulsive force? I read about inflation theory in Brian Greene's new book, The Hidden Reality. There is a whole section about repulsive gravity, the inflaton field and negative pressure. In summary, he said the force that caused the faster than light expansion of spacetime during inflation was repulsive gravity. 5...I think 100% of the volume of the black hole inside the event horizon would have no mass. Why? Your logic does not follow. What I was trying to say is that if a singularity really has zero volume and 100% of the black hole's mass is in the singularity, then 100% of the volume of the black hole within the event horizon would be empty space (except for the background noise of virtual particles caused by quantum uncertainty). I'm creating a contradiction on purpose to show that I don't really believe (yet) that all the mass inside the event horizon truly occupies zero volume yet can still directly interact with exterior spacetime via gravity. 7. String? As in string theory? Yes, again Brian Greene's books. He says that the strings of string theory vibrate in the extra dimensions and based on the given CalabiYau shape they vibrate in, the vibrational pattern gives the particle its properties. A string vibrating in one pattern would be an electron, in another pattern a photon, etc. I'm wondering if one part of the string is in a slower flow rate of time frame of reference than another part, would that cause distortion to the calabiyau manifold and change the particle's properties? Say it was vibrating as an up quark and as it gets very close to the singularity, part of it would be vibrating in a different flow rate of time than the rest. Does it become a new type of particle? 


#11
Jun3011, 10:38 PM

P: 15,319




#12
Jun3011, 10:51 PM

Mentor
P: 11,786

Paul, trying to discuss ten questions in a single thread is a surefire route to confusion and madness. Questions on different subjects should be in different threads.
Also, most of these questions really belong in other forums than this one (Quantum Physics), IMO. I suggest: 1, 3, 4, 5, 6: Astrophysics 2: Cosmology 7: Beyond the Standard Model 8: Relativity or Quantum Physics 9: Relativity 10: Classical Physics or maybe Philosophy 


Register to reply 
Related Discussions  
College questions, electrical engineering questions, and more  Academic Guidance  8  
Ways to differentiate homework/textbook questions from regular questions  Forum Feedback & Announcements  4  
ExaminationStyle Questions. Density of Material Questions (b)(i)(ii)  Advanced Physics Homework  5  
Comments about an issue in cosmology?  Cosmology  10  
Two questions  Special & General Relativity  14 