imatfaal

Science is based upon empirical experimentation. Maths is based on axiomatic logic. Computer Science is - to my limited knowledge - axiomatic; therefore mathematical not scientific

I did a paper trawl and missed that one - not sure it ever made it through peer-review. There was a huge acknowledged error and a bit of a dog-pile afterwards with people spotting other sources of systemic and statistical error. Gravity Probe B was orginally noted as an F for fail remember - it was only when it was bailed out by the Saudis that any results could be gleaned from the data. I think there is still a strong will for a lense-thirring experiment which provides a nce clear slam dunk. Not that anyone serious doubts the results - but that is science for you; test, retest, and then work out how you can continue testing

I think Juno is gathering information as we type. Not sure I know of another one tasked to gather information about this phenomenon https://en.wikipedia.org/wiki/Juno_(spacecraft) If there is already a completed set of observations then it will be found at Clifford Will's site which I linked above From this article we can expect data set in October this year https://arxiv.org/abs/1302.6920

Measure tension - use an A-frame. String attached to apex. Legs angled towards fixed fencepost Weight attached to cross-bar. Angle of frame WRTo ground varies tension in string. Won't give you absolute value in SI units but a bit of trig will give you very nice relative values for different angles Measure time - you got a watch with a second hand? Or much better a smartphone with video. Download Tracker and use serious tools to get timings and shapes of waves - its free and pretty easy to use

Mantraphilter has been banned for a combination of reasons; hijacking, abusing staff, and a request for us to "kick him off this site for good"

! Moderator Note Hijack by Mantraphilter removed and locked. Please keep to the topic

! Moderator Note Mantraphilter Do not hijack threads with your own speculation.

Actual empiricism is always good. But you must be careful that your method and observations are able to disprove your null hypothesis Behold what? What was the method used to test the null - did you just hold a piece of string? And the shape it made was a catenary (or close to) rather than a parabola. See a scientist would either have looked that up (and given references) or experimented themselves - what they would not have done was give a bald assertion because that could have been culpably wrong and it is. [latex]y = a \cosh{\frac{x}{a}}[/latex] rather than [latex] y=ax^2+bx+c [/latex] https://en.wikipedia.org/wiki/Catenary So do you consider that your results show that the null hypothesis is not true?

News from today! Great Spot.

! Moderator Note Let's keep this topic to "Can a black hole explode?" - please move to new thread if you wish to discuss BBT and early universe and/or the missing matter problem

Sorry about moving this. Not sure I agree with the content - should have read it properly the first time then a) I would not have mistakenly moved it and b) would have responded. Surface Gravity - ie gravity of a black hole when at Event Horizon is not constant and varies with the size of the black hole. If we dente surface gravity as g then [latex]g=\frac{1}{m} \cdot \frac{c^4}{4G}[/latex] It is inversely proportional to mass and thus to radius - which in my layman's mind makes little sense. I can almost rationalise it thus; the curvature needed for there to be no exit can be mild (low gravity) within a big black hole but within a smaller black hole that curvature (and thus gravity) needs to be greater. In utterly simplistic analogistic terms that I cannot believe to be true - you can draw gentler curves wholly within a big circle than you can within a smaller one

Apologies. Done

Mathematically: Your third equation is a perfect representation of "why not" Logically: you could create more and more extreme examples. Your system would mean that: An absolute change has a greater and greater effect on the total population as the size of the population which has been changed diminishes - this is clearly logically flawed and can be shown by taking to absurd/extreme lengths. The numbers of people in my office has decreased by 66% today - the number of people in the rest of the world has decreased by .0001% therefore the number of people in the world in total has decreased by 66.0001%.

A 20% change in one population plus a 30% change in another population cannot be added to give a 50% change in a total population

Which said action would change the mass-energy of the BH - changing the position of the EH. On another tack: From a local inertial frame the photon must travel at c, there is no frame of the photon (regardless to your comment above that "every frame of reference is as valid as any other frame" - if you posit an inertial frame in which the speed of light is not locally c then you have contradicted one of the postulates of einstein's relativity and henceforward you cannot rely on the calculations of relativity), and for a distant accelerated frame (ie someone being held in position a distance away) the photon will either be redshifted to obscurity (but still moving) or by your claim will never reach them. So in what frame does it hover Final questions: What is a stationary photon - ie one not travelling through a medium at the local speed of light, what is its frequency if both c and lambda equal zero(undefined?), what is its energy from planck's equation if frequency is not clear

"As far as I know HR as generally accepted, occurs just this side of the EH, in particle pair creation event, where the negative falls in and the positive escapes to become real." This is very much a heuristic (ie not really true) explanation - the reality is vastly more recondite but I am not sure the details matter. But if the leeway for photon hovering is that small (ie that a particle/anti-particle pair are created with a separation beyond its realm) then how is a photon ever created AT the event horizon - they don't just pop into existence without something else happening. And the "something else happening" will affect the size of the EH and mean that the photon is now not AT the event horizon, just close. ! Moderator Note Sections of original thread ("BH Question") - and this one started by Robin to double-check statements within original have been merged

! Moderator Note Discussion on photon hovering etc moved to thread already discussing this matter - this thread to remain for OP http://www.scienceforums.net/topic/107085-light-near-a-black-holes-event-horizon/

Hadn't realised we were on two separate threads - I might have to merge

But Hawking radiation is predicted to be emitted - and that is precisely radiation which you talk about ie photons created at EH and outwards. If Hawking radiation stayed within the confines of the BH then blackhole evaporation etc would not function, BH would only get bigger, heat death of universe would not happen... Perhaps the HR calc's take this into account in the measure of luminosity - but I have never come across this idea of a stationary photon

“For instance, on the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much—the wheel, New York, wars and so on—whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man—for precisely the same reasons.” Douglas Adams - The Hitchhikers Guide to the Galaxy

The only stable place for photons near black hole is the photon sphere at 3/2 of the Schwarzchild radius - but as MigL says they are not stopped; they orbit at that distance. Others not in orbit either escape or loop back in. But describing what happens to an infalling test particle is fraught with trouble - what is position of observer, which coordinate system etc; gets conceptually harder when there is no inertial frame for the infaller

You're in Belgium - make beer If you do go for wine-making or brewing make sure you follow the sterilisation / cleaning procedures very carefully; the difference in taste can be remarkable. Sensei has some amazing videos of the cloud-chamber he made - frankly I think cloud-chamber is the best home experiment there is. A little work, not too expensive equipment, safe - and you get to see particle tracks. You can spot large energetic particles, cosmic rays, muons if you are lucky, and even decay cascades if you are the sort of person who wins the lottery

! Moderator Note ok thread locked. read the modnotes.

You don't. Plasma is a state in which particles have become ionized - ie electrons float free with the positive ions in a fluid state. Even before we reach the monumental crushing power of the gravity of a black hole we find that this state is not tenable. Neutron stars (which "crush" less than black holes ) have enough inward pressure to cause some electron and protons to merge to form neutrons - so this is the opposite of the free electrons of plasma; the pressure is so great that electrons are (to an extent) not even able to exist in the atom. we have precious little idea of what is beyond the event horizon. GR would tell us a singularity. QCD might mention things like quark or preon-degenerate state. But in reality we need a theory which deals simultaneously with gravity and the other forces all on a particle level and at very hi energy What you may be remembering is that black holes can generate plasma - and the plasma they can generate can be amongst the hottest stuff going. The material in accretion discs and polar jets is ridiculously energetic and almost completely ionised https://en.wikipedia.org/wiki/Astrophysical_jet

! Moderator Note Handy Andy For Heaven's sake - one topic per thread. Immediately after you had been asked to keep threads simple and on one theme you branch off into a whole new realm of speculation. DO NOT DO THIS AGAIN. If you want to ask about pair production then do so. This has little to do with strings. Which at your level of knowledge has no connexion to gravitons. Which in turn is only tangentially related to the notion of intrinsic angular momentum/spin. And that is only the first question. By your most recent post you are onto the heat / temperature of graviton gas! There is a lot of space for lots of threads - if you want to ask a question do so in a single thread with a straight-forward question if at all possible. If you wish to speculate then do so in the way prescribed in the guidelines - rambling threads with just a vague notion of an idea expressed in pop-science terms are not welcome. Ask as many honest questions as you want. But stop with the stream of consciousness - it is uneducational*, unwanted, and unedifying. Do not respond to this moderation within the thread *I know it is not a word but I like it