billhinge

Yes I posted in the history section, the 456 page book is out next week (1st Sept)

In case anyone is interested the 'Apollo Remastered' 456 page book is released on 1st September from the usual places ... https://www.bbc.co.uk/news/science-environment-62662685 I remember when I was at infant school in the late 60's you could collect the labels from spaghetti hoop tins (C&B I think?) and send them in to receive large poster size photographs of what I think may have been Apollo 8 or 10? Hoping they are in the book as I used to have those on my wall and was looking for reprints

gravity on the ISS is actually 89% of the surface gravity, it just appears to lack gravity due to free-fall . We feel the moon's gravity and vice versa in tides I think the problem is the mixing of newtonian and relativistic concepts of energy. In GR there is no clearly defined concept of potential energy . The previous question is then answered by the person lifting the weight gets hot through doing work The problem with learning is the analogies we get taught initially get engrained so it becomes difficult to shake. Took me ages to shake the newtonian model out of my head, same with covariant/contravariant vectors (at school you get taught euclidiean geometry and vectors look like A=5*i + 6*y + 7*z etc and the basis vectors i, j, k are at right angles to each other) and they don't even mention tensors other than pretend they are funny matrices 'A Youtube video asserted that mass bends time, and bent time causes gravity.' Thats a good one isn't it , think its semantics 😉 - causes gravity? or causes to fall etc ?

Always hated that expression, by whose definition do we choose?

Did you dismantle the corrector ? If you want to do it yourself you can buy the Hotech laser https://www.firstlightoptics.com/hotech-collimation-tools/hotech-advanced-ct-laser-collimator.html bit expensive now at £450 which you may wish to compare vs price of professional service, postage and insurance You need a steady surface and mount plus about 3m of dark space (and a second tripod for the laser)

It was her debunking of the delayed quantum eraser which was the clue, I wanted to know what her beef was and why some comment accused her of misinformation so did some googling 😉 Notice how she states her assertions are universally accepted interpretations. Another clue was her apparent idolising of that guy again who was famously anti QM Even in GR land there are disputes over why apples fall under gravity Is an apple falling under gravity caused by time dilation at the earths surface or is the earth accelerating up to hit a falling apple? (or are people using the wrong language) go ponder 🙂 Recall the 2017 Jim Al-Khalili BBC documentary (free on amazon prime) in the last 5 mins at 1:22 when he quotes Kip Thorne saying matter moves to where it ages slower . (sorry the documentary is called 'The Amazing World of Gravity' in case you want to watch it)

You seem to have a thing about Sabine 😉 , I'm not saying I agree with everything she says and I know a lot of what she implies as fact is based on her belief in her super-determinism but she also says a lot that people can relate to and IMHO I enjoy the directness of many of her videos (everyone is selling something and she is a good sales person) The issues here are not necessarily science/academia but human nature. Whenever you get tribes of people, even in industry it is difficult to get traction if your 'idea' doesn't fit the 'plan'. I've lost count of the number of crap projects that trundle on because of sunk costs, loss of face etc. (Fortunately I have/had jobs which allow me to call them out) My view is that if you are confident in your product you can defend it adequately, if you can't then you don't have as good of a product as you think. If mainstream physics don't like Sabine's social media then perhaps they should have their own social media outlet. Working in particle physics is a privilege that not many have, so maybe Ed Whitten should be telling the public why tax payers should be paying their taxes to support his ideas if they are so great. Not being open gives the impression that something on the inside stinks and the tribe would like to keep it private. The taxpayer may ask why am I paying to support this esoteric research and shouldn't the money be better spent on NHS, climate change, etc (pick your own good cause) Having said that I don't begrudge funding physics through my tax £ but others may

Worth a read is Shell Beach https://jespergrimstrup.org/blog/ A third unfunded contender for a theory of everything behind String theory and LQG is Quantum Holonomy, and it is hated by both groups if you read the book, even if it shares some aspects of LQG dna (its the wrong kind of math), the author seems to say that research is very tribal. It appears to be maintained by a team of 2 who struggle to get traction with mainstream physics. I don't know if its correct, but it is a compelling 'start from the bottom' with no assumptions approach and claims to show gravity is NOT quantum in nature and the standard model can be derived from first principles (and black holes have no singularities)

I posted 15kg of weights (3) wrapped in bubble wrap in a shoe box wrapped with T-Rex tape, thankfully it arrived intact, hopefully no one dropped it on their foot!

As an alternative view I guess it depends on what you want to do, do you want a qualification and letters or understand a subject mathematically in more depth and your starting point. I'm assuming a reasonable amount of physics and maths knowledge is assumed if you are mentioning M.Sc's I was lucky enough to get a degree in astrophysics when they were free so I learnt physics & math techniques (mostly forgotten), but the thing I disliked was the focus on the 'how to derive an equation and put numbers in and turn the handle' rather than why, how does that work in relation to observed physics? e.g What does a path integral mean anyway and why use that rather than another integral. In those days there was no internet and the only source of info was the library or lectures, now we have great info online and arguably better presenters of information. Recently I went down the route pondering should I go for another degree but then I remembered, some subjects were boring (or at least the tutor was) and I focused on those subjects I liked In the end I went the DIY route to teach myself (which is straightforward enough if you do maths revision etc, even after 40 years its funny what you can remember. In someways it's easier to understand than when you are 20 with loads of stuff going on). At the moment I think I have a reasonable mathematical understanding of Riemannian geometry, Christoffel Symbols and Schwarzchild metrics and how to apply them, better than my 3rd year understanding of GR anyway. The fact that there are no deadlines, exams, time pressures makes life easier I find. (Also doing Quantum Field Theory, not the old particle in a box stuff- my uni professor never did answer my question as to why you don't use Schrodinger hydrogen perturbation theory for helium atoms, so what do you do instead, why use Hamiltonians vs Lagrangians etc 😉 ) I'm nearing retirement so no aspirations job wise and I'm doing it for my own interest

Maybe, but the point I was making was that it is possible to use computational tools to see what are the key factors that an AI learnt and by what percentage each factor matters It's not a leap of faith to me to use the above analogy with physical models and parameters. Problem I see is that if we try to understand gravity, would it learn Newton or Einstein or GR hybrids if we teach it with a falling apple vs satellite vs black hole? The AI's conclusions would be influenced by its observations and accuracy (and experimenter's bias) surely - as would ours?

Sounds pretty cool to me, there were similar projects for financial markets. If you believe in technical analysis, which TA indicators are were more significant impacts on price . eg https://deepai.org/publication/bayesian-regression-and-bitcoin If you are familiar with AI and github its fairly easy to try yourself When I was a first year undergraduate one of the first questions discussed in tutorials was working out factors that influence a system and how they are proportional to the result. Sounds like an AI version of that Lots of food for thought

How am I patronising you? I don't know your qualifications I'm just trying to be civil and clear and I'm not just writing to you personally but to all the other readers of this thread I thought I was clear, a spectrogram is a special mirror therefore it fails the test of direct measurement since your system source, mirror, detector.,the same as a traditional 2 direction measurement of light. QED describes the spectrogram part and why you are not measuring a direct A->B measurement Anyway I've said what I intended, so best call it a day

Thank you, nice website! Let's go back to the beginning. The article states 'The speed of light is an assumption, not a certainty. It’s an assumption in that we have never experimentally measured the one-way speed of light. ' I responded to say, yes, in fact its baked into Einsteins original paper! (I also posted a video that discusses this, the fact that QED, not just Quantum Theory but Quantum Field Theory is not mentioned is not relevant as we were just talking about the challenge of directly measuring A to B vs B to A ) Most reasonable people would agree that the universe is isotropic (you quote Occam's razor which is a reasonable response), but the issue is do you accept that it is isotropic based on faith or do you try to prove it? The article and my response asserts that the speed of light in one direction can't be measured directly measured. No one disputes that you can calculate 'a value' from an equation which includes fundamental parameters but it doesn't demonstrate experimental measurement of the one way speed of light Your counter-argument seems to be that you have devised an experiment to measure the one way speed of light My response was, you haven't since you have used a diffraction grating which is just a specialised mirror - these effects are fully described by QED (see 'The strange theory of light and matter' by Feynman) True, using QED to explain diffraction, reflection and other effects involving light interacting with matter is using a sledge hammer to crack a nut, but Huygens etc are just analogies that give the same results in a way you use Newtonian mechanics rather than general relativity geodesics to describe earthly motion of projectiles. But don't mistake Huygens and Newton for reality. When you know that light is being affected by matter you need to understand mirrors are quantum mechanical in reality! (interestingly QED explains why your telescope secondary doesn't block the star in the centre of your field of view or why holes don't leave gaps in your telescope image - go read reddit or cloudy-nights if you want a laugh at the hand waving arguments). Since we are really in the realm of QED, we know any measurement affects the original state. So to summarise, your use of a specialised mirror means you haven't measured the 'one-way speed of light. '. I don't dispute the accuracy of your measurements and what you have created with your website etc is highly commendable. Strictly speaking since diffraction gratings are made of atoms you should also try gratings of different materials to see if there is any effect there I'm sure I won't convince you but it may convince some to dig into this subject further, 🙂 (the feynman book is cheap and part text chapters, part maths, path integrals, probabilities and Feynman diagrams and there are some semi technical videos on the subject) cheers steve

You are using a 'diffraction grating', which is essentially the same as a mirror at the atomic level. ie photon scattering by atoms hence not a one way trip - refer to Feynman QED, you have chosen to adopt a classic approach which still gives the same answer (nothing wrong with that) Indeed the photon being diffracted and measured is not even the original one being emitted. How does your method differ from the MM expt which also uses mirrors? I don't say the speed of light 'isn't' isotropic so why do you assert I'm a believer of alternative universes and physics? Proof and belief in assumption/axioms are subtly different

you are missing the point, sure you can calculate a value for c from other formula such as Maxwells eqns etc but the question was about measuring directly using distance and time - refer to Einstein I can (and most others do) measure the square mass of a neutrino to be a negative number but we choose to say the error on the calculation is just enough to to make it a small positive number and hence not an imaginary mass when square roots are taken. This was my final year grad project study on radioactive decay many years ago, neutrino mass being an easily calculated by product based on conservation of momentum. But it wasn't a direct neutrino mass calculation.

Hi The issue is as follows, Einsteins original paper states this is an assumption (by definition) ! 'We have not defined a common “time” for A and B, for the latter cannot be defined at all unless we establish by definition that the “time” required by light to travel from A to B equals the “time” it requires to travel from B to A. ' https://www.physics.umd.edu/courses/Phys606/spring_2011/einstein_electrodynamics_of_moving_bodies.pdf (page 3 top para) I don't think many dispute or believe c is different in different directions, but it's there in black and white, you can't prove it, you assume it. You always need a two way trip, even MM relies on mirrors There is a good Veritasium on this

Thanks both, so the choice is a seam or zits? 😂 I'm happy with how it turned out but I may try printing again in carbon fibre PLA as I want to teak a couple of tweaks to strengthen the OTA join - only held by 3 small bolts! Cheaper than paying £200+ for a custom metal jobbie I had planned to sand and paint anyway but I was just curious (I'm using Qidiprint which is a Cura clone, its updated fairly regularly and usually does a good job so haven't bothered copying all the settings across to Cura) I may use the remains of this roll of PLA on v2 of my cycloid gearbox, measurements weren't quite right last time, couldn't get internal wheel to fit properly with the dowels I used this blueprint https://www.ewhiteowls.com/2022/02/the-ultimate-guide-to-design-cycloidal-drives-the-beating-heart-of-robotic-arms/ for the cycloid

I printed the full adapter but given the heavy weight of a 3.7" focuser, Riccardi flattener and other kit such as cameras, is straight plain PLA tough enough. I have carbon fibre PLA as well just in case, or could do nylon if required. The PLA does seem very rigid, I can't bend it by hand, walls are about 6mm thick. Any idea what causes the straight ridge on second image, it isn't in the model? The adapter slides over the focuser and into the OTA tube

Step 1 complete Measured inside/outside of TMB LZOS 115 Kruppax tube and outside of new APM 3.7" R&P focuser (to replace existing 2" Feathertouch) accurate to 0.01 mm - got close with a micrometer and kept increasing size by few hundredths till I got a tight fit. No one makes an adapter this size and it would cost a fortune for a custom job so DIY is best Final Prototype 'rings' now correctly measured and fitted snuggly against OTA tube and focuser - holes all line up Needs to support either Riccardo flattener etc so now to design the bit between the tube end and the focuser and make a bit thicker This is printed in thick PLA which I plan to flock with protostar and paint (got some Mosou Black to try - good excuse 😉 ) Also printed a cycloid gear box but measurements are out slightly, needs tweaking and reprinting printer is Qidi X-Max PLA seems quite rigid

Here is a link to a site showing Hubble vs Webb https://bigthink.com/starts-with-a-bang/universe-before-jwst/

NASA’s James Webb Space Telescope has produced the deepest and sharpest infrared image of the distant universe to date. Known as Webb’s First Deep Field, this image of galaxy cluster SMACS 0723 is overflowing with detail. Thousands of galaxies – including the faintest objects ever observed in the infrared – have appeared in Webb’s view for the first time. This slice of the vast universe covers a patch of sky approximately the size of a grain of sand held at arm’s length by someone on the ground. This deep field, taken by Webb’s Near-Infrared Camera (NIRCam), is a composite made from images at different wavelengths, totaling 12.5 hours – achieving depths at infrared wavelengths beyond the Hubble Space Telescope’s deepest fields, which took weeks. The image shows the galaxy cluster SMACS 0723 as it appeared 4.6 billion years ago. The combined mass of this galaxy cluster acts as a gravitational lens, magnifying much more distant galaxies behind it. Webb’s NIRCam has brought those distant galaxies into sharp focus – they have tiny, faint structures that have never been seen before, including star clusters and diffuse features. Researchers will soon begin to learn more about the galaxies’ masses, ages, histories, and compositions, as Webb seeks the earliest galaxies in the universe. This image is among the telescope’s first-full color images. The full suite will be released Tuesday, July 12, beginning at 10:30 a.m. EDT, during a live NASA TV broadcast. Learn more about how to watch. https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-delivers-deepest-infrared-image-of-universe-yet

If you want to be OTT and tinker more, you could choose ABEC 7 grade bearings https://www.skf.com/us/products/mrc/precision-abec-5-and-abec-7-bearings Some skateboarders swear by them (I'm not a skateboarder), lots of ABEC7 skateboard videos on youtube. Its up to you whether you 'believe' or not The worm bearings are easy to find but the big bearings can be £80 each !

I would be tempted to try https://www.ebay.co.uk/itm/193592991803?hash=item2d130aa03b:g:DOIAAOSw0SxfGtat&amdata=enc%3AAQAHAAAA4M4fESIOVpM4AfPZgMpi5H5QYHh3mNPYPNNE%2BqD506Sb3HBbCJq2MTwHaMA%2B1ZgcsvUW%2F%2B%2FCVMj%2FaV6RWMZnlz8bjAc%2BF4LweN18YDfkyoAUG3oTb%2F9Kh6IsfLJuwZWnXKiVnVvnbqMx8JQvMVztBSntSyikkAw%2FUMF3IWKp%2FrODLTpJ6GdCbnyeD%2Fn56xgMbN44%2Bz%2B2zNw4nWeTWeXurvWRCwbrm22ZscttQJhfKFMvGs69HYqSi3SyRlXG%2FmjeL9WFn9G1IKNxHerZBTKUjvawc1bEcsFEYJk34MfH7zjp|tkp%3ABFBM7sbGobJg. if I didn't have the 100% pure stuff both grease and dry powder bought from the US some years ago. You can even put it on teflon to make it slippier! Or you could go all in for powder coating and run everything dry https://www.ws2.co.uk/

Price on two well known UK sites is now £2450 which seems very reasonable