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Comment Re:I Want to Believe. (not) (Score 1) 312

I do believe I know the source of your misunderstanding, which is what I am attempting to address. The abstract concept of the infinite cannot be translated into the real world, you must be able to come up with a finite value for any practical application (or even an observation allowing one to test a theory.)

You are incorrect, that is not the source of my "misunderstanding", and I have explained why several times. Your discussion about arguments makes it sound like you want to be able to object to me without allowing me to object to you. Even if you were a Nobel laureate that would be preposterous (though in that case I would make my objections much more highly refined, for instance discussing them with a third party first).

You are attempting to derive a physical result from something that is unphysical.

The "unphysical" thing I'm discussing is a hypothetical newly discovered physical mechanism. I'm just arguing against that hypothetical discovery. I understand it has not been discovered yet, and my argument provides strong evidence that it will never be discovered. The general form of argument, "X is not physically observed so any argument Y that refers to X is fallacious", is itself flawed. It does not work eg. with the Pauli Exclusion Principle, where certain configurations of quantum particles are not observed and yet many solid arguments are based on the statistics that result.

The note that you are a mathematician is amusing to me, my girlfriend asked me what I was doing the other day, and my reply was "trying to convey a point to someone... probably a math student." If the student part is incorrect I apologize, but that comes from the constant arguments along the lines of "other guy is an idiot... who eats babies." This is not something you see often from those older than about 25, as it usually hurts your case more than helping it, and that is around the point by which most people will understand this.

You are correct. Especially in rereading my earlier points, my emotional tone very much hurt my case more than helping it--though I stand by the content of everything I said, the style I said it in was off-putting. I know I am correct in general, and I know that it does not come across that way, especially to the uninitiated, which most of the mods are. That explains why they chose you over me. In my view, you have not addressed my points (or understood many of them, I suppose?) while I have been able to understand and address all of yours to my satisfaction. I'm not sure what more to say. Good luck to you.

Comment Re:It's only 92% accurate ... (Score 1) 186

Yup, excellent point. I haven't actually seen statistics on how many people get infected that way, but it's of course a possibility. I remember reading an "advice to cheaters" guide that brought this up--it said that, if you're going to cheat, at *least* wear protection so the poor guy you're screwing over doesn't get sick.

Comment Re:It's only 92% accurate ... (Score 1) 186

I agree with all of your points. I do not agree that they were all actually relevant to my post (for instance, my 1-3 months remark was in the context of someone having bareback sex with multiple partners [note the "If you can't"'s], in which case it's perhaps even generous), but oh well. Actually, I do contest one point--"absolute certainty" about being HIV negative, while not 100%, can be extraordinarily close. One would need several tests after months of 0 risky behavior. I mostly meant to cover the case of eg. two pairs of married guys who want to bareback amongst themselves. And even then, my discussion completely ignores other STDs.

Comment Re:I Want to Believe. (not) (Score 1) 312

I feel I have listened to you but that you have not listened to me, since many of your points have been repeated in each post without you addressing my already-raised objections. I begin to suspect (just suspect) that you have some developmental problem like low-grade austism that prevents you from holding this debate properly. Still, I will raise my objections one more time.

You are assuming greater than infinite energy AND time travel to even put it forward as an argument...

No, I am not (and neither is my source). The misunderstanding is yours. I (and my source) made no assumptions whatsoever about how tachyons might form. As I said before maybe they've always existed, or maybe some change to special relativity won't alter the relativity of simultaneity in an essential way while also allowing the creation of tachyons from sub-light-speed matter.

As you approach the speed of light, energy input must approach infinity. To cross it requires a greater than infinite amount of energy. This is impossible, both in theory and practice.

I agree with you here, but yet again your statement is irrelevant. I do not care how one might create tachyons, I merely assumed their existence. I would like to remind you that my original FTL travel discussion was in the context of new discoveries allowing FTL communication, so the existence of a tachyon isn't even my own assumption, but rather my interpretation of someone else's probable argument. My original point was that FTL communication would result in such a radical violation of well-tested principles of special relativity as to be astonishing.

He was aware that infinite + 1 does not really exist, you are apparently not.

You have finally begun insulting me. I insulted you in my first reply and for that I apologize; I was too angered by the combination of your misconceptions and complete self-certainty. I was better in my second reply. I am actually a mathematician, so I probably know many more ways than you for "infinity + 1" to be interpreted reasonably. None of them are relevant here though.

Relativity therefore prohibits producing a tachyon.

Your argument merely shows the impossibility for relativity to produce a tachyon by accelerating a mass from sub-light speeds to FTL speeds. Barring just one method of production does not bar them all, and I've given two other methods above (twice now; you ignored them the first time so I've repeated them).

The theory prohibits this, and relativity has no appropriate application in an FTL scenario (this is WHY you get a causality violation.)

You have it backwards. You do not get a causality violation in an FTL special relativity scenario because relativity has "no appropriate application" there. Special relativity has "no appropriate application" to an FTL scenario because you get a causality violation (and most people want to keep causality). Your implication is backwards, and this is a fundamental error.

The observation in half of the relativistic light cone will be that effect preceded cause (the missile destroys the ship before it is launched.)

This doesn't make sense. A light cone is not a collection of frames of reference but rather the set of points in spacetime with zero interval from a given point. You probably meant to say that in "half" of all reference frames (specifically, those where the velocity along the line connecting the missle's start and end points is in the direction pointing from the start to the end point) the missile destroys the ship before it is launched.

So what happens?

1) Causality violation means that side B can fire their own FTL missile, destroy the ship on side A that launched the first one, and "undestroy" the one on side B by changing the past.

2) Causality remaining intact means that while side B can fire their own FTL missile and destroy the side A ship, the side B ship will remain destroyed, as this event has already happened.

Your argument is again backwards. You assume contradictions in both cases without realizing it--in case (1), causality violation is itself the contradiction, and it immediately leads to the paradox that ship B is both destroyed and not; in case (2), causality remaining intact contradicts the prediction of special relativity that causality is violated. Your contradictory and hopelessly vague discussion of "undestroy"ing a ship and one "remain[ing] destroyed" are artifacts of these backwards arguments.

The information on the cause is relativistic, the information on the effect is not. You cannot use relativity to determine cause and effect here, but cause still came before effect.

I cannot make this make any sense. I am essentially certain it is incoherent.

Unless you being responding to my actual points, I will not reply again.

Comment Re:It's only 92% accurate ... (Score 3, Informative) 186

you can go to the CDC website and see for yourself.

Indeed, here's a summary from the CDC from the end of last year. The most relevant part to your point:

While CDC estimates that only 4 percent of men in the United States are MSM, the rate of new HIV diagnoses among
MSM in the United States is more than 44 times that of other men (range: 522 – 989 per 100,000 MSM vs. 12 per
100,000 other men).

I have that link somewhat handy since I'm a gay male. For any other gay guys, to protect yourself...
1. Be monogamous; if you can't,
2. Skip anal and go for oral, which has a much smaller HIV transmission risk to both partners (basically 0 to the guy who's getting head); it's safest not to get cum in your mouth; if you can't,
3. Always use a condom and top--bottoming has a far higher transmission risk; if you can't,
4. Never fucking bareback with a guy you're not absolutely certain is HIV negative no matter what you asshole. You make us all look bad. If you can't,
5. Test yourself often (1-3 months). When you become positive, only have sex with other positive guys. There is no more "if you can't".

It should be noted that condom usage is highly effective but also imperfect. Depending on the study, they reduce exposure risk by only around 80%. For more precise transmission statistics, the Transmission section of the HIV/AIDS Wikipedia article has a good summary and good sources (though you usually need journal access to read them). The Prevention section is also worth reading.

Comment Re:I Want to Believe. (not) (Score 1) 312

You cannot use relativity to predict what would happen in an FTL scenario, because it is not possible within relativity. Not possible as in there is no way to do it, it does not exist. You are making a conclusion based on a theory which absolutely prohibits the scenario you are describing.

No. I gave a published reference for my view which uses special relativity to predict what would happen in an FTL communication scenario. You've given no such thing for yours, and this is the most important disagreement between us. I understand what the moderators see in your posts--you have many correct ideas, but you're wrong in numerous specifics.

You cannot get to the speed of light with a massive particle (never mind exceed it), and energy without mass cannot travel at any other speed (although you can affect the speed of light in a certain medium, so let me be clear that we mean "speed of light in a vacuum" as the limit.) The prediction of relativity is that FTL does not happen, not that time travel exists when it does.

That isn't even remotely the point. Certainly there is no known mechanism to get a massive particle past the speed of light, but I simply assumed a particle moving at that speed existed. Who knows, a priori maybe some particles would start out that way at the big bang, or "new physics" would allow for the infinite energy barrier to be overcome without seriously altering the rest of special relativity?

To restate it again (man is this horse dead) relativity says that tachyons do not exist. They are not an aspect of relativity, they are prohibited by it.

No! Relativity itself says no such thing. Relativity together with the assumptions that the universe is causal and consistent prohibit tachyons, as deduced in the book I referenced (and many, many other places).

If you assume a signal can arrive before it is sent, you can obviously violate causality. This is exactly what you are talking about with that argument, but the outcome is taken as a given before the argument...

You misconstrue my argument. It goes "Assume tachyons exist and special relativity is correct. From special relativity, derive time traveling communication. From time traveling communication, derive a paradoxical experimental result that violates causality. Since we also would like to assume causality works, tachyons must not exist or special relativity is incorrect. Since this part of special relativity has been heavily tested experimentally, most likely tachyons do not exist."

The clock synchronization statement is to get rid of the first scenario I listed, as I mean to assume that both clocks are stating the same thing. If they are in motion relative to each other you must account for this (such as we do with GPS.) It is easier to assume they are at rest with respect to one another (and does not detract from the argument to do so.) This lets us do away with relativity and use a Newtonian view of the universe with respect to the status of their clocks. I suppose I can clarify this further by saying two points three light hours away from each other, but also with no relative motion with respect to one another (or anything else that would cause time dilation for either observer with respect to the other, such as gravitational forces.) This leaves us with only the causality implications of the signal traveling faster than light (which is the discussion.) This signal does not need to allow a causality violation, as no matter how "fast" it gets there the signal will never be received before it is sent (even if the time on both clocks does not change between when it is sent and when it is received.)If a signal can transverse the three light hours in one second, you have FTL communication. You cannot however send the message, have the other party receive it, and send it back before it was sent. Causality would be intact, but relativity would not.

This gets at the heart of your misunderstanding. You've only given half the argument. The rest uses other reference frames in an essential manner (...as one would expect...). In rough terms (see the book I linked for more details, or consult any source that covers special relativity and causality), if FTL communication exists and causes two events to happen, there exists an inertial reference frame in which the relativity of simultaneity forces the effect to precede the cause. This is by definition a violation of causality--an observed event precedes its cause. One can leverage similar ideas to get time travel, but this is more direct in the present situation.

I will point out that while our world view changed when our understanding moved from Newtonian motion to relativistic motion, it does not mean that Newtonian motion is wildly inaccurate.

Yes, in a general sense. I had called your pseudo-Newtonian view "wildly inaccurate" in the present context, where the effects of the relativity of simultaneity are so crucial. Newtonian mechanics includes nothing like those effects.

Relativistic effects are outside newtons theories of motion and cannot be described within it, much like FTL is outside relativity.

One last time, you're the only one who says that.

our understanding of the physical laws of the universe is most certainly not complete.


Comment Re:Maybe quantum mechanics is too abstract (Score 1) 253

While that's true, try explaining memory management to your grandmother who's never touched a computer. That's basically the equivalent--it takes years to learn the math and physics used to describe any of this stuff, and that's for the most intelligent humans. Actually my example is probably too simple: memory management doesn't have that many big ideas in it, while fundamental physics has gobs of them. (It's hard to be quantitative here unfortunately.) Expecting a comprehensible explanation of the Higgs boson without tons of background might simply be expecting too much. (Humans seem to think that everything is possible, and it's just a matter of difficulty. Wrong. Some things are just impossible. Sorry.)

That said, a comprehensible explanation of quantum mechanics isn't nearly as rare as you seem to think. You might try Feynman's book, QED, for one version. It barely begins to cover the standard model, though, and by the end even Feynman was pretty clearly running out of good comprehensible explanations, but it starts very well.

Comment Re:Not the hardest one (Score 1) 179

Definitely, eh? Did you even read the first sentence of the summary?

'There's no straightforward way to define the difficulty level of a sudoku. I myself doubt if this is the hardest in the world, but definitely harder than my previous ones,' Inkala sets off humbly

[Yes, this completely contradicts the first link and the article title which both say this is the hardest Sudoku in the world. Terrible editing. Again.]

Comment Re:I Want to Believe. (not) (Score 0) 312

I'm sorry, but your discussion is largely incoherent and you have little to no idea what you're talking about. You should be down-modded.

Your example says absolutely nothing about violation of causality due to a change in the maximum speed at which information can propagate.

My example says that if one can produce particles that travel faster than the speed of light, then causality paradoxes arise. I said nothing about a "change in the maximum speed at which information can propagate".

You are either describing a situation in which there is improper time coordination, or you are assuming time travelling signals to start with.

That you even discuss "improper time coordination" suggests that you do not properly understand the relativity of simultaneity. My assumption was clear--the existence of tachyons, which are by definition particles that travel faster than light.

If something were to be discovered which could do this it would not necessarily violate causality, it would merely prove that relativity is either incorrect or incomplete

I don't know why you're repeating my conclusion back to me as if it's new. However, you underestimate the severity of the change. Special relativity would have to be wildly incorrect to make room for FTL particles. We're not talking about a minor change or a part of the theory that has some "room", like the small distance limit where quantum "sits".

Instant propagation of information would likely allow a universal clock across all space, and you could coordinate time by that.

Indeed, but this is completely irrelevant.

You would need to adjust for the faster travel time if you are synchronizing your clock based on the speed of light, but it would be trivial to do that anyway.

This makes no sense.

Under relativity it is undefined what would happen if you could travel faster than light, as the theory does not allow this. It is basically not usable in this case, and trying to do so would be foolish (it simply does not cover what you want to do, and you obviously have information that Einstein did not when he came up with it if you are communicating FTL.)

You have no idea what you're talking about. The theory of relativity makes predictions in this case. I have not found a single source (reputable or otherwise) that disagrees with me. The first relevant Google Books entry I found on the subject of course agrees with me--see section 11.1 for a derivation.

If I could send this post beyond the edge of the known universe and back with zero travel time I still cannot read it before it is written, and causality remains very much intact. The only thing that would change is that if you are three light hours away, I could get a message to you three hours before an electromagnetic signal would be capable of. We would be able to converse in real time instead of with the delay, nothing else.

You clearly have no understanding of the actual content of special relativity. You seem to be using a naive Newtonian view of the universe where it just happens that light travels at a maximum speed. This is wrong on many levels--how does one account for the fact that the speed of light is constant in all inertial reference frames, and that no inertial reference frame is privileged?

If you could produce the post I just wrote before I wrote it, you would have a causality violation. No rate of travel allows this, no matter how large it is.

Strictly speaking, you are correct in that no accepted, observed rate of travel allows causality violation. That is not at all your meaning, which is incorrect as noted above.

I am not sure why this is so hard for many people to understand.

Considering the numerous gaping holes in your own understanding, perhaps you should not consider it so difficult to see why grasping relativity is difficult for many people.

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Murphy's Law, that brash proletarian restatement of Godel's Theorem. -- Thomas Pynchon, "Gravity's Rainbow"