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I was reading through Mordred's long standing thread on space and I came across some posts from Mike in the early part. Members may wish to know that Mike passed away earlier this month after a long standing degenerative illness (not covid). Mike was an interesting character, an artist with a degree in Physics and the founder of a successful manufacturing business before retirement to Cornwall. His artistic (dreamy) side gave him an unusual and sometimes frustrating perspective on Physics, especially later in life when we knew him. But he was a genuine character and sometimes offered suprising insights as well.

It seems highly unlikely that you would be able to explain observations and experimental results regarding gravity using electromagnetic theories. But please feel free to post your attempts. General Relativity is well established. If you are aiming at replacing that theory with something that has the same predictive power but is based on electromagnetism then my guess is that the probability of success is zero. Some quick notes: Gravity can't be shielded. Gravity is not modelled as a force in General Relativity Elementary particles with zero charge are affected by gravity Etc. Experts in this forum may also explain more fundamentals regarding the mathematics of tensors; source of gravitation is a second-order tensor, the source electromagnetism is a first-order tensor

Hope this helps.

Hello, Its been a couple of years since i came up with this idea. Just want to share with you a video that i made explaining this theory. Basically, it is explained from an electrostatic perspective of a neutral atom that i call the neutrostatic field. It is the parasitic electric field from a dipole atom that we consider 'neutral'. But both charge is not occupying the same space at the same time so the net field cannot be absolute zero at any distance from the atom. Since the positive nucleus and the negative electron is separated by the bohr radius, then their is always a net weak field in any space around it. Currently I'm attempting to do some simple calculation to support this theory and will share the result once finished. Let me know if this theory has some potential, thanks.

Just when you thought you could sleep at night... An asteroid more than a mile wide will pass by Earth on Wednesday while travelling at a speed of about 19,000 miles (30,578km) an hour. The space rock, known as (52768) 1998 OR2, is expected to make its closest approach at 10.56am BST, when it will be just 3.9m miles (6.3m km) away – about 16 times the distance between the Earth and the Moon. Although the asteroid is classified as a potentially hazardous object (PHO), scientists have said it will not pose a danger to the planet. Dr Brad Tucker, an astrophysicist at the Australian National University, said: “This asteroid poses no danger to the Earth and will not hit – it is one catastrophe we won’t have. While it is big, it is still smaller than the asteroid that impacted the Earth and wiped out the dinosaurs.” Source: https://www.theguardian.com/science/2020/apr/29/asteroid-passing-earth-1998-or2-wednesday-near-4m-miles-face-mask-fly-by

Agreed, that's the way I see it also....In case I did confuse anyone when I said It is our models that are real, and have best and accurately described what we observe as close to reality as is possible. Something does not have to be physical to be real imo. I'm an old bugger too.

When discussing coordinates sytems and metrics is is important to realise that they are independent concepts. A space can have a metric but no coordinate system and vice versa. References to topological spaces have been made. Topological spaces do not require coordinate systems and some topological spaces do not require a metric. What is required for GR is continuity for the equations to make sense and the tensors to exist at all. Mathematics now separates continuity into several allied concepts ( coincidentally all beginning with C) and I did promise Joigus a thread on the subject. I suppose this is now becoming urgent.

IOW, down-hill is just a direction...

That is a myth for the most part. Friedman had a great quote for that: It is the assumption that jobs are a fixed commodity and hence increase in labour would decrease its value. However, it is in fact elastic. With more folks entering the workforce, consumption also increases, which in turns stimulates the economy. While there can be depressing effects locally and short-term, the effects long-term and globally are usually either neutral or positive (i.e. net increase in wages) based on empirical studies. For example a paper by Weinstein (2017; J Reg Sci 57:4 591-610) found after adjusting for regional differences that an increase in labor participation of women in the workforce between 1980 and 2010 increased wages, for both men and women.

I'm an old person too, Col. yes, IOW = in other words I believ I was the one who originally mentioned the need for a co-ordinate system, back on page 11 of this discussion. Maybe my idea of a metric is not the same as yours Markus, and if not please elaborate so that we may all understand better. Is the metric not a measure of the deviation of the co-ordinate space ? It surely isn't a measure of actual deviation in 'real' space. (IOW, space-time has no actual 'fabric' that bends )

This is where my head was UNTIL I read that previous post of yours. “Nah, they were just there like at a rally... sure, they doubt the election results, but whatever. They’re just regular old Tom, Dick, and Sally’s out holding signs and taking photos.” But you made a point that gave me pause... that made me view things differently. Majority of them DID want to overturn a free and fair election, to throw away votes they didn’t like, and circumvent the process. That in itself is a type of sedition. It’s a desire to overthrow our democratic principles and our republic. Sure, everyone exists along a spectrum and some were more aggressive/extreme than others who were meek and mild, but NONE of them were there supporting our legal processes or allowing the justice system to sort through the claims of fraud. The sincerity of their beliefs isn’t relevant. They felt they knew better than those in charge and were acting like vigilantes who desired to replace the actual election results with their own personally preferred winner. In short, they were trying to overthrow our government. That’s a well made point I can’t simply ignore or dismiss. Dude, I’m an experienced wood worker now. I wear safety glasses. No splinters in these eyes. Matthew 13:13 Therefore I speak to them in parables: because they seeing see not; and hearing they hear not, neither do they understand

Interesting but somewhat confusing. You want a differentiation between the mathematical description, and actual, physical space. You have stated we have the mathematical description, but haven't yet tackled what we mean by actual, physical space. IOW, we have the model, but what is the actual reality ? ( and Dad says we don't know, which you agree is valid ) I would assume, as a scientist, you know how science works. We build models ( mathematical models, not toys ) and test them against reality to find their limited areas of applicability. The only model that is 100% applicable is the reality itself. I have to ask, how else would you model actual, physical space, if not mathematically ??

Couldn't agree with you more, Ken. Because violence ( and other crimes ) remain illegal, no matter how noble the cause. I realize you're trying to 'educate' me, INow, but I have to quote Matthew 7:5 to you ( and because I think Biblical quotes would annoy you ) "Thou hypocrite, first cast out the beam out of thine own eye; and then shalt thou see clearly to cast out the mote out of thy brother's eye." But I appreciate your efforts, brother .

As a lay person with an interest in science and the scientific methodology, my perhaps simplistic view is as follows....Space is what exists between you and me, or between the planets and their stars. Time is what stops everything from happening together and the means by which the intervals between sequential events are measured. Spacetime is the four dimensional framework against which we locate and calculate events. The concept of spacetime follows from fact that the speed of light, "c," is constant and does not vary with the motion of the emitter or the observer. It is essentially a description of reality common for all observers, while at the same time, the measured Intervals of space and time when considered separately will vary between observers and different frames of references. Gravity of course as GR tells us, is the geometry of spacetime in the presence of mass/energy. All are essentially real: Space is expanding and the source of what we know as Dark Energy. Time is essentially interchangeable with space and is a variable quantity. Spacetime can be bent, warped, curved, lensed in the presence of mass. Any errors, alterations or corrections? Please be gentle with me. 😜

Dr. Yamagishi and his team came to this conclusion by placing dried Deinococcus colonies on display panels outside the ISS. Samples of various thicknesses were exposed to the space environment for one, two, or three years, and then tested for their survival. Three years later, the researchers found that all colonies larger than 0.5 mm had partially survived in space. Observations show that although the bacteria on the surface of the aggregate died, it created a protective layer for the bacteria underneath, ensuring the survival of the colony. Using survival data after one, two, and three years of exposure, the researchers calculated that a granule greater than 0.5 mm thick could live 15 to 45 years on the ISS, thus proving the possibility of natural interplanetary transfer of microbial life that would otherwise called panspermia.

An alternative proof from direct Taylor expansion in the metric coefficients and counting how many parameters are left that I cannot set to zero by changing the coordinate system: https://www.youtube.com/watch?v=gf-G4QiAHLY&list=PLaNkJORnlhZnwjIXnOHrX50FEyoyiTh4o&index=5 Those must coincide with the number of independent components of the Riemann. \( \frac{1}{12}n^2\left(n^2-1\right) \) Uses Young tableaux, which allows you to count free parameters very easily.

Let’s look very briefly at what the symmetries of Riemann actually constrain. We have two sets of symmetries - first, those that are present even in the absence of a metric: \[R{^\alpha}{_{\beta \gamma \delta}}=R{^\alpha}{_{\beta [\gamma \delta]}}\] \[R{^\alpha}{_{[\beta \gamma \delta]}=0}\] \[R{^\alpha}{_{\beta [\gamma \delta ||\mu]}}=0\] Second, we have metric-induced symmetries: \[R_{\alpha \beta \gamma \delta}=R_{[\alpha \beta]\gamma \delta}\] \[R_{\alpha \beta \gamma \delta}=R_{\gamma \delta \alpha \beta}\] \[R_{[\alpha \beta \gamma \delta]}=0\] What this means: in dimension n, every index pair can take on n(n-1)/2 independent values (due to their anti-symmetry), which initially leaves us with a symmetric matrix with \[\frac{1}{2}\left(\frac{n( n-1)}{2}\right)\left(\frac{n( n-1)}{2} +1\right) =\frac{n( n-1)\left( n^{2} -n+2\right)}{8}\] independent components. The Bianchi identities (last relation in non-metric symmetries above) constrain a further n!/(n-4)!/4! components. This finally leaves us with \[c_{n} =\frac{n^{2}\left( n^{2} -1\right)}{12}\] functionally independent components of the Riemann tensor. In n=4 dimensions, this evaluates to 20. So on a spacetime manifold with 4 dimensions, the symmetries of Riemann leave 20 tensor components unconstrained and functionally independent, meaning those components are not identically zero in the general case. Hopefully this clears things up, since it is trivially obvious that geodesic deviation does in fact exist in the real world (contrary to the OP’s claim), just like the theory says it does.

If you had stopped there, I would have given you a +1 also. Unfortunately you misguidedly went on about 'whataboutism', when some of you guys are the biggest offenders. Anytime JC or I ( and a few others ) mention mis-steps by American progressives/Democrats, your first answer ( as well as Swansont, Phi, and a few others ) is always "But the Republicans do much much worse; they can't even be compared. So why are you even bringing it up ?" If you can't think of the times you've done this, I can post numerous examples/quotes. If that is your attitude, it is going to be a boring 4 years in the Politics Forum. Everytime someone criticized the new Government, your first response will be "But D Trump did much worse during his Presidency." And then I'm told I have biases

Yeah. Let's make it clear that taking over parts of cities using intimidation and violence, and excluding authorities and police, can only reasonably count as "protest" and not insurrection. Orwell would be proud. Can we not condemn both violent extremes, regardless of whether we believe one is worse? Does not condemning one not help ignite the other? Or 1936, the Spanish Civil War. Absolutely brutal and based on ideological extremism, with atrocities common on both sides. This is what we are capable of. Not directed at anyone: Can we not condemn both violent extremes, and be a little more tolerant towards those in the middle seeking civil discourse?

Someone, said "kruger"...

I guess the answer is science doesn't know. Why guess?