joigus

Very good question. +1 A quick scan of, https://books.google.es/books/about/The_Global_Approach_to_Quantum_Field_The.html?id=-LtutgAACAAJ&redir_esc=y (The Global Approach to Quantum Field Theory, Volume 1 By Bryce Seligman DeWitt) Allows you to find only a couple of paragraphs where space and time inversions are introduced on a coordinate-patch basis. Nothing like the predictive power and generality of CPT in flat space-time is suggested. For all I can remember, the context where CPT is really powerful is the S-matrix approach. And defining assymptotic states in a curved space time is problematic, to say the least. Searches on other more modern books, or on Quantum Field Theory in Curved Space-Times, also by Brice DeWitt, haven't produced anything that remotely resembles "CPT". Not even mentioned AFAIK. I do not think there is anything like CPT valid for curved ST that is remotely as robust as it is in flat ST. But I would be very thankful if anybody knows. This is very interesting, because it connects with my question following up on a suggestion by you on the thread about "What is time?" Would you have some licence to consider signature-preserving continuous transformations that re-shuffled the space-time coordinates, of which our T, P transformations were a discrete version?

OK. Not that it's interesting to anybody, but I was raised in a Catholic country, and had to do away with a lot of cultural/religious/mythical/ceremonial baggage. I tend to mistrust my own opinions very often; let alone other's. I did that at a very high price. The brain can be a crook. It likes to show to you pleasing landscapes. It likes to prove you right. It also tends to have you accept propositions just because they will make you fit in socially, or stand out. I don't trust the brain's inertial forces. I suppose I'm just a runaway from belief towards degrees of certainty.

That's not what I said. Here's what I said: Can you read it now? Take some time. Read it twice, three times, if necessary.

You believe too much with too little evidence. AAMOF, you believe I believe something. Not only that; you go on to assert it, as if you were privy to my mental states. You couldn't be farther from knowing how I form my opinions. Which goes to prove that you give too much value to your beliefs. I don't to mine. Neither I do to yours.

Thanks a lot for your drawings and explanations, @studiot. +1 The only reason why I would wait a little bit before totally endorsing your picture would be that, if anything, QFT has shown us that whatever it is that we perceive as space and time must be very deeply connected with the space of charge. After all, it's the composition of the 3 inversions (CPT) that produces a very robust discrete symmetry of Nature. But I see no a priori reason why the "internal" dimension of charge could not be added to your picture. Very interesting your rescuing Eddington's observation. It is so interesting that I will re-type it here: (my emphasis). I couldn't agree more. But, in fact, it amounts to something both you and I (at least) have already (at least) implied: IOW: describing relations between points in space as intrinsic, with no oriented parameter. And, AAMOF, I have implied it too. Here it is: Maybe I didn't say it explicitly, but my point was that it is the first, the implicit picture, that is more objective. The oriented parameter t in this picture would be, let's say, just psychological, instrumental, etc., what have you, and have nothing to do** with what goes on in the physical world at large. That objective reality would be described by the intrinsic interdependence of states. The parameter would be just an artifact you need to introduce if you want to account for your experiencing the world as an ordered sequence of configurations. Nothing more. I wouldn't dare to call it emergent, but maybe immersive (more related to how the observer experiences the world). Now, using the arc-length on the curve gives you a natural parametrization, defined except for its sign and a family of infinitely many re-parametrizations. I think most of us here would be closer to common ground for agreement if we made it as clear as possible what we mean.*** ------------------------------------------------------------- * I shouldn't have said "clear-cut" here. After all it's an infinite family. ** Well, not "nothing to do", but a lot more to do with what goes on in the observer's mind, measuring instruments, etc. *** (Edit): This is rather meant as self-criticism, as I don't think I've been as clear as I could have, going back to my previous posts.

Universe did a pretty nifty job of looking as if it had existed long before any intelligent observers were around. That's all I can say.

+1. Very interesting, meaningful and inspiring conversation going on here. I only wish to emphasize observation by @Duda Jarek that charge symmetry can indeed be formulated either locally or globally.

Maybe of interest: https://www.forbes.com/sites/startswithabang/2017/01/26/how-the-anthropic-principle-became-the-most-abused-idea-in-science/#efcb4a57d690 The anthropic principle is tautological. Tautologies are not necessarily bad in physics. They can never be false. What could be more robust than that? But when you depart from a tautology, you need at least a second assumption that gets you out of the circle. Example: Newton's second law rests on a tautology. Mass and force are introduced at the same time, so you have no way to define mass but as based on force. And force cannot be defined without invoking mass. Were it not for the fact that people* related force to position through the concept of potential energy, and additional assumptions on its parametrics, nobody would have been able to get out of the loop. *Starting with Newton himself.

Looking forward to it. You're probably right. You just can't change the rules. But you can change the names. So, what tells you which one of the four directions is time if you know nothing else? Let us remove any sequential notation that suggests an ordering, like t, x, y, z or a, b, c, d, etc., and make the argument clearer. Let's say your event coordinates are: \[\otimes,\boxplus,\oplus,\boxtimes\] Which one is time? If some "angel" told you the metric is: \[\otimes^{2}-\boxplus^{2}-\oplus^{2}-\boxtimes^{2}\] It would be clear your time must be \[\otimes\] But if you were allowed to continuously change to, \[\otimes^{2}+\boxplus^{2}-\oplus^{2}+\boxtimes^{2}\] now time would be \[\oplus\] ... After thinking about it for a while longer, I think you're right, @MigL. I think the mathematical reason has to do with the fact that the Lorentz group splits into 4 disconnected parts, \[L_{+}^{\uparrow},L_{+}^{\downarrow},L_{-}^{\uparrow},L_{-}^{\downarrow}\] Only one of them is a group, because it contains the identity transformation. The up-arrow ones are called orthochronous, and the + and - have to do with space orientation. The only one that can be continuously connected with the identity is the proper orthochronous. So I guess it can't be done. You can't reshuffle time and space, even if you preserve the metric signature. But it was fun. Edit: Although GR is different. You can move more freely with coordinate changes. I'd like to know what @Markus Hanke, @Mordred or other experts think about that.

OK. Point taken. But that's just another fiduciary or referential choice. I'm not convinced it's that essential, although it could have consequences. What I think Hanke is trying to say (maybe clumsily re-phrased by me) is illustrated with this parable: A very advanced ultra-dimensional civilization makes contact with us. They know we're inquisitive organisms and are very interested in our opinion on foundational questions about physical reality. They somehow develop a code to communicate with us (I'm leaving to them all the hard work). And they ask us: Hi, lot, what does the universe look like for you? Starting with: What dimensions do you see?" And we say, "well, it'll be difficult to explain what we see, but just for a start, we can see three spacial dimensions and one time dimension for describing change in this four-dimensional universe". Reply: "Mmmm. That's funny. We see one spacial dimension and three of what you call time dimensions" They exchange documentation in the form of theories, equations, experimental data, etc. And everything checks. It's only that what we call time, they call radius of a 3-dimensional time around the individual that's perceiving that time; and vice-versa. Who would be any the wiser about what they are calling time or space? The words "time" and "space" would just be arbitrary tags, mathematical dummies. I'm leaving the next idea for later.

I'm glad you mentioned time. We're still on-topic.

Good question. +1. I suppose modern psychometric techniques are getting us closer to it.

Maybe it's a British thing.

It does. I'm getting dizzy. We all want to have one foot on that group, I think. But, as Newton once said (or so they say he said), you become a prisoner of what you've said.

This may well be one of the most sensible things I've read today. Still, I'm not sure I'm ready for it.

John Wheeler was a great physicist, but not many people hold this view today. You should distinguish philosophical musings of physicists from robust physical principles. If you can't, I can't help you. Are you sure Wheeler said that? Let's see... Here's the quote, on page 28, not 27: https://books.google.es/books?hl=en&lr=&id=kF1INlvLSlkC&oi=fnd&pg=PA3&ots=UjrGJqkzFz&sig=B4jeCsHB510EWT5axFKitak_4S0&redir_esc=y#v=onepage&q&f=false That sounds to me more like a rhetorical question than the statement of a principle. And have you based your whole theory on a rhetorical question from John Wheeler? Rhetorical questions tend to be the weakest points in any argument. Anyway, my answer to that rhetorical question, and the answer from most scientists today is "no". There are other ways. So the quote is not "Observers are necessary to bring the Universe into being". (with capitals in "Universe"). The quote "as is" seems to come from Barrow&Tipler: http://www.dhushara.com/book/quantcos/anth/anth.htm Who apparently took a rhetorical question from Wheeler, made it into a "physical principle" and a few people out there went nuts with it. No serious science is made from this stuff. In any case, none of this has to do with the fact that you just copied and pasted standard equations from physics books to make your "paper" look like a genuine idea, as I pointed out. Neither Lorentz transformations, nor the geodesic equation, nor Einstein's equations derive from your idea. You just say the do.

Thank you all. I suppose it would take something really outrageous for me to use the report protocol. It's not me somehow. I even stopped giving people bad reputation points. I've noticed that the moderators on this site, after rational arguments have been presented, shift to shorter formulas to try and re-focus the conversation. You people spend a considerable effort and patience before someone is suspended or their post is closed. Those are good points. Ignoring other users should be a private, silent act. I'll try to remember that. But of course. That's very clever. Genuine disagreement, offering of arguments and counter-arguments, is very useful. I'm not as lucky as @swansont, who, in his own words, gets to play with "very expensive toys". My only laboratories are immediate reality and reason. Disagreeing with people in good faith is like a laboratory of sorts for me. I must confess I sometimes hold an opinion more strongly than my actual level of conviction is, just in order to see where my argument leads... That's part of the game. That's why we say "let me play devil's advocate here".

Sorry. I meant, obviously: (+1,-1,-1,-1). I hope I wasn't too confusing.

I've put three people on my ignore list in the last 48 hours. Am I a bad person? Could I have done otherwise? --> Possibility for a merging with Free Will discussion Am I missing the fun of discussing non-sense? Am I giving others more than their fair share of gibberish to deal with? Does this thread belong in Ethics?

Well put. +1

I was completely unaware of this. Thank you for opening that door into the weird for me. Sometimes I feel like I'm continually losing my innocence. I like to think that's a good thing. Here it is: I'm a little bit confused by the naught. But... Maybe Hanke was trying to make a further point that went over my head. I would rather say. Would a (-1,+1,+1,+1) universe be in any sense distinguishable from a (+1,-1,-1,-1), or a (-1,+1.-1,-1), etc.? Or signature-changing: (-1,+1,+1,+1) What makes the sign so special? And the particular parameter/coordinate that represents it? You can actually continually re-parametrize it and nobody would be any the wiser. This principle of indifference is whispering to our ear: Isn't there a fundamental decision about which coordinate in this continuum is the "selected" time for whatever characteristic determines what conscience is? And if so, which one is it? It must be one of them. And if not, if there is not a fundamental decision, what is it that makes the "special coordinate" so special in an inevitable way? A reshuffling of the basis entitles me in principle to decide that it's x that represents time in my mapping. x is x because I say so. x doesn't mean anything. It's just a mathematical tag. The mathematics speaks very clearly here. Invariance seems to suggest the opposite: There's nothing special about the time coordinate you pick, except it must be the only one with that sign in the metric. Looks appetising. Thank you.

I think @Markus Hanke has made an observation that is just pure genius. All of us, except @MigL have overlooked it. I'll bring it up to your attention ASAP and come back and try to take up the gauntlet he's thrown. Edit1: I'll bring it back to your attention. Maybe it was just me who wasn't paying attention. Edit2: Maybe it was just I. Dammit!! Very interesting. Now I understand much better, because you've brought this up before and I wasn't sure I completely understood.

Good points. +1. Let me add another one: There are more than two. Our mind tends to translate into binary if given the opportunity. Actually, there's a gradient of greys if you look at the picture closely enough. Our mind shapes what we see, and our mind likes to interpret the world in binary. Could that happen with time too? Our mind "likes" to shape the world as a continuous sequence?

Ok. You got your passageway. +1 We would have: A) The practical group: Why bother? B) The interested but not conviced: Mmmm, tell me more about it C) The 1st passageway: Goes from "why bother" to "tell me more about it" D) The puzzled or deeply concerned people: There's something special about time E) The 2nd passageway: Not convinced, but I have a funny feeling about time F) The unrestricted passageway: Goes from "why bother" to "there's something special about time" I'm selling out. <joke> You can add your own. For example: There's something spacial about being special </joke>

Well, I must tell you my choice of word, "hardliners" was not very fortunate. I should have written something like "practical". I would say you are practical, but then you seem to want to have a passageway to the stance "interested but not convinced". Is that any closer?