Markus Hanke

Since we have neither an established GUT nor model of quantum gravity (although there are various candidate models for both), we cannot at present tell what happened at the moment of the Big Bang itself. Our established models start being valid at around 10^-35s after the Big Bang - anything before that is hypothesis and conjecture at the moment. This is a distinct possibility, but it is not something we can - based on what is known at present - either confirm or rule out. Presently available data does seem to point towards this having been the case at some point (this would be called a GUT). Sure, it's a process known as spontaneous symmetry breaking. It's happened at the very least twice, probably more often. I hadn't mentioned charge in my original response. Anyway, charges of various kinds (electric, colour, isospin etc) arise from gauge symmetries of the field in question, so again they would come into being through symmetry breaking processes. Mass arises via the Higgs mechanism, so it only comes into play after the electroweak epoch. As to what specifically a GUT will look like - the jury is still out on this. There is quite a number of candidate models at the moment, and no real way to tell which (if any) would apply to our universe. Particles and their anti-particle counterparts aren't modes of excitation, they are separate and distinct fields. As mentioned above, charges (not just electric, but all types) arise from symmetry considerations. The Standard Model - even though it is evidently incomplete, and only an effective field theory of some more general underlying model - does a really good job in modelling the evolution of the universe from about 10^-35s or so onwards. Crucially, it has been thoroughly tested up to energies of a few ~TeV, so we know that it is a good and valid (albeit limited) model. It already explains how most of the particles we can observe today come into being, along with the necessary mathematical framework. It is all quite plausible.

None of this makes any sense in light of what we know already. First of all, “particles” are not fundamental to reality, they are just excitations of the respective underlying quantum fields (which are the fundamental entities here) - so there is not even any problem to be solved, since the only difference between having one particle of a kind, and many particles of the same kind, is the mode of excitation of the same underlying field. There is no such thing as a gazillion electrons in this universe - there is, and always has been, only one electron field, with the appropriate local excitations. This is well understood, and not an issue. Secondly, “number of particles in a region of spacetime” is not an absolute thing, it is an observer-dependent quantity; this does not seem to be accounted for here. Thirdly, prior to electroweak symmetry breaking, the Higgs mechanism wasn’t in existence yet, so at the early stages of the universe’s evolution all particles would have been massless and thus moving at the speed of light. This precludes the existence of vastly massive “super particles” that are somehow orbiting one another. Again, this is well known and understood. So essentially, this author (whom I have never heard of) attempts to solve a problem that doesn’t exist, in ways that are contradictory to already known physics. Yes, there are problems left to be solved in modern cosmology, but this here isn’t a viable approach.

I’m sorry to say, and without meaning it personally, but...this is really just word salad 😕

Me The first PC (if you can call it that) I ever owned was a Commodore C16, featuring...wait for it...16kb of RAM. Yes, that's kilobytes. Taught myself BASIC back then...later I progressed to a ZX Sinclair, then to an Atari ST, where I taught myself C, MODULA-2, PASCAL, Assembler, and Lisp. Very nostalgic memories of spending days and nights trying to implement things that programmers nowadays would only laugh at! Was a great time, though.

You can express it either as a distance in m, or as a time in s, by using the speed of light c as a conversion factor. You are ultimately completely free to choose whichever units work best for a given problem (so long as they are used consistently of course). I don't think it does. You need to also specify a metric; in particular, the metric signature plays an important role here, namely that time and space have opposite signs within the metric.

I think you know which one I meant: In both cases you are essentially asserting that Maxwell’s equations are not valid, so this is just a repeat of the same thing.

I seem to remember that, when your last thread on this topic was closed, to not bring this up again.

Could I perhaps suggest a very short (few minutes) video on the invariance of the spacetime interval:

Yes, though perhaps not visually. But you would still be able to detect the gravitational radiation emitted by such an event, since gravitational waves cannot be shielded by ordinary matter.

Purely algebraically, this can only be true for L=0 (trivial case), or for v=c^2 (physically impossible).

There are no guarantees here. The best we can do is make the assumption that whatever finds the message has a roughly similar sensory apparatus as we do, and that their mental processes are roughly similar to our own; we can then attempt to construct a pictorial or auditory message in the most general and (to us) universal of forms, and hope for the best. Over and above that, all bets are off. The thing is that all languages are social constructs - words, sounds and pictograms mean to us what we take them to mean because everyone within our social context agrees that they do mean that, and we have been taught those particular conventions in early childhood. Even amongst us humans it can sometimes be very difficult to communicate certain ideas and concepts outside of a given social context, and our attempts at communication with other species in the animal kingdom have met with at best limited success. Communicating to an alien species that may share few or even none of our cultural and social conventions could be exponentially harder still - and potentially disastrous, should we get it wrong. In the worst case, the alien race may be sufficiently different in terms of sensory apparatus and mental processes that there isn’t even a common channel for communication, never even mind a common language. I don’t know how such an encounter would pan out.

Right...all the best with this, then.

In the twin paradox, there is always acceleration in one of the frames, even if just for a very short time on a very short section of the world line. If there is never any acceleration in either one of the two frames, then it is not a “twin paradox” type of scenario. It is the very presence of acceleration - no matter how short in duration - that destroys the symmetry between the two frames.

\(\pi\) is not equal to 22/7, this is just a convenient approximation. So no, you can’t express any arbitrary transcendental number via rationals.

As an uninvolved and largely silent reader, I got a very different impression - that you think you understand relativity, but actually you are just shoehorning specific relativistic phenomena into a Euclidean worldview (not very successfully, I might add). You have not yet understood on a deep enough level that the world simply is not Euclidean, except as an approximation in the low-energy, low-velocity domain. I am also getting the impression that you are not prepared to even entertain the possibility that the world might not in fact be Euclidean. No, thank you. As stated previously, I have no wish to involve myself in this discussion. I am also able to rigorously see on the highest level, using simple linear algebra, that it is mathematically impossible to construct any kind of physical paradoxes within the axioms of SR, so I do not have any need to find errors in specific scenarios, because the very existence of such errors means that the proponent of the scenario has failed to apply the model correctly. It’s like a third grader getting his long division wrong - their getting the wrong answer doesn’t mean that long division isn’t a valid operation; it means they haven’t used it right. Relativity is just the same. And in both cases, it is best to get them to understand the bigger picture before letting them loose on specific problems. This is what I mean by top-down approach. I’m sorry to be so blunt, but you are just wasting your time with all these specific use cases. You need to get out of your Euclidean mindset, or else none of this will ever make any sense to you.

A TOE is a model that - at least in principle - would be able to describe any phenomenon in the real world under one overarching framework; or to put it differently, it’s a model that would be able to produce all the various sub-disciplines of physics as limiting cases. This also includes disciplines that don’t naturally arise from the field theories of the Standard Model (and its various extensions) alone, such as thermodynamics for example. It is possible that quantum gravity might turn out to be the same as a TOE, but at the moment these are taken to be two different - albeit closely related - things. It is also possible that such a thing as a TOE might not exist at all.

I presume what you are actually referring to is a model of quantum gravity (a TOE is a different issue altogether). There is a standard framework to turn a given classical field theory into a quantum field theory - this prescription works just fine when used on the electromagnetic, weak and strong interactions. However, if we attempt to apply the methodology to gravity, the result is physically meaningless, because it is full of infinities (as MigL correctly stated, the result is not renormalizable). One part of the problem is that the other interactions happen in spacetime, so spacetime is kind of a necessary fixed background against which the physics play out; gravity is different in that regard, since here spacetime itself is where the dynamics happen. There are other reasons why this does not work, but most of them are quite technical.

In an age where information is abundant, fake news are rampant, and all sorts of conspiracy theories abound, having a modicum of scientific knowledge will help the average citizen to better judge what is genuine information and what is simply BS. Ignorance is the greatest enemy of the common people.

Presumably an omnipotent being would have no need to observe the quantum system, he could have knowledge of its entire history without having to collapse it first. Since that knowledge is not accessible to us, this case would be indistinguishable from God not existing.

I would not necessarily agree with this - I think as you get older you develop more wisdom, but not necessarily intelligence. Exactly how do you define 'smart'? I think it is context and experience, which is something that can only be developed with time (and circumstance). For example, a young medic fresh out of university may know everything there is to be found in medical textbooks - but standing on the bedside of someone with (let's say) unusual or non-standard symptoms, he may still not be able to diagnose them correctly, since he lacks the experience to put that knowledge into a wider context.

Almost all of the work he did is of a highly mathematical nature, and much of it (e.g. singularity theorems) can be rigorously proven. I have not read all of his papers, but those parts of his work that I have seen are of exceptional scientific value - so his reputation as an ‘authority figure’ is well deserved, IMHO.

I don’t know what would help Michel. I seem to remember he’s an architect by trade (right?), so he would have been explicitly trained and experienced in thinking in Euclidean terms, since this is the kind of geometry we use to construct everyday objects. But relativistic spacetime is not Euclidean, so maybe this is where the problem lies. The geometry of Minkowski spacetime isn’t particularly abstract, it’s just different from the kind of geometry we learn at school. But when one does not make that paradigm shift away from Euclidean thinking, nothing about relativity will ever make much sense, irrespective of whether the particulars are understood or not. I don’t think so lol Relativity really isn’t that difficult to grasp, and Michel is clearly very intelligent, so I don’t think the problem is one of understanding.

I don't really wish to involve myself in this discussion, but there is one point I'd like to make - from my personal experience, I found that a top-down approach works much better when learning relativity. That means you start with the general overarching principle, and then drill your way down and see how those apply to individual scenarios. Getting yourself lost in complicated scenarios seems not the right way to go. But maybe that's just me

Gravity (in the universe we live in) is always a property of 4-dimensional spacetime. If you are far enough away from the black hole, the Newtonian inverse-square law will be a pretty good approximation; but the closer you get, the less accurate it will be, since the geometry of spacetime deviates more and more from being flat. The maths of GR are more difficult because it is a highly non-linear theory, and you are dealing with a (potentially large) system of coupled partial differential equations; so this is a completely different ballgame, compared to the simple vector calculus of Newtonian gravity.

Note that this is true only so long as the falling frame is small enough - the equivalence principle is a purely local statement. Once the frame becomes large enough, it will be possible to detect tidal effects, which are inherent in a gravitational field that is due to sources of energy-momentum.