billhinge

Roy Kerr who discovered the metric for real rotating black holes disagrees with Penrose/Hawking on the existence of singularities in real black holes, 'a foundation built on sand'. No quantum gravity required

Now mainstream ? If anyone knows then surely its the person who discovered the Kerr metric? https://arxiv.org/abs/2312.00841

I taught myself the maths and physics of GR to tensor level from the standard grad level books ( beyond what I did at 3rd year BSc specialisation) I don't claim to be an expert but I know my Riemann tensor from my Ricci\Weyl tensor from my Ricci scalar, my covariant from my contravariant and now that I'm about to be semi retired I'm going back to study for a physics masters to enjoy it with a 'desire' to to do further study afterward if possible (I can afford to self fund if required) . No need to find a job at the end or get involved in the typical student social activities 😉 I think criticism (I don't mean flat earth and other mystic woo woo) is an important part of science because it forces physicists to defend what they preach - they often disagree after all Do real physicists really have their feelings hurt if they are criticised on youtube?

Yes I appreciate that, point is that there are still many mysteries to solve, we don't know everything and we may even have got some assumptions wrong? (not picking on anything specific)

In radioactive decay the negative mass square is a consequence of conservation of momentum and energy of the resultant positron and neutrino (since thats its 'job') not a speed measurement. It isn't even an unusual result, there are some people who take this literally but most state that it is systematic error 'somewhere' since its 'obvious' that it cant be negative and there it must be positive. I make no claim for either viewpoint, my beef is that if there is systematic error then someone should identify where. The most successful standard model says neutrino mass = 0 and therefore must travel at c (but they can't since they oscillate).

Whats to misunderstand? Plenty of articles of varying technicality in google , question is why. I always remember this one because I did a third year project involving this and I also measured a negative value https://www.google.com/search?q=negative+energy+squared+of+neutrino&oq=negative+energy+squared+of+neutrino&gs_lcrp=EgZjaHJvbWUyBggAEEUYOTIGCAEQRRg80gEMNjI0NTQwNzBqMGo0qAIAsAIA&sourceid=chrome&ie=UTF-8

The energy squared (which is proportional to mass squared) of the neutrino is often measured to be negative in radioactive decay but within certain error and is taken as positive, it gets measured to be a negative number but there is just enough error in measurement that mass could be slightly positive by convention since imaginary mass doesn't exist.

While looking for articles on Black Hole volumes I found this interesting post from Roy Kerr (discoverer of Kerr Black Hole metric), quite interesting for the science and the human factor, reputation and how untested assumption can become uncontested fact...(maybe?, personally I've seen a lot of that in my line of work 😉 ) profile 'constructed the Kerr black hole metric, 1963. proved that the Penrose and Hawking singularity theorems are invalid, since their assumption that affine parameters cannot be bounded on a light ray is false.' https://www.quora.com/What-would-a-black-hole-look-like-from-inside-the-event-horizon 'If the body is stellar sized then it’s density will be roughly similar to that of a neutron star. If it is super duper sized then it is quite possible that the gravity will be earth like and so a ship could actually land on it. It could even take off again but will never be able to cross the inner horizon. incoming objects will be seen as they come in from the real world, no problem!' Also, surely all real Black Holes rotate so why do we talk about Schwarzschild BH's and their central singularity, shouldn't they all be Kerr BH's?

It could be if I/you are a boltzmann brain 😉

Sounds like inconsistent semantics, I'm sure people can find many instances so I don't have to much of a problem “When I use a word,’ Humpty Dumpty said in rather a scornful tone, ‘it means just what I choose it to mean — neither more nor less.’ I know what you are saying Yet we do say MOND Theory, String Theory, etc which hardly fit the above definition, yet Second Law of Thermodynamics and Entropy is a sacred cow and incorporated many theorems

Laws of Thermodynamics, Newtons Laws, etc?

isn't that what I just said? = "Let go, in free fall the pointer indicates 0 N." I didn't specify a specific height

yes provided you drop it from a height and measure the spring extension via video as it falls, doesn't work if its hanging

or you could just use an accelerometer or your mobile phone 😉

true, take your pick but the nice thing about many worlds is that there is a phone app for it 😉

Thats the issue with uni physics, they teach the maths but not "Foundations of QM' - I used to believe in Copenhagen but now switched to Many Worlds, you know it makes sense 😉

Is there a Newtonian gravitational force on the bottle & water or is it weightless in free fall ?

Admittedly challenging but you can do a few 'simple' mathematical examples (below) - there are 3 simplified problems at the end Plus if you understand Python there are a couple of libraries on GR https://docs.einsteinpy.org/en/stable/examples/Symbolically Understanding Christoffel Symbol and Riemann Curvature Tensor using EinsteinPy.html# Admittedly you need to get your head around relativity concepts and tensors first which may take several months if you are doing self study (you need proper GR books and read the boring small print about Einstein Summation Convention first 😉 ). I knew maths up to BSc level geodesics but GR is perfectly doable once you realise what you were taught about orthogonal unit vectors at degree level was a simplification and get Newtonian analogies out of your head (I found the forgetting Newtonian gravity ideas the hard part) Sean Carroll's video's don't shy from maths as he derives Einstein's equations but he gives excellent explanations of the reasoning behind them and the limitations Pop books while good for generating interest can equally confuse, but SC's pop GR book is good and a mix of maths starting from Pythagoras to the Riemann tensor akin to the following video simplified, but he also writes one of the standard text books on the subject if you prefer more maths

OK less biased, unlike humans it wont say I've spent $50m working on project X and devoted my life to it so I'm going to push model X regardless of whatever evidence is presented that model Y or Z is better.

The upshot was that there are many models about quark composition , each research team having their favourite based on personal bias. However the machine has no human bias so it compares the observation data with those predicted by models over the sum of all models. Thus seemingly ruling out what was previously most favoured and suggesting alternative models to 3 sigma so far.

When I did my msc back in 91 my project was on AI machine vision as it was called then. In those days we had to run on transputers and hand code everything in C and assembler to get any speed. AI was just a label Today as an IT architect I'm still doing interesting things with AI, ontologies, semantics, digital twins etc amongst other things... There is a concept known as the semantic triangle aka Ogdens triangle that relates labels to concepts and phenomena, provided you agree on concept and phenomena you can give it whatever label you like , eg 'temporal octopus training' since there isn't a standard label that maps label to concept/phenomena (we actually debated this at the ITU in Geneva several years back)

I think the whole AI debate is semantics, it is a back propagation convolution which I have no issue calling AI, the architecture is here https://docs.nnpdf.science/n3fit/methodology.html#neural-network-architecture code is opensource https://nnpdf.mi.infn.it/nnpdf-open-source-code/ Paper here https://arxiv.org/pdf/2109.02671.pdf

Interesting use of AI, wonder how many of our other assumptions are 'wrong'?

Provided you can afford it, better to find the big problems early on than later, last thing you want are intermittent faults later on

Are black holes watching you? https://www.quantamagazine.org/black-holes-will-destroy-all-quantum-states-researchers-argue-20230307/ In this “participatory universe,” as Wheeler called it, the cosmos expanded and cooled around the U, forming structures and eventually creating observers, like humans and measuring apparatus. By looking back to the early universe, these observers somehow made it real. “He would say things like ‘No phenomenon is a true phenomenon until it’s an observed phenomenon,’” said Robert M. Wald, a theoretical physicist at the University of Chicago who was Wheeler’s doctoral student at the time. Wheeler is one of the experts who wrote the bible on General Relativity