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OK, I have my 59th Old Boys reunion coming up shortly.....a right royal piss up it looks like being. As the only one interested in cosmology to the extent that I obviously am, three of the more interested old farts have asked me to properly describe BH's. So here it is..........Any errors, alterations and/or corrections recommended by our on line professionals is welcome? BH's of sorts, were hypothesised to exist in 1789 by John Michell. This Newtonian variety were called "Dark Stars" and did have a surface just below where the density of the relevant matter, had an escape velocity equal to "c". His work was not taken seriously and was pigeon holed until many years later when Neutron stars were discovered and questions were asked about further possible collapse of stellar objects. Arthur Eddington called them a cosmological absurdity. GR and its equations predicted their outcome, yet Einstein originally thought that there would always be a physical barrier to prevent such catastrophic collapse. When a star uses up its available fuel for fusion, it has one of three paths to take, based on the original mass of that star. It can end up a White Dwarf as our own Sun will eventually see out its life. These WD's are held up from further collapse by EDP [Electron Degeneracy Pressure] Larger mass stars finish their lives as Neutron/Pulsar stars, held up from further collapse by NDP. [Neutron Degeneracy Pressure] Inevitably even larger mass stars are monstrous enough to overcome both EDP and NDP, and forming what was to be known as Black Holes. First known as Gravitationally Completely Collapsed Objects, John Wheeler coined the BH. Simply put a BH's EH [Event Horizon] is where the escape velocity equals "c" the speed of light in a vacuum. Beyond this point nothing can escape, including light. A BH's size can vary from those predicted to have occurred at the BB, microscopic quantum sized BH's, to stellar collapse BH's a few 10s of kms in diameter, and the monsters that lurk at the centers of galaxies ranging from millions to billions of solar masses. These are termed Super Massive BH's. BH's can only have three properties of mass, charge and angular momentum. Charge would obviously be quickly negated, leaving mass and angular momentum. Angular momentum also would gradually be negated, but over much slower rates. This leaves the end state of all BH's in the distant future, as the Schwarzchild variety, or a BH with no spin or charge, also the most mathematically convenient to work with. If we were to categorise all the BH's we have in our Universe today, the most common would be the Kerr BH, or the one with angular momentum, first suggested by Roy Kerr. GR tells us that once any massive object is forced to undergo collapse, once it reaches a point called the Schwarzchild radius [which for a BH is the EH] then further collapse is compulsory. This means that if we squeeze the Sun inside a volume of around 5 kms diameter, it would reach its Schwarzchild radius, further collapse would continue and it would become a BH. Once a stellar remnantcollapses to or below this radius, light cannot escape and the object is no longer directly visible, thereby forming a BH. It is a characteristic radius associated with every quantity of mass. The name itself results from Karl Schwarzchild a German astronomer, who calculated the exact solution during the first world war in 1916. This compulsory collapse leads us to what we refer to as the Singularity. Mathematically speaking, the Singularity is where all our known laws, including GR break down, or are not applicable. Most cosmologists today worth his salt, accept that this mathematical singularity and associated infinities, does not really exist. Rather a surface of sorts just at or below the quantum/Planck level should exist. This is where GR fails to tell us anything. Many other seemingly weird aspects of BH's are known, but as weird as they are, they are aligned with the facts borne out by SR/GR that space and time are not absolute and that all frames of references are as valid as each other. An example of one of these seemingly paradoxical scenarios is as follows...... If myself and a companion travel towards a BH and I stay a safe distance away, while my curious friend travels on towards the BH and its EH, due to gravitational time dilation, I will from my position in space, never see him cross the EH to his doom, only slowly and gradually just redshifted beyond my instrumental viewable ranges. From my friends point of view though, he proceeds towards the EH, and crosses it with no changes from his perspective in time, ignoring tidal gravitational effects which depend on the BH's size...the smaller the BH, the more critical and sooner will be the effect of spaghettification as it has become known. Both views, mine and my intrepid friend's are as valid as each other. Physically speaking the Singularity lies at the heart of the BH, and is where all its mass is concentrated in a form that as yet we have no description for. It lies at the quantum/Planck level of spacetime, and may in the future have more light shed upon it by a validated QGT [ Quantum Gravity Theory] A quantum effect called Hawking radiation which theorises on particle pair creation at near a BH's EH, where one escapes and the other succumbs to the BH, tells us that over the lifetime of the Universe, BH's should evaporate. Hawking radiation though, just like BH's have never been observed. Though we still have some that will claim that BH's do not exist, none can ever describe the effects on matter/energy and spacetime, that are observed in any other logical scientific way, the effects that can only ever be attributed to BH's. BH's for all intents and purposes, and based on the current laws of physics and GR, and as evidenced by recent gravitational waves discoveries, most certainly do exist. If not then some other even more incredible unbelievable object is present. Likewise Hawking radiation, and what we know about the quantum world, tells us that logically it is a real concept, but in most cases, would be only evident over the lifetime of the Universe, and we are talking time frames of many hundreds and even trillions of years. Stephen Hawking once used a phrase from a poem by Dante, about the gates of Hell. "Abandon all hope ye, that enter here" probably aptly describes a BH. Would a bunch of old 74 year old farts accept that science?

Why? Everyone disagrees with you. Pointing out the difference in perceived intelligence between 500 council estate born labourers and 500 city born stock brokers is a cultural difference not a racial one. Are the stock brokers more intelligent because they can do better on an IQ test and wear nice suits? There is no racial difference between them - just social and economic. Are the labourers superior because they are physically stronger? It is about their upbringing and back ground and life experiences and privilege. Take any of the labourers and give them the same upbringing as the toffs and they would look. sound and behave the same. Any actual racial difference are so small they are negligible - but you get people, who get described as racists, that try to take these minute differences and try to justify their supremacy fantasies and political agendas. Did you read any of Sensei's posts? Looks like you ignored them or were just blind to them - many have said the same thing.

I am where I am... simply passing through the Universe...

Under the facade that is our social face we are all weird in our own way.

We certainly shouldn't assume that there is. As I explained earlier, you need faith for this imaginary conclusion, so you are still basing faith on faith. Besides, I fail to see any logic in the supposed reasoning that follows.

! Moderator Note This is NOT mainstream physics, so I'm moving it to Speculations. It's really doesn't have enough science to survive there either, but you'll get better feedback on some of your misconceptions. Filling in gaps (ignorance) in the pattern of your knowledge is something humans are really good at. So good, that if we don't actually know something, we often make up something pleasing that makes perfect sense only to us. That cognitive bias is one of the reasons the scientific method was developed. It helps us remove as much wishful thinking and emotional guesswork as possible. Anytime you think anything is 100% certain and true, you probably aren't doing science. It's awesome that your brain is so good, but you're driving that Ferrari out in the weeds, dude. You should bring it out on the Autobahn, better known as mainstream science. It's made for Ferraris.

It's a given in your problem. Given by you. It's the event. That's a solution for science fiction writers, not for discussing the scenario you have offered. No, it's not built on that. It's a conclusion of it. Causality being real is the foundation, since we have independent confirmation that relativity is an accurate description of nature. As some people put it: Relativity Causality FTL You get to pick two.

Etymology. The word "toff" is thought to come from the word "tuft", which was a gold tassel worn by titled undergraduates at the University of Oxford or the University of Cambridge. The Anglo-Saxon word "toforan" has a meaning of "superiority"._Wiki

No, that's not causality being broken. But consider that scenario, where you see the effect before the cause. Let's say the cause was pushing a button, and the effect was something bowing up some distance away (so there is a signal delay) You could then send a signal to the button-pusher to tell them not to push the button, and they would get it before they pushed the button, and decide not to do it (or to someone else, who cuts the wire; in any case, the bomb would not explode) Now you have the situation of having observed the explosion cause by the button being pushed, but the button was not pushed. The actual scenario of causality violation involves two (or more) reference frames, and sending signals between them http://www.askamathematician.com/2012/07/q-how-does-instantaneous-communication-violate-causality/

In which case, you should acknowledge what science has to say about the concept of race and update your thinking accordingly. https://www.nationalgeographic.com/magazine/2018/04/race-genetics-science-africa/

As a younger man I "dumped" a lot (relative to my own experience) of girls. Looking back it was me that was the problem. Every girl I ever dated was actually very nice and it is a shame they wasted their energy on this jerk, hahaha. In my experience (limited by gender, national culture, years of earth, etc) when an individual who is otherwise capable of meeting a mate remains single in adulthood the issue is with them and not with others. Some people do prefer being alone but often it comes down to an inability to truly empathize with others and share ones true self. I have never been on a date with someone perfect nor am I perfect. While on a date one can choose to enjoy it or not. When a person agree to date another it a rather big compliment when you stop to think about it. While on a date you are with someone who in theory has a high opinion of you. Turning that around into judgments about their intelligence is a bit petty. Dumping, kickin' to the curb, ghosting, and etc someone who simply likes you is immature behavior in my opinion. Not everyone is meant to be together but there are polite ways to end things and reflect upon them after they have ended. * I have been married for 10yrs now and barring some unforeseen circumstance will be for the rest of my life.

I can't make out what you want from this thread, you have so many ideas mixed up along with not a few gripes. Perhaps this thread would be better in the General Philosophy section, it certainly isn't about modern and theoretical Physics. So I will comment on one point you made. In Science (including Maths) one important way we learn about things by observing the how they interact with other things. To compare two (or more) things we can use this by replacing one thing with the other in these interactions and observing the differences. Numbers are no different in this respect so to tell the difference between two numbers we can put one in place of the other and see what happens. Would you prefer I gave you £1 or £100 ? In fact you are strictly correct. There is no detectable difference between 0.9 recurring and 1. But the 9 must be strictly recurring ie not terminate at some large count of 9s. That is the count is infinite. Note that the number itself 0.9 recurring or 1 are both finite. If the count is finite the that number is less than 1.

Of course! One can never really doubt the words of Issac Newton...."I see as far as I do because I stand on the shoulders of giants" [or words to that effect]

I'm going to assume that English isn't your first lanquage. A pulse is a type of signal with regards to time dilation is is identical to signal propogation delay in an electronic circuit. The pulse RATE will vary not the number of received pulses. In other words the wavelength between pulses will vary as well as the duration of each individual pulse So no it does not prove no time dilation occurs but merely proves you don't understand what is involved with regards to pulse rate vs number of received pulses.

Silvestru and Koti - just cross the border into the least religious country in Europe...

The first 50 mins of this excellent Sean Carroll lecture will give you a good overview of the scientific evolution of the first ideas of particles through to them being seen as fields and how they work, including an explanation of what the Higgs Boson is about that gives things mass. Beyond the 50 minutes he goes into where physics is going. You don't need much prior knowledge to understand what he's saying.

Could I take it right back to the beginning? In the beginning studiot said that, if the bottom of the lake was flat, the surface of the lake could also be flat. Does studiot stand by that? In the above post it seems that he is now saying something different: "If the bottom is flat the water surface cannot be different from flat by more than the depth." That makes sense to me - though wouldn't it also be true that the place where the "difference from flat" is equal to the "depth" would be called "the shore"? It does seem that evidence has been presented to show that the shape of the ocean floor does affect the shape of the ocean surface. But it doesn't seem that evidence has been presented to show that a shallow lake which is flat on the bottom would have a surface whose shape is in any way influenced by that.

I will ditto this. By "reference", what I guess Michel means is a link to a study in which the shape of the bed of a body of water is shown to impact on the shape of its surface. In another post, for example, you linked to Seasat. Does that mean there is somewhere where we can read that Seasat measured what you are saying?

Hello, maximillian, I think the Wikipedia link I provided to seasat and subsequent satellites was in the other thread in post#202. I did post further information from another (fully referenced) textbook here in this thread in post #12 which described the calculation used by seasat and subsequent satellites to determine the distance from the satellite to the water surface. The original Seasat information I provided was in post#197 of the other thread http://www.scienceforums.net/topic/98386-laser-curvature-test-on-lake-balaton/page-10 and took the form of a measured (by seasat) world ocean surface relief map showing the measured surface which clearly shows the bottom features reflected in the surface topography. This is a public domain image produced by the seasat team, which I took from another textbook, "Image Interpretation in Geology" by Drury, along with some other explanatory text which Michel seems to object to. Because many are confused by the nature of the geoid I provided a simpler newtonian mechanics explanation of why there is a dip in the cente of a large enough lake and why a hump in the water surface tends to spread out sideways or level itself out, in post#2 here. The usual explanation involves vector calculus on potential surfaces and spherical hamonic theory. It is also important to note what is meant by a 'gravity map' Most are not absolute values but show deviations from some theoretical shape, which is why the scales run from +100m to -100m in Michel's references. I have also fully answered his query in the post immediately preceding yours with reference to the Wikipedia article in post#12 by Mordred where it states explicitly what I have said. Have you thought about my question posed at the end of post#17 If the Earth were perfectly spherical, homogeneous and isotropic, what would be the shape of the geoid? Here is a hint. The geoid is not completely governed by gravity.

Are you posting this in the right thread? Local surveys of the lake should surely be discussed in the lake Balaton thread? However I did answer your questions in post#19 here in this thread. Was there something there you did not follow? Remember that my objective was to do a 'back of an envelope' estimate of how much the water surface might vary so design a suitable survey method. This estimate suggests that gravitational effects will affect the surface by less than 20mm.

Not that there is anything wrong with his ideas, only that they were honest thoughts about the observations that he made.

It's supposed to show that Einstein was honest about racial differences and acknowledged them instead of pretending they don't exist.