md65536

There *is* a physical change in measurements, but only per observer. The observed object doesn't change in any absolute way. You're trying to take the "relative" out of relativity, but then you end up with nonsense. A contracted length is contracted depending on the observer, it doesn't change the object in a universal way---because there is no such universal measurement in SR. There is no absolute time or distance. It is only a trivial illusion as much as all of time and distance is. But they are consistently measurable, so it is meaningless to call them illusions. You might as well say "reality isn't real". No, SR can describe what observers see, experience, observe, measure, and know from observation, even if you distinguish between those. Light doesn't have a frame of reference, so your "photon from the sun" example doesn't apply even with relative measurements. The Earth's speed relative to a photon is c for no time at all, over a distance that is contracted to zero length, so it doesn't make sense to speak of speeds relative to a photon. Imagining light experiencing things as instantaneous---strictly abstractly---doesn't change how we experience light, acting at a constant rate of c, using measurements that are relative to the particular measurer (observer).

Okay it's wonderful we all agree... but... but... As long as we all agree on what "experience" means. Here we're talking about effects that can be measured locally (an observer doesn't experience time dilation locally), and specifically we're excluding any observations of distant objects. If on the other hand you include observations as part of what you experience, then time dilation IS experienced, and yes you can experience multiple different amounts of time dilation relative to multiple differently moving objects: Each object's clock can be observed (ie. experienced) ticking at a different rate. In this way, time dilation is "experienced" in the observations of the moving objects as Doppler shifts in the rate of an observed clock's tick rate.* In SR, the observed Doppler shift is a combined effect of the moving clock actually (not illusory) ticking slow relative to you, and the appearance (can be considered illusory) of the clock ticking faster or slower due to a changing distance to the observed object, which means a changing travel time of incoming photons. elfmotat, I know you understand this better than I do, so this attempt at clarification is aimed at people like me who usually have misconceptions about something or other. * So... yes, a local clock's time dilation is not experienced except by other observers, but other clocks' time dilation is measured (experienced?) by the observer.

I think this part is misleading because it doesn't matter if the traveler and "stationary" observer have different momentum. It works out exactly the same if it's two twins in identical ships in space. It can work even if the first leg of a journey is symmetrical. An illusion would be if some observations were inconsistent with other observations. All observers measure a change in rate of moving clocks relative to local clocks, consistently as described by SR. Bring any two clocks together and all observers will agree on how the two times compare to each other. No one will think they observed incorrectly.

Uhhhh... okay well get researching! Battery powered flight adds yet another challenge. Gasoline has a higher energy density. Seriously, if you're going to do this you need to synthesize the state of the art in wing design, lightweight materials, etc... I want to defend your goals against people who say advancement is impossible, but I don't think any of the specifics of your ideas so far have been realistic. Eg. if you want to use batteries, look up what others have done with battery-powered flight.

I don't think success is impossible, but I don't think it's likely either. Many people have failed at trying to make flapping wings over a few hundred years probably. http://en.wikipedia.org/wiki/Ornithopter#Manned_flight Note the deaths and injuries... If you're serious about doing this I think you must do a lot of research into what's been done and succeeded, and what's failed. Expect years or decades of hard work to make incremental advancements over what's already done, realizing that the best that's been done so far was accomplished by teams with engineering and aeronautics expertise, which you'll need too. Personally I think that if you could have wings that were at all functional, their main function would be gliding. But there are gliding wings that also flap to provide thrust:

What does it even mean for gravity waves to not exist? Would that require that changes in a gravitational field are instantaneous? Wouldn't it require a whole bunch of new theories (scrapping all of GR and SR probably???) to model how that could even be possible?

More nanoseconds passed on Earth, but each of those nanosecond was shorter, relative to a nanosecond measured on the plane. --- err, on average that is, when you include relative simultaneity... Yes, both observers could potentially constantly observe the other's clocks. Both plane and ground observer see the same number N nanoseconds elapsed on the plane's clocks, and both observers see the same number N+51 nanoseconds elapsed on the ground clocks. Everyone agrees on any single clock, but different relatively moving clocks don't record the same elapsed time.

How do you know that aliens are about as massive as Americans and have a similar national energy output and are about as technologically advanced?

Edit: removed a misunderstanding of your analogy. Besides integration, you can also "neglect" acceleration time by making it happen during a time that you can ignore. Imagine the house is falling and you cut to a scene where the character is safely on the ground. What happens next doesn't depend on how the character escaped, by analogy. They don't disagree. Their measurements are different because they're measuring properties that are *relative*. They agree because the measurements are mutually consistent.

One additional thought: There are applications for using a traveler's clock and "rest" observer's distance to measure rate of movement: http://en.wikipedia.org/wiki/Proper_velocity#Applications However, even with this measure, you're not at all functionally faster than light. Yes, you can say that the traveler covered 7 LY while aging only 1 year, but light makes the same journey without aging at all. With this measure, light's rate of movement is infinite (or undefined I guess, to be precise). So to claim "faster than light" not only do you have to mix frames of reference, you also have to compare two very different measures of speed. ... You can be faster than c in measurements where c is not the rate of light, but then that's not faster than light.

Yes, but at least 7 years has elapsed on the destination object. It is functionally equivalent to having time slow for the traveler, though of course the traveler experiences time passing at a rate of 1s/s. Using the traveler's measuring devices he's traveled 1 LY in about 1 year. Using others devices he's traveled 7 LY in about 7 years. Mixing up frames of reference doesn't make a lot of sense. The traveler could say "No, I really did that in 1 year, and look I've only aged a year!" and it's true, but you've measured it taking 7 years... the traveler can't convince you otherwise. And the traveler has measured that 7 years has passed for everyone else. Functionally, relative to the planet and destination, it's taken 7 years. There are other measures of speed that are not limited by c, eg. rapidity and proper speed I think. You can use those if you want, but ordinary speed in SR is defined by measurements of distance and time from a common frame of reference. Science and science fiction often inspire each other. Often the idea behind some realistic sci fi is based on a scientific principle that may be decades old. Then, scientific imagining of how an idea might be implemented may borrow from the fictional imagining of it.

Isn't this essentially a "Theory of Anything", without a list of what's not possible? -- It could be used to predict anything you want, depending on the parameters you use. If so, how is a list of "reasons for something to not occur" any better than our current collection of theories and laws and assumptions? Neither is complete, right? So how could you ever complete the list of "reasons", to make this a true theory of everything? Or if not, are there any new specific predictions that this theory makes? For example, I could write "A Complete History of Earth" in one line: "Anything that has happened, has happened." And that's true of all of history, but gives no specific information that isn't in any other history book. Without the specifics, it's not useful.

I don't know if a better answer to this has already been given. I don't think "measuring disentanglement" at a particular time makes sense? You seem to be assuming that if a measurement at A is made, then there is an instantaneous change at B that is measurable at B, as if B can detect (ie "know") that A has made a measurement. That's not how it works. That would constitute a transfer of information. It should be simple to set up an experiment where each of A and B can be certain that each measures one of a pair of entangled particles "first" before the other. So there is no absolute "at the same time". There is no measurable information at either A or B in isolation that says what happened at the other, except when information from the two is combined by "normal" means (information transmitted at speeds <= c). I guess there's a paradox if you're stuck using classical intuition... what is described happening by A is not the same as what is described happening by B... BUT bring their information together and it will be consistent. I guess the description of what's "really" happening and the resolution to any paradox depends on a particular interpretation of QM.

That's true. Someone points out in the first "additional answers" link I posted that many of the examples aren't pseudoscience. Pseudoscience attempts to fake application of science, but very often the ones doing it don't realize they're doing it. They "don't know what it is that they don't know." Other times it is an intentional attempt to fake it, like with people who know the principles but find some reason to reject them (I'm thinking of climate deniers, or people who fight against science with alternative pseudoscience). However, I think that if someone presents incorrect facts, and falsely claims that science backs up their arguments, then they're probably faking it, even if they don't know they're faking it. If they try to apply principles and make a mistake, that's something else. Applying scientific principles incorrectly but assuming it's correct due to nothing but overconfidence in one's knowledge certainly fits your definition of pseudoscience, whether it's done by scientists or amateurs. Yes, getting science wrong isn't pseudoscience. But getting it wrong yet claiming it's right, while skipping over any attempt at scientific reasoning, or providing evidence or proof etc., must be?

One example is Erasto Mpemba http://en.wikipedia.org/wiki/Mpemba_effect who observed that hot water sometimes freezes faster than cold water. What's interesting is that I don't think he did anything pseudoscientific, but he was denounced by scientists who assumed the effect was impossible. This shows that there is not really a clear division between pseudoscientists and scientists, because either group can do things properly and either can do things wrong. "Real" scientists usually learn what they're doing with formal education, and are typically more familiar with how to spot and avoid pseudoscience. But I think that in any field of study one can get complacent and take some knowledge for granted, like in the example above:wrongly assuming that hot water must pass through the same state as cold water on its way to freezing, so must take longer. I think that anyone who got interested in science as a hobby or as amateurs, and then worked at it and studied and learned to do it right, may be included in your list. Science itself develops with the efforts of many over the years, so not all could have started off doing it right, if they themselves helped develop the right way to do it. Edit: Additional answers: http://ask.metafilter.com/167792/What-was-once-Pseudoscience-that-is-today-Accepted-Science http://chemwiki.ucdavis.edu/Analytical_Chemistry/Quantifying_Nature/The_Scientific_Method/Science_vs._Pseudo-science%3A_Limitations_of_the_Scientific_Method#From_Pseudo-Science_to_Science

I'm not sure what your point is. While airborne, wings support the body's weight, and the arms would not have to support any extra weight. While not airborne, supporting the weight of the wings at points on the ends of outstretched arms is extremely inefficient compared to other options. Either way, a support point on the back would be much more efficient. Supported at the back above the body's center of mass, with the body hanging free, the amount of extra effort to maintain posture in flight is equivalent to 0 lbs. While not in flight it could be similar to a backpack. Again, assuming the worst, stupidest design you can think of does not prove that it is impossible.

Why not remove the 10 lb weights from your wing design? You're missing my point. My point is that these are all SPECULATIONS, the latest being that there is no possible wing design that approaches a passive posture. Yet if a speculation falls on the side of the right answer, it is treated as fact, even if it is demonstrably false. These aren't scientific principles, they're challenges. You're answering why YOU would not be able to come up with a wing design, not why its impossible for someone else. In this case the challenge is that you'd have to deal with posture and balance, not that you'd need a specific minimum amount of effort to maintain a speculative "correct" posture.

So it's a problem of biology, not physics? How much effort is that?

Actually, early pedal-powered flights were done by women to minimize weight while still using high leg power. MIT's Daedalus "flew a distance of 71.5 mi (115.11 km) in 3 hours, 54 minutes"... a short while I guess. No extra flight muscles were attached. Right, sorry I got too attached to the "physically impossible" idea when it was never said. Still, a solution would simply side-step all of your example problems with a better design.

It's true, I'm over-zealously latching on to a small point of contention here. "It's a matter of physics" is the only point that I fully disagree with. I am arguing, because I don't like how if people explain the right answer with the wrong explanations, they think they're being scientific.

It would be more ignorant for someone to explain that it would be "physically impossible" to build one. So... "physically impossible" then? Also, if you had wings, you couldn't carry more than 2 pieces of luggage on a transatlantic flight without getting very tired. Therefore it is impractical physically impossible to fly. I ACCEPT that OP can't "grow" wings and fly around like a bird! But that's no excuse to pile on other silly reasons why the plan wouldn't work and pretend that it's a limitation of physics! There are real limits in physics, but "you need flight muscles" or "you need a nervous system in the wings" or "you might want to make more than a handful of flights" are not limitations that are due to physics, and could be worked around. Any engineering advancement could be considered science fiction before it's made. That doesn't mean it can't be done.

You're perhaps imagining a human flapping its wings like a bird and taking off vertically and flying around like a bird and saying "tweet tweet". I'm imagining a human attached to wings that are at the very least useful in some one specific circumstance. I'm thinking of the minimum that is at least physically possible, and then who knows what advancements can be made from there. You don't need extra power to take off. You can glide off a tree (there are animals that do) or a hill. I've already linked to proof that humans are physically capable of powering their own flight (http://en.wikipedia.org/wiki/Human-powered_aircraft). No "bodyweight!" or "oxygen!" arguments can disprove what's already been done. Right, and the reason that OP's request is impossible for the foreseeable future is biological (http://www.angryflower.com/breakf.gif), it's not a matter of physics. Physics is not restricted to the biological systems that exist today in nature. There are other ways to achieve winged flight, that are not physically identical to the way that birds fly. Yes, perhaps hang-gliding capabilities are not what OP's after, but I'm trying to think of a compromise that is physically possible, not make up false explanations for why it's impossible.

I don't mean to be so negative all the time, but why must everyone jump straight to the most problematic scenario and then treat it like it's the only way? It's not a lack of imagination, or a lack of logical thinking. I think that it must be a lack of critical problem-solving, or some kind of anti-problemsolving, where the goal isn't to come up with creative solutions, but rather build the biggest roadblocks. How many great achievements in science and engineering were dismissed as impossible by otherwise reasonable people, right up until someone with more drive and open-mindedness made it possible? - Wings do not need nerves. They can be "dead" tissue. - You do not need extra structural support for the ribcage. The wings could be very light (most are, whether natural or man-made). The body can be supported by its skin alone. It would take very little additional connection between wings and skin to either support the wings, or to have the wings support the body. - You don't need new layers of muscles if there is a way to use existing muscles to provide power. You don't need to fly like any particular animal does now, so you don't need to move the wings like a bird does, or a bee, so you don't need to be built like one. - Wings that are used for gliding only would require no new power, and would be at least "mildly functional". Altering your DNA to grow functional, powered wings is mad-scientist fiction, but it's entirely conceivable to create lightweight wings that could fold up to the size of a backpack, and could be surgically connected to metal piercings on the back, could be useful for gliding in favorable conditions, could be controlled by the arms for steering and perhaps some lift, and could accompany some other form of lift or propulsion maybe connected to the legs. That could be done now. Who knows what advancements could be made in a lifetime, if someone were serious about it, and studied engineering and incorporated ongoing advances in materials and aircraft design. All the "impossible because [some ridiculous made-up requirement]" just seems like attempts to shut down anyone who thinks way too far outside the box. OP's ideas are crazy and impractical, but that doesn't mean that there isn't a reasonable compromise.

That's simply false. http://en.wikipedia.org/wiki/Human-powered_aircraft Besides, your argument, taken literally, was disproved no later than over a century ago by the Wright brothers. Obviously it would take a lot to evolve or design biological wings to make human flight possible, let alone useful and efficient. You're probably right that it would be an evolutionary disadvantage. Any evolutionary mutations that could lead to wings and that may have happened in our past were not kept, so they probably offered no evolutionary advantage. Edit: Also, bigger than humans: http://en.wikipedia.org/wiki/Quetzalcoatlus

The defining feature of cranks is zealousness, as compared to eccentrics or crackpots. Zealousness leads to easy points to argue against, and all the subtle details in the pages of text end up being ignored. It's a shame, because everything is dismissed as a whole, whereas if the contentious points were simply dropped, the discussion could be about developing the details of the parts that are consistent with SR and GR. "The definitive guide to relativity" is probably not a reasonable goal here. A way of wrapping your head around relativity, for those who don't need to use it, is probably possible, as long as it's not misleading. New ways to interpret relativity, consistent with other ways, are probably also possible to develop.