Holes Definition and 1000 Threads

Homework Statement An opaque card is pierced by two small holes 4 mm apart and strongly illuminated from one side. A lens on the other side of the card focuses images of the holes, 16 mm apart, on a screen 125 cm from the card. Find: (a) the position of the lens, (bc) the focal length. Why are...

[Moderator's note: Spun off from previous thread on different topic.] I'm still a bit new here and haven't studied much astronomy (being an electronics dude) so can anyone give me a good link(s) for what we know about existing black holes. That is size, location, and other physical...

http://arxiv.org/abs/1510.03066 String condensation: Nemesis of Black Holes? Michael Hewitt (Submitted on 11 Oct 2015) This paper puts forward a conjecture that there are no black holes in M theory. We will show that a mechanism to prevent black hole formation is needed in 4 dimensions to make...

Homework Statement Muscle can be torn apart by a force of 100,000 N applied across an area of 1 m2. A 10 cm2 muscle therefore will be torn by a force of 100 N. If a student of average size were being lowered into a black hole of 1 solar mass, at about what distance from the hole's center will...

This paper;http://arxiv.org/abs/1510.01733, Detecting Direct Collapse Black Holes: making the case for CR7, announce potential detection of a direct collapse black hole. Such a detection would shed light on questions such as the origins of SMBH and galaxies in the early universe.

Do these PBHs exist and would they lead to quantum gravity? http://arxiv.org/abs/astro-ph/0504034 Recent developments in the study of primordial black holes (PBHs) will be reviewed, with particular emphasis on their formation and evaporation. PBHs could provide a unique probe of the early...

Here is an oddball that I am wondering - could the spaghetification be countered by time dilation? Because as you approach a black hole (assuming you go in legs first) not only do your legs experience higher gravity than your torso, but they are also subjected to more time dilation - as they...

It heard it stated that light cannot escape from a black hole, yet light continues to propagate at the speed of light even in a black hole. Can someone explain to me how it can be that light can't escape yet does not slow down?

How does white holes curving the space-time manifold? (I prefer see picture of white hole influence in addition to the explanation).

In hawking radiation a black hole decreases in mass and is described by E= mc^2-GMm/r and as r gets closer to zero the energy of the particle that enters becomes negative and takes away from the net energy of the black hole. My question is why does this only apply to these particles that pop out...

If they are so insanely dense and their gravity is so mind-numbingly great, what prevents a neutron star from immediately collapsing into a black hole?

Hello Forum, An electric current is the flow of electric charge: charge in motion. The charges can be electrons, ions, etc. movingi in a solid, liquid, gas. When dealing with semiconductors the concept of hole is introduced. I understand that only the electrons are moving and the constitute...

I have some questions regarding things that boggle my mind about black holes. These things seem to me like paradoxes, and I was wondering if someone could explain them. 1. How do you measure the distance to a black hole? As far as I understand the distance to a black hole is defined as the...

My professor wants me to make a 15 minute oral presentation on black holes for an event we have going on on campus. How should I structure it? I think I have a pretty good understanding of the concept of a black hole, but I don't want to get caught off guard during the 5 minute Q&A section. My...

I mean, I'm making a game, not making a gamer. I talked about making a gamer with my wife but she just grabs my head, analyzes, sees how big it is and says "nah, thanks". (this paragraph made sense because the topic title was "any gamers here?I am developing one") Anyway, the title of the game...

Just out of curiousity, why is this? I'm reading this page right here: http://newt.phys.unsw.edu.au/jw/fluteacoustics.html#registerhole A dark hole on the flute means the button is closed, and each white hole means the button is open (open to atmospheric pressure). You can see from the...

this paper Do Black Holes End up as Quark Stars ? R.K.Thakur (Submitted on 25 Feb 2007) The possibility of the existence of quark stars has been discussed by several authors since 1970. Recently, it has been pointed out that two putative neutron stars, RXJ 1856.5 - 3754 in Corona Australis...

Since light is entirely incapable of slowing down, what happens when light approaches a black hole such that it's trajectory passes through the exact center of the black hole? It seems, based on what I currently know, this would mean that the gravitational force pulling on the light would be in...

For black holes to "trap" light, the light would need to enter into some sort of orbit, but it seems like that might have some odd implications with relativity. If light is revolving around the center of a black hole, that would mean the light waves/photons would constantly be changing...

Hello people, I have a question regarding black holes. The way i understand it, black holes form in supernovas, and they occur because the gravitational pull of the stellar remnant is so great that nothing can stop it, and it basically collapses down to a singe point, virtually nothing... Now...

So i was watching this video : And it got me thinking... i began wondering why, when space contracts from someones frame of reference (In the video, this would be the frame of reference of the cat), why is it that the protons don't become black-holes when the space contracts? If the density...

Do the black holes have infinite mass? If no then how can they have infinite density? Can we suppose that all the universe is orbiting a black hole (as heaviest masses bend the space time most) and loosing energy at some rate ?

A book I read says that when virtual particle-antiparticle pairs are created near a black hole then sometimes one of the particle pairs will be captured by the black hole while the other one will be freed to move away as a real particle - then this causes the black hole to lose mass and thus...

Hi, what is the percentage of Galaxies where we expect a central black hole? What type are those Galaxies? Thanks!

I'm designing a fixture for quality control and need a few precision holes. Their diameters range from 1/8" to 5/16" and need to be ±0.0002" with a depth of 1/2". I've been looking into EDM hole making and honing, but neither seem to be great for that range of diameters. Anyone know of any other...

Well, do they? Also: black holes, unlike elementary particles, have continuous distribution of rest mass, because they are free to absorb photons and gravitons of arbitrary mass, and kinetic energy of particles they capture. If two Kerr or Newman black holes have equal spin, which happens to be...

What particles that constitute the black holes?Does normal particles constitute the black holes? How can we calculate the ratio of types of particles in the universe(we consider known matter but not consider dark energy and dark matter)?How can we calculate the total number of particles in the...

Questions about black holes: Various articles mention that it takes infinite amount of time to observe something pass through the event horizon. Does this imply that the redshift observed from afar would carry on forever, that the infalling object would just become dimmer and dimmer, but never...

Hai pf, I had a doubt? we were well known about black holes still it act as a mysterious one. Well my question is about collision of two black holes. what happens if a highmass of black hole colloide with lowmass of black hole? Is the highmass black hole will suck the low mass black...

I have read articles regarding Chinese junks which utilise rudders made of rubber, and they usually have diamond shaped holes in them. These articles claim that the holes provide better handling of the junks compared to a full rudder without holes in them. What are your thoughts regarding how...

Black hole is considered an almost ideal black body by being a perfect black hole. But does it ideally absorb everything coming in the vicinity of its impact? Is it really possible for anybody to either ideally absorb or ideally radiate energy?

I have a problem understanding the concept of thermal expansions of solids with a hole in it. I do not want to accept face value the traditional explanation i am given that hole will increase in size because i am told to imagine if the hole was never cut. I fail to see the congruency in these...

http://arxiv.org/abs/1507.05760 Higgs boson cosmology Ian G. Moss (Submitted on 21 Jul 2015) The discovery of the Standard Model Higgs boson opens up a range of speculative cosmological scenarios, from the formation of structure in the early universe immediately after the big bang, to relics...

Homework Statement a black hole has schwarzschild radius of 15.4km what is the mass of the black hole in terms of the suns mass?Homework Equations Rsch = 2GM/c^2 The Attempt at a Solution I plugged values into the equation and isolated for M and it gave me a different answer. Idk how the suns...

I know that likening Black Holes to the Big Bang is common among laymen and that scientifically educated people quickly reply that they are completely different things. But I would like to understand better in which aspects are they similar and in which they are different. If we run the...

I have always been fascinated by black holes And I am sure that all the answers in physics are hidden in black holes... According to Einstein nothing can go faster than the speed of light, but nothing can escape black holes not even the light. Would it mean that the gravity resulting by a fall...

http://arxiv.org/pdf/1401.5761v1.pdf Abstract: It has been suggested that the resolution of the information paradox for evaporating black holes is that the holes are surrounded by firewalls, bolts of outgoing radiation that would destroy any infalling observer. Such firewalls would break the...

I just watched a popular science program entitled Super Massive Black holes that proposed the idea that galaxies were formed long ago from hydrogen gas clouds whose centers collapsed to become super massive black holes that then generated star formation and ultimately the formation of galaxies...

Classical calculated with Newton the escape speed is r = 2G.M/v2. With v = c that would be the same as the Scharzschild radius calculated with GR. Does that mean that Newton laws are still valid at (or just outside) this radius?

AFAIK black holes are factual, but i can not find physical proof of the singularity, apart from Einstein's theory of general relativity, which showed that when a massive star dies, it leaves behind a small, dense remnant core. If the core's mass is more than about three times the mass of the...

What happens to the higgs field around the event horizon of a black hole, or is this currently unknown? Does the higgs field permeate inside the event horizon? Can extreme gravity affect the field in some way by changing its properties?

Hello, I had a thought about the formation of white holes off of black holes and i wanted to ask if it is possible, if a massive black hole is surrounded by a lot of matter(a lot of giant stars etc.) and it consumes so much matter that even a aquasar is not sufficient enough in disposing all of...

black holes pulls light right, then when a black hole pulls photon will the speed that photon increase?

edguy99 submitted a new PF Insights post https://www.physicsforums.com/insights/animating-black-holes-singularities-infinite-force-gravity/ https://www.physicsforums.com/insights/wp-content/uploads/2015/05/graviytanimation-80x80.png...

ok, hear me out on a lymph, because I'm going to either be talking crap or something that sounds crazy either way... my question is: why does the phenomena of a black hole look so perfectly circular/spherical? now here's my reasoning spheres are the shape that takes the least energy to be...

It seems like when an electron moves to a higher energy level, even within the same band (conduction), the empty state should be a hole. But, we are told that in metals, electrons are the charge carriers. Do I just misunderstand what holes are? Or what is going on here?

Can someone please explain what a black hole is? I hear everyone speaking about it but have no idea what it is. Is it something where even speed of light becomes 0? How?

Hello, I remember hearing somewhere that it is possible to calculate the event horizon, I was just wondering if this is possible and what equations are used to calculate it.

All that I've read about black holes describe something so massive it's gravity overcomes all other forces and it causes a region of spacetime to develop that no particle or electromagnetic radiation can escape from. That explanation since it depends on mass makes no sense in regard to...

Homework Statement we look at a silicum n++ p+ n transistor. given: NE= 1,0×1018 cm–3; NB= 2,0×1016 cm–3; NC = 2,0×1015 cm–3; here E stands for the emitter, B for the basis and C for the collectorHomework Equations a. calculate the distance in eV from the fermi-level to EFi for the emitter...