After all, the mathematician is taking it on faith that no right triangle exists in defiance of the Pythagorean Theorem
No, he isn't. He proves it strictly from the axioms of Euclidean geometry. And no, the axioms are not faith either, they are what defines the field. When doing non-Euclidean geometry, right triangles do violate the Pythagorean theorem.
I wonder if people using the term "deniers" will ever stop setting up strawman and accept that people are questioning the causes of climate change, not whether the climate actually changes. Someone can criticise AGW theories without also saying that the world is ever unchanging and will always be so.
There are both. However, as the evidence of climate change grows, more people move from "there is no global warming" to "OK, there may be global warming, but it's not man-made".
Of course you can mathematically embed spacetime into higher dimensional spaces, and then you may find a center of mass in those higher dimensional spaces. However, where that center of mass is will depend on how you embed spacetime into the higher dimensional space, and unless you can find any physical implications of that embedding which you can measure, it doesn't really make any sense anyway. Now, M theory does embed spacetime into higher dimensional spaces, with physical implications (gravitation can "leak" from our universe), so maybe one can define a meaningful center of mass of the universe there. But then, M theory by itself is still a purely speculative theory.
Another thing from II - Biff steals the time machine, alters the timeline, and returns to the regular 2015 to put the time machine back - Marty and Doc go back in time to the altered timeline, but when Marty suggests they just go back to 2015 to stop Biff Doc says they can't - Because they would simply travel along the altered timeline where Biff is now Rich
Then how the frick did Biff travel forward along the altered timeline to return the time machine?
Also, they leave Jennifer in one timeline, but get back in the other timeline to fetch her again. How did she manage to go from one timeline to the other?
Just as you have to pay the music industry tax on blank CD-ROMs you use to back up your own data, you also have to pay the book industry tax on photocopies of your own creations.
Do you know the terrible things which would have happened if he got laid at that time? Doc Brown knew that he had to prevent it, because he was coming from that future. Do you remember the terrible things about their children? No, that wasn't what happened in BTTF2. That was harmless, and Doc Brown could certainly have solved that by himself. The really terrible stuff was prevented by preventing Marty from getting laid at that day.
Is the center of mass of the universe constant, or does energy/matter conversion affect it?
No. There is no such thing as the center of mass of the universe, for the same reason as there is no place on earth that is the center of earth's surface.
5. Doc was happy where he was. He was fufilling a life-long dream. He was also terrified of the consequences of future time travel. The purpose of the letter was clear. He didn't want to enable Marty in coming back. He asked Marty not to come back.
Then why did he not destroy the time machine right away?
You could call paradox on the fact that Marty even remembers the "Clayton" name of the ravine after Doc saves her, since that would have made it so the name "Clayton Ravine" never would have existed for Marty to know about it
Well, inconsistencies propagate only slowly in the movie (e.g. Marty hindering his parents to meet doesn't make him disappear immediately), so surely he'll forget the old name only after some time.
In the begining of the third film Marty is at his highschool and he realizes the name has been changed.
The beginning of the third film doesn't start with Marty anywhere near his high school, nor was the high school named after a dead teacher; a ravine was named after the dead teacher.
Then Doc and Marty have a conversation about how Marty noticed already the highschool was renamed."
This conversation doesn't happen either.
What the hell movie did you watch?
The one before someone went back in time and fixed the most blatant plot holes.:-)
I didn't remember that. But then, there's still the possibility that he didn't want to return, or he expected to be able to get more Plutonium (or another source of energy) in the future (and indeed, the future had McFusion for him).
And of course, he might not have had enough Plutonium (the terrorists have given him just a certain amount), and didn't want to jump himself before he tested it at least with some living being. Now you want to argue that he did have enough Plutonium to jump into the future even after Marty used up the Plutonium for his jump into the past. But that was after he had learned what happened, and could plan for it (maybe he managed to use up less for his experiments).
Or maybe he had the additional Plutonium from the beginning, but there could be only enough Plutonium for two jumps in the car, and he would have refilled it before going into the future; however the terrorists killed him before he had the time to do so.
So what spacial trajectory does the time machine follow? Well, why would it not continue moving at 88mph deviation from the straight-line path through curved spacetime that it's already following - that being the same line being followed by the Earth?
Not exactly. The straight line path (also known of geodesic) is the path of a freely falling body (which will basically oscillate through earth; more exactly, it will be an [approximately] elliptic motion). Now normally you don't follow that path because the floor beyond you prevents you from doing so, but if the time machine follows the geodesic, it will inevitably end up inside earth (except if you happen to stop your journey at one of the times the trajectory has a turning point, and the rotating earth happens to not have moved a mountain or hill at that place).
The problem is that all geodesics starting at rest on the earth's surface go into the earth, and only occasionally leave it. Remember, the geodesics are the lines of free fall! Of course, you'd not end up in space. But if I had to choose between space and the inside of the earth, I think I'd choose space.
Well, they could just travel back along the spacetime geodetic currently tangential to their world line when the time travel starts. Which would almost certainly mean they'd end up somewhere inside earth:-)
Yet not smart enough to *require* enough plutonium in the chamber for a return trip.
There was no return trip planned, remember? All what was planned was a demonstration going one minute into the future. Obviously there was enough Plutonium for a second jump (probably a second demonstration was planned, probably with them inside). Marty's time jump into the past definitely wasn't planned.
That's like complaining about lack of forethought if someone jumps into someone else's car to flee (which is exactly what Marty did, BTW) and then it turns out there's not enough fuel in it.
The video evidence was clearly fake. True time travel would have created so much heat at departure that Doc Brown and Marty would have been fried. That's why real time machines are always inside buildings with heat shielding.
I don't even understand why this needs explanation. We all travel forward through time, and no-one needs an explanation of why we don't phase through the planet as time moves forward.
Of course we need an explanation. Fortunately we have it: Because the matter below us causes a force on us (combined gravitational, elastic and friction), keeping us at "the same" place relative to the ground. For the very same reason there's no problem with H. G. Wells' time machine, because it's at its place all the time (he constantly sees the surrounding, just in another pace; of course that sort of time travel has its own set of problems, but that's another story), so it also should be subject to this force. However the time machine in BTTF (as well as the time machines in most stories/movies/series today) basically makes a jump in time, i.e. it simply isn't there in the intermediate times, thus there's no force which would keep it in place.
Of course one could argue that since "the same place at another time" isn't exactly defined anyway, the inventor of the time machine must have built in some calculation of the relative position of earth at the destination, and manages to move the time machine to exactly that place. However, that should enable you to not only choose the time, but also the place where you appear (possibly restricted to the future/past light cone, but that covers all of the earth for any reasonable time travel; of course if you only travel a microsecond, your choices of reentry are severely limited). There's absolutely no reason then to restrict the time machine to enter at the "same" place.
Since 24" is exactly 5 times 4.8", the same resolution would even fit nicely for watching full HD movies (each movie pixel would cover exactly 5x5 screen pixels). You'd get a resolution of 9600x5400. Of course you'd have the problem that with 60Hz refresh rate and 3 bytes per pixel, you'd have to transfer about 70 gigabit per second to the screen...
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No, he isn't. He proves it strictly from the axioms of Euclidean geometry.
And no, the axioms are not faith either, they are what defines the field. When doing non-Euclidean geometry, right triangles do violate the Pythagorean theorem.
There are both. However, as the evidence of climate change grows, more people move from "there is no global warming" to "OK, there may be global warming, but it's not man-made".
... voltage over current
Of course you can mathematically embed spacetime into higher dimensional spaces, and then you may find a center of mass in those higher dimensional spaces. However, where that center of mass is will depend on how you embed spacetime into the higher dimensional space, and unless you can find any physical implications of that embedding which you can measure, it doesn't really make any sense anyway. Now, M theory does embed spacetime into higher dimensional spaces, with physical implications (gravitation can "leak" from our universe), so maybe one can define a meaningful center of mass of the universe there. But then, M theory by itself is still a purely speculative theory.
Also, they leave Jennifer in one timeline, but get back in the other timeline to fetch her again. How did she manage to go from one timeline to the other?
I've always wondered: why doesn't Biff meeting himself to give himself the almanac rip a hole in the space-time continuum?
Because the space-time continuum is stronger than you think.
Just as you have to pay the music industry tax on blank CD-ROMs you use to back up your own data, you also have to pay the book industry tax on photocopies of your own creations.
Do you know the terrible things which would have happened if he got laid at that time? Doc Brown knew that he had to prevent it, because he was coming from that future. Do you remember the terrible things about their children? No, that wasn't what happened in BTTF2. That was harmless, and Doc Brown could certainly have solved that by himself. The really terrible stuff was prevented by preventing Marty from getting laid at that day.
No. There is no such thing as the center of mass of the universe, for the same reason as there is no place on earth that is the center of earth's surface.
Well, of course you'd also move in time. But it would be much more useful if you could also say at which place you appeared in that time.
Then why did he not destroy the time machine right away?
Well, inconsistencies propagate only slowly in the movie (e.g. Marty hindering his parents to meet doesn't make him disappear immediately), so surely he'll forget the old name only after some time.
In the begining of the third film Marty is at his highschool and he realizes the name has been changed.
The beginning of the third film doesn't start with Marty anywhere near his high school, nor was the high school named after a dead teacher; a ravine was named after the dead teacher.
Then Doc and Marty have a conversation about how Marty noticed already the highschool was renamed."
This conversation doesn't happen either.
What the hell movie did you watch?
The one before someone went back in time and fixed the most blatant plot holes. :-)
Well, we know that: He entered the DeLorean after Doc Brown was apparently shot, and went into the past. The original Marty watched him doing that.
Repeat to yourself: It's just a show, I should really just relax.
So you say we won't get a MacFusion in five years?
I didn't remember that. But then, there's still the possibility that he didn't want to return, or he expected to be able to get more Plutonium (or another source of energy) in the future (and indeed, the future had McFusion for him).
And of course, he might not have had enough Plutonium (the terrorists have given him just a certain amount), and didn't want to jump himself before he tested it at least with some living being. Now you want to argue that he did have enough Plutonium to jump into the future even after Marty used up the Plutonium for his jump into the past. But that was after he had learned what happened, and could plan for it (maybe he managed to use up less for his experiments).
Or maybe he had the additional Plutonium from the beginning, but there could be only enough Plutonium for two jumps in the car, and he would have refilled it before going into the future; however the terrorists killed him before he had the time to do so.
Not exactly. The straight line path (also known of geodesic) is the path of a freely falling body (which will basically oscillate through earth; more exactly, it will be an [approximately] elliptic motion). Now normally you don't follow that path because the floor beyond you prevents you from doing so, but if the time machine follows the geodesic, it will inevitably end up inside earth (except if you happen to stop your journey at one of the times the trajectory has a turning point, and the rotating earth happens to not have moved a mountain or hill at that place).
The problem is that all geodesics starting at rest on the earth's surface go into the earth, and only occasionally leave it. Remember, the geodesics are the lines of free fall! Of course, you'd not end up in space. But if I had to choose between space and the inside of the earth, I think I'd choose space.
Well, they could just travel back along the spacetime geodetic currently tangential to their world line when the time travel starts. Which would almost certainly mean they'd end up somewhere inside earth :-)
But then, why does it only have a destination time setting, not also a destination place setting?
It isn't, cat is the opposite of split.
Yet not smart enough to *require* enough plutonium in the chamber for a return trip.
There was no return trip planned, remember? All what was planned was a demonstration going one minute into the future. Obviously there was enough Plutonium for a second jump (probably a second demonstration was planned, probably with them inside). Marty's time jump into the past definitely wasn't planned.
That's like complaining about lack of forethought if someone jumps into someone else's car to flee (which is exactly what Marty did, BTW) and then it turns out there's not enough fuel in it.
The video evidence was clearly fake. True time travel would have created so much heat at departure that Doc Brown and Marty would have been fried. That's why real time machines are always inside buildings with heat shielding.
Of course we need an explanation. Fortunately we have it: Because the matter below us causes a force on us (combined gravitational, elastic and friction), keeping us at "the same" place relative to the ground. For the very same reason there's no problem with H. G. Wells' time machine, because it's at its place all the time (he constantly sees the surrounding, just in another pace; of course that sort of time travel has its own set of problems, but that's another story), so it also should be subject to this force. However the time machine in BTTF (as well as the time machines in most stories/movies/series today) basically makes a jump in time, i.e. it simply isn't there in the intermediate times, thus there's no force which would keep it in place.
Of course one could argue that since "the same place at another time" isn't exactly defined anyway, the inventor of the time machine must have built in some calculation of the relative position of earth at the destination, and manages to move the time machine to exactly that place. However, that should enable you to not only choose the time, but also the place where you appear (possibly restricted to the future/past light cone, but that covers all of the earth for any reasonable time travel; of course if you only travel a microsecond, your choices of reentry are severely limited). There's absolutely no reason then to restrict the time machine to enter at the "same" place.
Since 24" is exactly 5 times 4.8", the same resolution would even fit nicely for watching full HD movies (each movie pixel would cover exactly 5x5 screen pixels). You'd get a resolution of 9600x5400. Of course you'd have the problem that with 60Hz refresh rate and 3 bytes per pixel, you'd have to transfer about 70 gigabit per second to the screen ...