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You cannot have "perspective of photon". It's not a valid frame of reference precisely for the reasons you've stated. In particle physics, sometimes it's convenient to define light-front coordinates, but it only works because we take something that moves "almost" as fast as a photon as our reference frame. In these coordinates, some quantities become almost negligibly small, while others extremely large. Which allows to simplify computations. But it's precisely the fact that it's not actually light speed, and these quantities aren't exactly zero or actually infinite that allows us to carry out computations to begin with.

That's good news for everybody in the long run. Except some corrupt politicians in Russia, but that just makes it better for the rest of us.

And that's where I leave this conversation, because I have standards.

I have just explained three physical quantities we mean by time. Proper time is trivially measured. A clock measures its own proper time because its evolution is tied to time-parameter. The space-time coordinate time is measured by placing an object in the releavant rest frame and measuring its proper time. Again, clock works quite well. And statistical time is merely an ordering based on entropy, so you just need something that requires entropy increase to advance. Like a clock. So depending on which thing you mean by time, you measure it with clock, clock, or clock. Surprising, no? The problem with the oppinions, is that they are like butt holes. Education, on the other hand, seems to be a rare comodity.

Seriously? Option a) You produce just the waste heat + carbon. Option You produce same waste heat, but also reduce heating somewhere else. You also do not release carbon. You don't see how that's better? Chemicals used in solar panel production are a problem. But we are working on reducing this impact. Less than a decade ago, it took more energy to make a solar panel than it could produce in its life time, so solar panel use was just an export of carbon production. Modern solar panels produce 3-4 times as much energy as went into creating them. And this is rapidly improving. We can do way, way better with solar than just about any other energy source.

So the complication is that we actually say "time" and can mean several of related, but distinct concepts. 1) Time as a parameter in QM. We usually have proper time in mind when we talk about this one. 2) Time as a coordinate in Relativity. This one can be strictly defined in terms of differential geometry. 3) Time as casual ordering of events. This is the trickiest to define properly, and you have to drag entropy into it. And then you have various cross-disciplines. Relativistic Quantum Field Theory has to deal with both 1) and 2). Which gets really hairy. Statistical Mechanics deals with 1) and 3). There are only two realistic scenarios where you need to talk about all three. That's event horizon of a black hole and the Big Bang. If you have a good grasp of QCD, and Condensed Matter theory, you can have some idea of what's going on in such condition using mean field theory approximations. It's ugly, and our insight into exact physics of it is very limited to say the least. On the other hand, the precise QM of what's going at these kinds of places isn't really relevant to the discussion. So once we take what we know about space-time geometry of these places, we can talk about time there purely in terms of differential geometry. Ah, if it only weren't for the dark energy... Having a "South" pole in that analogy would imply a Big Crunch. Which isn't going to happen. I've only used spherical geometry as a most familiar illustration. The "North Pole" still behaves pretty much the same way. But there is no "South Pole". It just stretches out to infinity as far as we can tell. Which is very grim news. If universe is "infinite" in time span, and we happen to live in its first 14by, this Universe won't be habitable for very long.

That's simply because you don't understand what time is. Go take a course in differential geometry. When you're done, we can chat and I'll get into the mathematics of it all. Until then, North Pole analogy is the best you're going to get. If you want to keep insisting that it's wrong without understanding anything about space-time, well, that's a really stupid thing to do. I'm just going to leave it at that.

There is no such thing as "before" the big bang. Think of the big bang as the North Pole. The place from which you can only go South. What's North of North Pole? It's a bit of a silly question, isn't it? It's exactly the same way. The only time direction from Big Bang is forward. There is no such thing as time before Big Bang. Does that help?

Depends on what you need it for. GPS satellites take into account time dilation due to their orbital velocity and due to Earth's gravitational field. Did you know that there exists an orbit where time advances at exactly the same rate as on Earth's surface, because orbital time dilation equals the difference in gravitational time dilation due to different elevations? IIRC, GPS satellites are above that altitude, so their clocks run faster. In contrast, ISS is well bellow that altitude, and their clocks run slower. And when you need to be able to position your satellites just right, it's the sort of thing you have to keep in mind.

PB666, fair. But I'd be very skeptical about any long-range interactions as well. It's not the hell-freezing-over scenario like non-conservation of momentum would be, but I would still consider massive exhaust from the device to be far, far more likely. And hey, if this turns out to be just an ion drive using some leak/evaporation from the device, it'd still be pretty exciting. I just think detecting exhaust from that in a good vacuum chamber is going to be much easier than most other tests being suggested, and since it's still the most plausible scenario, I'd focus on looking for that. Now, if they can't find exhaust, then we need to run it through a whole bunch of tests to gather more data on how it behaves with all sorts of variables. Not to my knowledge. But there are Kickstarter TOS that would make it pretty much impossible. They require a working prototype of the final product. They've recently closed out a KS for a laser razor merely because their prototype had external laser source and a crappy fiber preventing it from operating at advertised efficiency. And that's for something that's absolutely rock-solid on paper. EMDrive will hit all these problems and more. There are some crowd-funding sites with laxer rules, but even they'd be skeptical about EMDrive, and rightly so. Personally, I have no problems with some research team trying to crowd-fund EMDrive research, but it needs to be super-transparent. Otherwise, we likely get the same problems you get with perpetual mobile type "research". And face it, whether EMDrive actually works or not, this is perfect ground for scam artists.

In a nut shell. I could write out formulas for what happens to time flow from perspective of accelerated observer on the rocket, but math gets hairy fast. If you haven't done any tensor calculus, it will be Greek to you. The simplest thing you can do is keep in mind that Special Relativity always works for any inertial observer. So any predictions you make from inertial frame will be valid without having to do complex math.

Heat capacity is 4.19 J/g for water in liquid state only. It's less for vapor. But yeah, regardless of whether that's the main effect or not, water vapor absolutely is a greenhouse gas. In fact one of the reasons CO2 doesn't have as big an impact as it could have is because across a wide band of IR atmosphere is already opaque due to all the water vapor.

Assuming reactionless is still irrational at this point. Even if it's completely new physics, which is unlikely enough, we still expect a reaction mass.

They know they aren't launching a hobby rocket from a parking lot, right?

There are a lot of contributing factors, but the main commonality is conservation of angular momentum. You know how figure scaters pull in arms to get themselves to spin faster? Same principle. The closer things are pulled together, the faster they turn. And as things collide, only one direction of rotation ends up winning out. So larger, older galaxies tend to be disk shaped. Same with protoplanetary disks that turn into planets around new stars. And around these planets, moons form turning in the same direction.

Doesn't have to. There is going to be self-interference, but this can result in a number of outcomes. Effect of time loops can actually be demonstrated with lasers quite elegantly, because a photon can be delocalized enough to interfere with itself along an earlier part of the beam. You can easily set up a grandfather paradox situation, for example and show that in QM it's trivially resolved without contradictions.

First of all, CTC is frame-independent. It's either a CTC in all frames, or it's not. There are precisely two properties of that curve. 1) It is closed. 2) It is time-like. Neither property changes with frame of reference. Second, it's not about "won't cause". It's about "can cause". Simplest way is to use a second wormhole. But you can also use that same wormhole twice after accelerating both mouths. So if that's where you're stuck, no, you don't have to time travel to go FTL. But if you can go FTL you inherently can time travel. If FTL is permitted, then so is time travel, because you can always come up with a trajectory that uses FTL to bring you back to where you started, exactly the same time and place. Which also means you can arrive at your departure point before you depart. Can. Don't have to. But you always can. And again, means of travel are irrelevant. You can use wormholes, warp drive, or pixie dust. It's a matter of space-time differential geometry only.

A lot of mistakes start with, "Even in Wikipedia you can read..." But yes, it's all about moving. Thing is, if you can create a wormhole between two points in a static frame, you can create it in a moving frame, because there is no difference between inertial frames. And then you get a wormhole with both ends moving, which is sufficient for time travel. Relativity is a very important concept in relativity. Who would have thought?

No. I have provided a scheme in which ship arrives on Earth before it left Earth. And as I have indicated, there is a general theorem that states that it is always possible if you can go FTL. There shouldn't be a discussion about it. If you don't understand Special Relativity, please, feel free to find a textbook to learn it. Otherwise, don't argue about things you don't understand. It's never a good idea.

Does not matter how many times you repeat the optical illusion counter, does not make it true. Please, learn some relativity, or stop arguing with people who have. Relativity of simultaneity is not an optical illusion and allows for actual violations of causality if you have FTL means.

Draw yourself a diagram of these events. It's seriously infuriating when people with zero formal education on relativity argue about these things. You don't understand my explanations? That's fine. But I'm also not going to waste my time reading a full lecture on special relativity that it will take for you to understand this. If you want to understand it, find a textbook. Read it. Understand it. I'll be happy to answer questions. FTL Capability = Time Travel. Again, it's a theorem in Special Relativity that carries over to General Relativity. I'm very sorry that you don't understand it, but your understanding does not change the physics.

Forget how warp works. You have ability to go from A to B faster than light. From perspective of moving observer, you arrive at B before you left A. You understand that, right? Ok, now before engaging warp, lets have warp ship accelerate to a high speed, so point of origin, A, is such a moving observer. You can still warp to B. And now you arrive at B before you left A from perspective of people left behind at A. Repeat the SAME thing at B to get back to A. Presto. You've arrived before you departed.

Causality is not the most important law of nature. It's not even a law of nature. It's a nice feature for some field theories. However, any field theory that supports gravity must also support causal loops, because thy are a feature of General Relativity. It's that simple. The fact that we rely on causality so much in our day-to-day lives means nothing to the rest of the universe.

Effective exhaust velocity. Yes. They are one and the same in metric.

Can't do that. To get gravity assist from Earth, you need a speed differential with Earth in Sun's orbit. The only practical way to do that is to get into a slightly elipitical orbit around the Sun that lets Earth catch up with you almost exactly a year later. That gives you enough of a boost to lower perhilion to bellow Venus' orbit, and aphelion to above Mars'. You then have an option to get a proper assist from Venus or Mars to go to wherever. Or, go for capture if these are your final destinations. Moon is a different matter. When you enter LTO from Earth, you are already on a highly eliptical orbit, so you get a great boost from the Moon. Sufficient to eject you from Earth's gravity all together. In fact, if you time everything just right, it's just enough to get you to the aforementioned Earth gravity assist maneuver, but you still have to spend a year in Sun's orbit do do that.