Road rules3 mins ago
Why Can't We Travel Faster Than Light?
144 Answers
....because we are already travelling through spacetime at the speed of light, there is only one speed in spacetime.
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// As you speed up mass increases ... //This isn't true, although is a common misconceptio
14:59 Wed 01st Nov 2023
//
For a very very long time, scientists could not understand how a bee defied the known laws of aerodynamics - specifically, that based on the ration of its body weight to it's wing size, a bumble bee should not be able to fly - but clearly it did, regardless of what science said.
Developments in slo-mo photography revealed that the bee's wings are not fixed, and its rotating wing movement allows it to fly, proving that the previous fixed law of aerodynamics was not actually correct, given additional information. //
It doesn't say much for your argument that you rely on illustrating it with a wrong example. The initial (bumble)bee pape just had a calculation error. That was it. It wasn't a decades-long mystery -- pretty sure the original author noticed it himself, or at least was quick to accept the correction. The idea that bees defied scientific understanding is an urban myth, nothing more.
CTG said: //It's true, to be sure, that any scientific statement is subject to potential revision in future -- and, as a result, it's dangerous to say "never". But it's still a far more fatal flaw to completely misunderstand the problem. Faster-than-light travel isn't a matter of finding a cool new energy source. It's a matter of breaking all of our current theories -- and in a way that has to explain why this "wrong" theory has been so incredibly successful.// - that bit!
// Clare - // All of those can be overcome with patience and with enough will, and none of those run directly into a theoretical wall that can (almost surely) never be crossed. //
Thank you - my point exactly. //
Note that, to the extent that we agree, it applies to interstellar travel, not faster-than-light travel. As I made clear, it is a theoretical issue, not a practical one. Theories can change, but relativity is, in effect, now at the stage where it is not wrong, but incomplete.
// My argument is that, all the science minds agree that, at present, FTL travel is not scientifically possible.
But it may become so, in the future. //
This is one of those things that probably sounded like it was profound when you thought it, but is utterly empty of meaning when analysed at any level at all.
First of all: why may it become so? It's not enough to just point to other examples of change in science and say that there will be other changes in future. Of course that's true. Scientists know this. Every day they release papers in the thousands that say, in effect, that something we thought previously was wrong, or incomplete, or required another check. And those papers themselves are subject to further revisions tomorrow, and so on and on.
So, why this particular thing? That's a far more important question. What are the consequences, beyond allowing practical weekend jaunts in Andromeda in a few millennia? As it happens, scientists have already thought of it, and one meaningful theoretical issue is that our concept of causality would break down, since this turns out to be directly tied to the speed of light. Effects would be able to come before their causes, which defies all logic and reason. Now, maybe that's not a fatal flaw, but it's clearly an important issue to be able to fix if you're going to propose that c is no longer the maximal speed.
Secondly, was there anything that's suggested this to you other than "what if we're wrong, though?" Much as the bee example is a wild exaggeration, it says a lot about how little you understand the problem that you think it could even be analogous. Because, again, bee flight would be an engineering problem, not a theoretical one. After all, bees can fly. We can see this clearly. So anyone coming along and saying "that's impossible according to my calculations" is wrong from the outset. The evidence is already against them. Their theory would be wrong.
This situation is the complete reverse of the speed of light problem. This isn't just a prediction, it's an observation. We have seen nothing travel faster than light; predictions based on this assumption have turned out to be correct; and the theory itself is coherent. This last isn't necessarily persuasive, but, as a rule, the more convoluted (and therefore less elegant/coherent) a theory is, the less predictive power it has.
Put shortly, then: we have a good theory that, among other things, says that c is an absolute limit; and we have a huge volume of evidence in favour of this; and we have no evidence at all against it -- or, what hints there have been have failed themselves to withstand scrutiny.
TTT - // 16:12, well I hope Mr Hughes has taken on board some of that. We'll know next time the subject comes up I suppose. //
I have taken all of it on board, thank you Clare.
However, I remain unmoved from my original position - we can only know what we know now, and on the basis of what we know, we can make potential predicitions, with increasing sophistication and complexity as our knowledge increases.
But that does not mean that, at some time in the future, we may learn something that knocks all our current theories and predictions out of the ball park.
Simply because none of us know what the future holds.
I don't believe that simply because that statment is basic and not complex, that it must be any less true than any of the other posts and views offered.
We don't know what we don't know, and we don't know what the future is, or indeed what it is not.
I am sure no-one would argue with that - and that is the only point I have offered during the entire discussion.
Clare - // No, it doesn't mean that at all, as I am sure you well know :) //
I didn't - the perils of written communication.
// Only one of us is saying anything substantive, Andy, and it isn't the one who's making a nebulous appeal to the future. //
As far as i can see, your considerably detailed and obviously educated responses rely entirely on science as we know it now.
All I am saying is that none of us can know what the future holds.
I fail to see how anyone can argue against that.
"This isn't true, although is a common misconception. To be more precise, your kinetic energy increases. Mass stays the same throughout. No doubt E= mc^2 tricks people into thinking that if mass goes up then energy does, but that equation only holds when you are at rest; otherwise, the equation reads
E^2 - p^2c^2 = m^2 c^4
where p is momentum. It doesn't really matter how, but the whole point is that you energy and momentum change in a way that ensures that the m remains the same at all speeds.
None of which undermines the general point. E does grow towards infinity as your speed approaches c, and it's enough to argue that you'd therefore need infinite energy to reach, let alone exceed, the speed of light."
^^^I have an incredible amount of respect for people that understand things like this. My brain simply doesn't work that way so I didn't understand a bloody word of it - it may as well have been written in Swahili!.
Except you aren't making any point at all.
It's an admirable strategy, I'll grant you, but it's based on nothing - even, as I noted, the explicit examples you gave are entirely wrong, let alone irrelevant - and requires no understanding at all of the material in question. "What if you turn out to be wrong in future?" is always a possible question, and therefore is -- without justification -- always a vacuous question.
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