Temporal mechanics for scifi readers
November 17, 2005 11:45 AM Subscribe
This is a question about temporal mechanics for scifi readers.
In the Dan Simmons novel Hyperion in the final chapter 'Remembering Siri', Merin Aspic is working on the construction of the farcaster portal in orbit around Maui-Covenant. It takes his ship five months of ftl travel time to get back to Hegemony space between contracts. For each ten-month round trip, on the planet's surface Siri ages 11 years. When they meet she is 16; at their 6th reunion she is 70 and he is 24.
Can you explain if this is possible? I read quite a bit of scifi and have a reasonable grasp on how temporal mechanics, at least in theory, are supposed to work. But I can't fathom this one. 10 months is 10 months. How does it end up being 11 years at one end? I guess I could just chalk it up to fiction and leave it be, but I wondered if there might be a more scientific (albeit theoretical) way of explaining it. Any ideas?
In the Dan Simmons novel Hyperion in the final chapter 'Remembering Siri', Merin Aspic is working on the construction of the farcaster portal in orbit around Maui-Covenant. It takes his ship five months of ftl travel time to get back to Hegemony space between contracts. For each ten-month round trip, on the planet's surface Siri ages 11 years. When they meet she is 16; at their 6th reunion she is 70 and he is 24.
Can you explain if this is possible? I read quite a bit of scifi and have a reasonable grasp on how temporal mechanics, at least in theory, are supposed to work. But I can't fathom this one. 10 months is 10 months. How does it end up being 11 years at one end? I guess I could just chalk it up to fiction and leave it be, but I wondered if there might be a more scientific (albeit theoretical) way of explaining it. Any ideas?
I think this can be explained with some non-fiction ideas. Assuming that the ship does indeed travel faster than light, he would age a whole lot slower. It's all pretty complicated physics, you can look up relativity on wikipedia to find out more. What happens is that since he is travelling faster than light, he only ages 10 months when everyone else (not travelling at this speed) age normally.
posted by EvilKenji at 11:52 AM on November 17, 2005
posted by EvilKenji at 11:52 AM on November 17, 2005
Forget faster-than-light. It's nothing to do with faster-than-light. Faster-than-light travel is probably not even possible.
As teece said, it's special relativity. All you have to do is travel very very fast (but still slower than light). The key idea is that a clock on a moving spaceship will tick slower relative to a clock that is standing still.
In other words, 10 months is not always 10 months. It depends whether you're moving or not.
posted by chrismear at 11:56 AM on November 17, 2005
As teece said, it's special relativity. All you have to do is travel very very fast (but still slower than light). The key idea is that a clock on a moving spaceship will tick slower relative to a clock that is standing still.
In other words, 10 months is not always 10 months. It depends whether you're moving or not.
posted by chrismear at 11:56 AM on November 17, 2005
This is just Simmons hand-waving. In his fictional universe FTL travel is 1) possible and 2) results in time dilation similar to that of traveling close to the speed of light. In the real universe, neither proposition is likely to be true. I believe that in theory, FTL travel should result in backward time travel (faster as you approach the speed of light from above it) such that Siri would actually be 10 years younger at each of Merin's visits.
posted by kindall at 11:56 AM on November 17, 2005
posted by kindall at 11:56 AM on November 17, 2005
Neat factoid: The clocks on the space shuttle are out of sync by a little bit when they return to earth, due to all that wacky relativity junk.
posted by blue_beetle at 11:59 AM on November 17, 2005
posted by blue_beetle at 11:59 AM on November 17, 2005
Another neat factoid: The clocks on GPS satellites adjust themsevles for any differences to clocks on earth due to time dilation effects.
I know faster than light speed is most likely not possible. This is of course science fiction; my only point was that since he's travelling freakin fast, he will age slower. This effect only really becomes a problem when you reach about 1/10 the speed of light.
posted by EvilKenji at 12:07 PM on November 17, 2005
I know faster than light speed is most likely not possible. This is of course science fiction; my only point was that since he's travelling freakin fast, he will age slower. This effect only really becomes a problem when you reach about 1/10 the speed of light.
posted by EvilKenji at 12:07 PM on November 17, 2005
Oh, I think kindall may be right. I haven't read Hyperion in years, but I was thinking the Hawking drive ships were sub-lightspeed, but indeed, Simmons made them FTL, I remember now.
So, the FTL part is fanciful, but the idea that 10 months could become 11 years is the accepted view of modern reality by physicist. You travel at Xc, where X is a number between 0 and 1 (in this case, probably something like .99999 or whatnot). You can do the math to figure out what value of X would be required to make 10 months at near-c become 11 years for another person not on the ship. With the reality of relativity, this can all get a bit confusing, as you can't just say "the guy in the space ship is going .9999c" and "the person at home is sitting still" because it as all relative, but the math is there. You just have to keep your frame of reference straight.
posted by teece at 12:16 PM on November 17, 2005
So, the FTL part is fanciful, but the idea that 10 months could become 11 years is the accepted view of modern reality by physicist. You travel at Xc, where X is a number between 0 and 1 (in this case, probably something like .99999 or whatnot). You can do the math to figure out what value of X would be required to make 10 months at near-c become 11 years for another person not on the ship. With the reality of relativity, this can all get a bit confusing, as you can't just say "the guy in the space ship is going .9999c" and "the person at home is sitting still" because it as all relative, but the math is there. You just have to keep your frame of reference straight.
posted by teece at 12:16 PM on November 17, 2005
just fyi...
the person on earth ages 132 months while the traveller ages 10 months? the factor by which time dilation occurs is 1/sqrt(1 - (v/c)^2), so 1-(v/c)^2 = (1/13.2)^2; (v/c)^2 = 1 - (1/13.2)^2; v = c sqrt(1 - (1/13.2)^2); v = 0.99713c
so if it were just "normal" slower than light travel it would imply a velocity of 99.713% the speed of light. that assumes infinite initial/turn-around/final acceleration, which would hurt a bit, so in fact top speed would be higher.
(maybe i've made a mistake, i was expecting a clued up author to have chosen something that came out as round numbers)
posted by andrew cooke at 12:21 PM on November 17, 2005
the person on earth ages 132 months while the traveller ages 10 months? the factor by which time dilation occurs is 1/sqrt(1 - (v/c)^2), so 1-(v/c)^2 = (1/13.2)^2; (v/c)^2 = 1 - (1/13.2)^2; v = c sqrt(1 - (1/13.2)^2); v = 0.99713c
so if it were just "normal" slower than light travel it would imply a velocity of 99.713% the speed of light. that assumes infinite initial/turn-around/final acceleration, which would hurt a bit, so in fact top speed would be higher.
(maybe i've made a mistake, i was expecting a clued up author to have chosen something that came out as round numbers)
posted by andrew cooke at 12:21 PM on November 17, 2005
ps just to extend teece's comment a bit, you may be thinking "if it's all relative, why doesn't she seem older to him, but him seem older to her?". which is a very good question. in fact the two people have different experiences - the man accelerates away, decelerates (sp?) to a stop, turns round 180 degrees, accelerates back, decelerates again to stop on earth.
in relativity, constant velocity is "relative" (it's not absolute - how fast you are going depends entirely on what you choose to measure things against), but acceleration most certainly is not. you "feel" acceleration (you don't feel velocity - imagine being in a fast moving aeroplane with te windows closed). so the two people have very different experiences, and the asymmetry (she is old, he is young) is not a problem.
posted by andrew cooke at 12:25 PM on November 17, 2005
in relativity, constant velocity is "relative" (it's not absolute - how fast you are going depends entirely on what you choose to measure things against), but acceleration most certainly is not. you "feel" acceleration (you don't feel velocity - imagine being in a fast moving aeroplane with te windows closed). so the two people have very different experiences, and the asymmetry (she is old, he is young) is not a problem.
posted by andrew cooke at 12:25 PM on November 17, 2005
I don't plan on reading the book, but if you plan on discussing the end of ANYTHING, it's a good idea to alert folks to [SPOILERS INSIDE]!
posted by mkultra at 12:50 PM on November 17, 2005
posted by mkultra at 12:50 PM on November 17, 2005
I read quite a bit of scifi and have a reasonable grasp on how temporal mechanics, at least in theory, are supposed to work.
What exactly is 'temporal mechanics' and how does it work?
posted by vacapinta at 12:58 PM on November 17, 2005
What exactly is 'temporal mechanics' and how does it work?
posted by vacapinta at 12:58 PM on November 17, 2005
Kindall is right. I don't think we really can say what happens when you travel FTL because we have no theoretical basis for it. The idea that time would run backwards is the one I've heard most often. But we shouldn't conflate sublight time dilation with whatever happens FTL.
The Forever War by Joe Haldeman is another good SF book, and mostly built around the twins paradox. And if you like that, you might like his book Forever Peace.
posted by adamrice at 1:22 PM on November 17, 2005
The Forever War by Joe Haldeman is another good SF book, and mostly built around the twins paradox. And if you like that, you might like his book Forever Peace.
posted by adamrice at 1:22 PM on November 17, 2005
'Temporal mechanics' is all that stuff about what happens if I go back in time and kill my grandad. Sci-fi philosophising, really. Wikipedia calls it an "area of quantum physics", which I think is a bit of a stretch.
posted by chrismear at 1:23 PM on November 17, 2005
posted by chrismear at 1:23 PM on November 17, 2005
Hmm, if he's actualy traveling faster then light under normal relativity laws, wouldn't he actualy get younger?
Anyway, in the real world the faster you go, the slower time is relative to things that are not moving as fast as you. Your mass also increases. As you approach the speed of light, time slows down infinitely and your mass approaches infinity.
However, you can not travel faster then light... are you sure that the character was actually traveling faster then light and not, say, 80% of the speed of light or something?
posted by delmoi at 1:32 PM on November 17, 2005
Anyway, in the real world the faster you go, the slower time is relative to things that are not moving as fast as you. Your mass also increases. As you approach the speed of light, time slows down infinitely and your mass approaches infinity.
However, you can not travel faster then light... are you sure that the character was actually traveling faster then light and not, say, 80% of the speed of light or something?
posted by delmoi at 1:32 PM on November 17, 2005
(maybe i've made a mistake, i was expecting a clued up author to have chosen something that came out as round numbers)
10 months is a round number :P
posted by delmoi at 1:36 PM on November 17, 2005
Faster-than-light travel is probably not even possible.
I'm pretty sure the same was once said of flying from city to city using huge metal winged tubes.
posted by weirdoactor at 1:48 PM on November 17, 2005
I'm pretty sure the same was once said of flying from city to city using huge metal winged tubes.
posted by weirdoactor at 1:48 PM on November 17, 2005
Let me understand this...the development of new technology does not use physics? Ever?
posted by weirdoactor at 1:57 PM on November 17, 2005
posted by weirdoactor at 1:57 PM on November 17, 2005
no, he's saying the limit was technological, not physical.
posted by andrew cooke at 1:58 PM on November 17, 2005
posted by andrew cooke at 1:58 PM on November 17, 2005
...and that wasn't what I said?
posted by weirdoactor at 2:05 PM on November 17, 2005
posted by weirdoactor at 2:05 PM on November 17, 2005
This has confused me too, actually. The classic example is that someone who goes to Alpha Centauri at nearly the speed of light will arrive in just a few months in 'local' time, while the full four years will pass on Earth.
It occurs to me that BOTH sides of the equation can be considered to be moving.... if it's valid to say that I'm headed for AC at nearly light speed, it's equally valid to say that both Earth and AC are going away from ME instead. So why does time slow down for me and not for them?
I still don't entirely grasp the concepts involved, but an explanation I saw said that the difference is that I, in the ship, am under acceleration. It's apparently the constant acceleration that makes the difference and causes one side to go slower.
Time slows down in a gravity well, and constant acceleration functions in exactly the same way, apparently.
But if that were the only part involved, you'd think that just accelerating real hard would immediately slow time down, without any light speed travel actually being required.
So I'm still confused. :)
posted by Malor at 2:07 PM on November 17, 2005
It occurs to me that BOTH sides of the equation can be considered to be moving.... if it's valid to say that I'm headed for AC at nearly light speed, it's equally valid to say that both Earth and AC are going away from ME instead. So why does time slow down for me and not for them?
I still don't entirely grasp the concepts involved, but an explanation I saw said that the difference is that I, in the ship, am under acceleration. It's apparently the constant acceleration that makes the difference and causes one side to go slower.
Time slows down in a gravity well, and constant acceleration functions in exactly the same way, apparently.
But if that were the only part involved, you'd think that just accelerating real hard would immediately slow time down, without any light speed travel actually being required.
So I'm still confused. :)
posted by Malor at 2:07 PM on November 17, 2005
wod: no.
posted by andrew cooke at 2:10 PM on November 17, 2005
posted by andrew cooke at 2:10 PM on November 17, 2005
if it's valid to say that I'm headed for AC at nearly light speed, it's equally valid to say that both Earth and AC are going away from ME instead.
Not symmetrical. The distance you have to travel, according to them, is the distance between Earth and AC (assume they are stationary wrt each other). The distance you have to travel, according to you, is a foreshortened distance since they are "moving"
posted by vacapinta at 2:18 PM on November 17, 2005
Not symmetrical. The distance you have to travel, according to them, is the distance between Earth and AC (assume they are stationary wrt each other). The distance you have to travel, according to you, is a foreshortened distance since they are "moving"
posted by vacapinta at 2:18 PM on November 17, 2005
I'll emphasize that the Hawking drive time-debt in the Hyperion books really has NOTHING to do with any physics. Basically, the years end up that way because that's how the author decided the ships should work.
posted by TheOnlyCoolTim at 2:22 PM on November 17, 2005
posted by TheOnlyCoolTim at 2:22 PM on November 17, 2005
Malor - it's one of those things that is a lot clearer once you do the maths, but:
a - you can only (easily) compare ages when two things are next to each and relatively stationary (so it's important that the man returns to earth before the comparison is made).
b - the change in the rate of flow of time depends on relative velocity, not acceleration. the explanation for the time dilation is intuitively obvious if you consider a clock that works by bouncing photons back + forth. see the diagram with red + green dots here. you don't need acceleration to explain it.
c - acceleration is important in the twins paradox because (1) it has to occur if you want to get the man back to the woman (see point (a)). and once you have acceleration then the two "lives" are not "the same", so there's no contradiction in one being older than the other. this is what makes your "both moving relative to each other" argument break down.
i don't claim to understand general relativity; you're right that gravity causes a similar effect, but i think it's a red herring here.
posted by andrew cooke at 2:24 PM on November 17, 2005
a - you can only (easily) compare ages when two things are next to each and relatively stationary (so it's important that the man returns to earth before the comparison is made).
b - the change in the rate of flow of time depends on relative velocity, not acceleration. the explanation for the time dilation is intuitively obvious if you consider a clock that works by bouncing photons back + forth. see the diagram with red + green dots here. you don't need acceleration to explain it.
c - acceleration is important in the twins paradox because (1) it has to occur if you want to get the man back to the woman (see point (a)). and once you have acceleration then the two "lives" are not "the same", so there's no contradiction in one being older than the other. this is what makes your "both moving relative to each other" argument break down.
i don't claim to understand general relativity; you're right that gravity causes a similar effect, but i think it's a red herring here.
posted by andrew cooke at 2:24 PM on November 17, 2005
Response by poster: mkultra: Don't worry, no spoilers. It's just a detail of the story, hence no warning. I do recommend the book though.
vacapinta: By 'temporal mechanics', which is a fairly prevalent term in the Star Trek universe, I'm referring to stuff which has an effect on an observer's timeline. On review, what chrismear said. It really is more fiction than anything, at least for now. Anyway, after reading some of the blindingly intelligent responses to the question, I think I've concluded I don't understand it that well after all.
posted by BorgLove at 2:24 PM on November 17, 2005
vacapinta: By 'temporal mechanics', which is a fairly prevalent term in the Star Trek universe, I'm referring to stuff which has an effect on an observer's timeline. On review, what chrismear said. It really is more fiction than anything, at least for now. Anyway, after reading some of the blindingly intelligent responses to the question, I think I've concluded I don't understand it that well after all.
posted by BorgLove at 2:24 PM on November 17, 2005
Malor, your interpretation makes sense to me. It explains the Air Jordan effect -- he jumps with such an acceleration that time slows down around him, making him look like he's flying. Also it would explain how time seems to stand still right as you jump off a high ledge -- time is slowing down as you accelerate!
I'm just kidding. I think it's difficult for us to generate accelerations that cause noticeable time slowdowns.
Also: I think the space shuttle time-sync mismatch mostly comes from the fact that they're slightly farther out of Earth's gravity well, not from their speed or acceleration.
posted by breath at 2:29 PM on November 17, 2005
I'm just kidding. I think it's difficult for us to generate accelerations that cause noticeable time slowdowns.
Also: I think the space shuttle time-sync mismatch mostly comes from the fact that they're slightly farther out of Earth's gravity well, not from their speed or acceleration.
posted by breath at 2:29 PM on November 17, 2005
Time slows down in a gravity well, and constant acceleration functions in exactly the same way, apparently.
Yes. the whole thing can be re-phrased in GR
But if that were the only part involved, you'd think that just accelerating real hard would immediately slow time down, without any light speed travel actually being required.
It does. But acceleration implies velocity no?
posted by vacapinta at 2:34 PM on November 17, 2005
Yes. the whole thing can be re-phrased in GR
But if that were the only part involved, you'd think that just accelerating real hard would immediately slow time down, without any light speed travel actually being required.
It does. But acceleration implies velocity no?
posted by vacapinta at 2:34 PM on November 17, 2005
Malor, one concept that can be useful in sorting out these relativity troubles is proper time. For a given time interval ∆t0, an observer in a fixed reference frame with respect to the occurrence used to measure ∆t0 will measure the shortest possible time for that occurrence. It's sometimes easier to think about proper time.
But the problem with the twin paradox is much simpler than it seems (and subtle and often misunderstood): the theory of special relativity is only valid in an inertial reference frame (an inertial reference frame is one at rest or moving with a constant velocity -- no acceleration). The twin that stays behind on earth as his brother goes to Alpha Centauri is in an inertial reference frame (or damn close -- the Earth does not accelerate much). The twin going to Alpha Centauri has to accelerate up to near c, decelerate to a stop, and then accelerate back up to c, and then decelerate again upon arriving home. Thus, there are periods of time when one no inertial reference frame can be found between the two twins, so their motion is not entirely relative.
So you're confusing two issues, I think. The speed near c accounts for the time dilation, but the acceleration accounts for the lack of complete relativity between twins. Thus there is no paradox.
You have to move on to general relativity to start to play with non-inertial reference frames, and the math there is much [much!] more complicated.
posted by teece at 2:36 PM on November 17, 2005
But the problem with the twin paradox is much simpler than it seems (and subtle and often misunderstood): the theory of special relativity is only valid in an inertial reference frame (an inertial reference frame is one at rest or moving with a constant velocity -- no acceleration). The twin that stays behind on earth as his brother goes to Alpha Centauri is in an inertial reference frame (or damn close -- the Earth does not accelerate much). The twin going to Alpha Centauri has to accelerate up to near c, decelerate to a stop, and then accelerate back up to c, and then decelerate again upon arriving home. Thus, there are periods of time when one no inertial reference frame can be found between the two twins, so their motion is not entirely relative.
So you're confusing two issues, I think. The speed near c accounts for the time dilation, but the acceleration accounts for the lack of complete relativity between twins. Thus there is no paradox.
You have to move on to general relativity to start to play with non-inertial reference frames, and the math there is much [much!] more complicated.
posted by teece at 2:36 PM on November 17, 2005
There's nothing invalid about applying special relativity to acclerating frames -- the maths just gets a bit trickier.
posted by chrismear at 2:41 PM on November 17, 2005
posted by chrismear at 2:41 PM on November 17, 2005
I think the space shuttle time-sync mismatch mostly comes from the fact that they're slightly farther out of Earth's gravity well, not from their speed or acceleration.
As you increase your distance from the earth's mass, the effect of general relativity is to speed up your internal clock. The shuttle's clock runs slow compared to clocks on the earth. So the overwhelming effect here is special relativity slowing down the shuttle's clock because they're simply moving faster than us down on earth.
posted by chrismear at 2:52 PM on November 17, 2005
As you increase your distance from the earth's mass, the effect of general relativity is to speed up your internal clock. The shuttle's clock runs slow compared to clocks on the earth. So the overwhelming effect here is special relativity slowing down the shuttle's clock because they're simply moving faster than us down on earth.
posted by chrismear at 2:52 PM on November 17, 2005
There's nothing invalid about applying special relativity to acclerating frames -- the maths just gets a bit trickier.
That seems like a semantic trick to me, chrismear, unless I am misunderstanding you.
Special relativity provides a couple of axioms that can be applied to the natural world. From those axioms we get some algebra. Those axioms postulate that they are to be applied with respect to an inertial reference frame. So, by definition, special relativity doesn't apply under acceleration.
Yes, similar ideas to those espoused in special relativity can be applied to non-inertial frames, but that is general relativity and a whole new set of math.
Am I confused? I'm sure vacapinta could straighten us out, as if I remember correctly he/she is an astrophysicist or such.
posted by teece at 2:57 PM on November 17, 2005
That seems like a semantic trick to me, chrismear, unless I am misunderstanding you.
Special relativity provides a couple of axioms that can be applied to the natural world. From those axioms we get some algebra. Those axioms postulate that they are to be applied with respect to an inertial reference frame. So, by definition, special relativity doesn't apply under acceleration.
Yes, similar ideas to those espoused in special relativity can be applied to non-inertial frames, but that is general relativity and a whole new set of math.
Am I confused? I'm sure vacapinta could straighten us out, as if I remember correctly he/she is an astrophysicist or such.
posted by teece at 2:57 PM on November 17, 2005
No semantic trick intended. The fundamental physical principles of SR still apply when things start accelerating. And the fundamental principles of SR in no way specify that they apply to constant velocity situations only.
The only thing that you're getting wrong by not bringing in GR is that you're ignoring gravitational effects.
posted by chrismear at 3:10 PM on November 17, 2005
The only thing that you're getting wrong by not bringing in GR is that you're ignoring gravitational effects.
posted by chrismear at 3:10 PM on November 17, 2005
I'm no astrophysicist but I agree with teece on this one, not chrismear. SR requires an inertial reference frame. So the paradox can still be worked out by invoking the frame of the person who stays behind. Then the problem becomes working out path lengths of proper time.
If you're going to try to make sense of things from an accelerating frame, you need GR. In GR, gravity and acceleration are essentially equivalent so I'm not sure whats meant by "The only thing that you're getting wrong by not bringing in GR is that you're ignoring gravitational effects." because if you ignore gravity/acceleration you're ignoring the problem altogether.
posted by vacapinta at 3:20 PM on November 17, 2005
If you're going to try to make sense of things from an accelerating frame, you need GR. In GR, gravity and acceleration are essentially equivalent so I'm not sure whats meant by "The only thing that you're getting wrong by not bringing in GR is that you're ignoring gravitational effects." because if you ignore gravity/acceleration you're ignoring the problem altogether.
posted by vacapinta at 3:20 PM on November 17, 2005
I believe that in theory, FTL travel should result in backward time travel (faster as you approach the speed of light from above it) such that Siri would actually be 10 years younger at each of Merin's visits.
No, actually, that'd be nice. The Lorenz-Fitzgeraled equations require you to take the square root of a negative number when the velocities involved exceed c; if I recall correctly, the term (c^2 - v^2)^(1/2) appears in a denominator somewhere. This leaves you with having to add "imaginary time" to a person's age. When v = c, the denominator equals zero, which leaves you with an indeterminate result.
Indeterminate and imaginary results for equations meant to describe scalars such as time interval and measured length tend to suggest that the equations do not apply under those conditions. In other words, the idea that the value of a time interval could have an imaginary term or could have more than one value is generally thought to be meaningless.
posted by ikkyu2 at 4:06 PM on November 17, 2005
No, actually, that'd be nice. The Lorenz-Fitzgeraled equations require you to take the square root of a negative number when the velocities involved exceed c; if I recall correctly, the term (c^2 - v^2)^(1/2) appears in a denominator somewhere. This leaves you with having to add "imaginary time" to a person's age. When v = c, the denominator equals zero, which leaves you with an indeterminate result.
Indeterminate and imaginary results for equations meant to describe scalars such as time interval and measured length tend to suggest that the equations do not apply under those conditions. In other words, the idea that the value of a time interval could have an imaginary term or could have more than one value is generally thought to be meaningless.
posted by ikkyu2 at 4:06 PM on November 17, 2005
I'm sorry if I wasn't clear, but I'm not just waving my hands around here. I've done the calculations for accelerating particles using just the principles of SR, and they give you good answers -- as long as you're working in a local context where any gravitational effects are small enough to be ignored.
It's a similar principle to doing Newtonian mechanics of billiard balls without worrying about the Newtonian gravitation between the balls.
(That's not a perfect analogy, because Newtonian graviation doesn't include Newtonian mechanics in the way that GR includes SR, but the idea of ignoring negligable effects is valid.)
In SR, once you've defined displacement as a 4-vector in spacetime, you can define the 4-velocity as the derivative of the 4-displacement with respect to proper time. This formulation gives you all the standard results that you're used to for constant velocity problems.
You can then write down the 4-acceleration as the derivative of the 4-velocity with respect to proper time. And it works fine. The 'physical' acceleration of the particle (i.e. its proper acceleration, which can only consistently defined as its acceleration as measured in its own instantaneous rest frame) can be found from the 4-acceleration quite straightforwardly (you take the scalar product of the 4-acceleration with itself, and you get -a2, where a is the proper acceleration).
It's all self-consistent, and valid within its field of applicability. SR doesn't blow up or anything when you introduce accelerated particles.
posted by chrismear at 5:06 PM on November 17, 2005
It's a similar principle to doing Newtonian mechanics of billiard balls without worrying about the Newtonian gravitation between the balls.
(That's not a perfect analogy, because Newtonian graviation doesn't include Newtonian mechanics in the way that GR includes SR, but the idea of ignoring negligable effects is valid.)
In SR, once you've defined displacement as a 4-vector in spacetime, you can define the 4-velocity as the derivative of the 4-displacement with respect to proper time. This formulation gives you all the standard results that you're used to for constant velocity problems.
You can then write down the 4-acceleration as the derivative of the 4-velocity with respect to proper time. And it works fine. The 'physical' acceleration of the particle (i.e. its proper acceleration, which can only consistently defined as its acceleration as measured in its own instantaneous rest frame) can be found from the 4-acceleration quite straightforwardly (you take the scalar product of the 4-acceleration with itself, and you get -a2, where a is the proper acceleration).
It's all self-consistent, and valid within its field of applicability. SR doesn't blow up or anything when you introduce accelerated particles.
posted by chrismear at 5:06 PM on November 17, 2005
Carl Sagan can explain it to you.
For the best illustration of the twin paradox, and for a great classic sf novel, check out Heinlein's "Time for the Stars" (one of his juveniles), which has perfect science except for, you know, the whole telepathy thing. Shockingly, it's out of print, but seems to be available used.
posted by booksandlibretti at 6:18 PM on November 17, 2005
For the best illustration of the twin paradox, and for a great classic sf novel, check out Heinlein's "Time for the Stars" (one of his juveniles), which has perfect science except for, you know, the whole telepathy thing. Shockingly, it's out of print, but seems to be available used.
posted by booksandlibretti at 6:18 PM on November 17, 2005
I've always found Einstein's original train + mirrors daydream the easiest way to understand the time dilation argument of special relativity.
Assume the postulate that the speed of light in a vacuum is a constant, fixed, maximal value.
Get a friend in a transparent train to rig up a lightbox thingy, with a light pulse travelling up and down vertically. Kind of like the old Pong game. Imagine that the speed of light is slow enough that you can see it. You both have an identical "light clock".
Now, when both of you at rest standing in front of each other there is little problem accepting that what you see is what you get: the light bounces up and down at a steady rate.
Now imagine you stand still while your friend gets in a train that runs perpendicular to your path. It's pretty far away but you can see the light pulse clearly. Now imagine that the train begins travelling back and forth in front of you, faster and faster. For the sake of simplicity, say that it stops accelerating during its passing when you are observing it.
Within the train, your friend notices nothing different. The light continues to bounce up and down, regular as clockwork.
You observe the train and yes, the light continues to bounce up and down.But consider this, if the train is now travelling at, say, 50% of the speed of light, then for the light pulse to bounce off one mirror and reach the other mirror, it must travel a longer "distance" relative to you. It's a kind of diagonal path when you are looking at it.
But the speed of light is fixed. And "time" is measured here by the distance divided by the speed of light. Which is constant. Therefore, because the distance is increasing (from your perspective), the rate of the passing of time on the train appears to you to be slowing.
Were you able to see this visually, it would sppear that the light pulses on the train were s-l-o-w-i-n-g down relative to your own light pulses. And they would get slower the faster the train went.
The key thing to understand the difference in relative rates is that you stayed put while your friend was accelerated away from you and then towards you at the end to compare results. There are three "inertial" frames (that is, local areas in which time passes similarly and consistently) working in the scenario, and while you occupy one, your friend on the train has to transition between two of them, and it's during this transition that the paradox of different time elapse occurs.
There are other physical and mathematical metaphors for looking at the twin paradox, but I like this little Java applet that shows you the "light cones", or the constrained regions of visibility that would occur within spaceships travelling near the speed of light under SR.
posted by meehawl at 6:28 PM on November 17, 2005
Assume the postulate that the speed of light in a vacuum is a constant, fixed, maximal value.
Get a friend in a transparent train to rig up a lightbox thingy, with a light pulse travelling up and down vertically. Kind of like the old Pong game. Imagine that the speed of light is slow enough that you can see it. You both have an identical "light clock".
Now, when both of you at rest standing in front of each other there is little problem accepting that what you see is what you get: the light bounces up and down at a steady rate.
Now imagine you stand still while your friend gets in a train that runs perpendicular to your path. It's pretty far away but you can see the light pulse clearly. Now imagine that the train begins travelling back and forth in front of you, faster and faster. For the sake of simplicity, say that it stops accelerating during its passing when you are observing it.
Within the train, your friend notices nothing different. The light continues to bounce up and down, regular as clockwork.
You observe the train and yes, the light continues to bounce up and down.But consider this, if the train is now travelling at, say, 50% of the speed of light, then for the light pulse to bounce off one mirror and reach the other mirror, it must travel a longer "distance" relative to you. It's a kind of diagonal path when you are looking at it.
But the speed of light is fixed. And "time" is measured here by the distance divided by the speed of light. Which is constant. Therefore, because the distance is increasing (from your perspective), the rate of the passing of time on the train appears to you to be slowing.
Were you able to see this visually, it would sppear that the light pulses on the train were s-l-o-w-i-n-g down relative to your own light pulses. And they would get slower the faster the train went.
The key thing to understand the difference in relative rates is that you stayed put while your friend was accelerated away from you and then towards you at the end to compare results. There are three "inertial" frames (that is, local areas in which time passes similarly and consistently) working in the scenario, and while you occupy one, your friend on the train has to transition between two of them, and it's during this transition that the paradox of different time elapse occurs.
There are other physical and mathematical metaphors for looking at the twin paradox, but I like this little Java applet that shows you the "light cones", or the constrained regions of visibility that would occur within spaceships travelling near the speed of light under SR.
posted by meehawl at 6:28 PM on November 17, 2005
Malor: It occurs to me that BOTH sides of the equation can be considered to be moving.... if it's valid to say that I'm headed for AC at nearly light speed, it's equally valid to say that both Earth and AC are going away from ME instead. So why does time slow down for me and not for them?
One of the weirdest things about special relativity is that you can have two apparently inconsistent interpretations of a set of physical events, and yet both of those interpretations are equally valid.
You're completely right -- in the situation you describe, the physical setup is exactly symmetrical, and there are two valid interpretations.
If you're sitting on the spaceship, you can decide to interpret things as if the Earth is still, and you are zooming along at high speed. In that case, you know that your internal clock is ticking slower relative to the people on Earth. They are aging faster than you.
Or, you could turn it around. You could decide that, no, I'm actually stationary, and that planet just zoomed past me at near-light speed. In that case, their internal clocks must be ticking slower than mine. I'm getting older fast than them!
Now, these conclusions appear to be contradictory. But both of these interpretations are completely valid. It sounds ridiculous, but it's true. Now, how can that be possible? Surely you could just send a message, ask how old they are, and check which interpretation was 'true'?
Well, yes, you could send a message. But that message must cross the now vast distance between you and the Earth. And any reply they send must travel that distance too.
To make any sense of the results, you know that you have to correct for that transmission time. And here's the key. The way you correct for the transmission time depends on your initial interpretation of the physical setup. Whatever you do, as long as you remain consistent in your interpretation, you'll get a result that makes perfect, logical sense.
posted by chrismear at 6:38 PM on November 17, 2005
One of the weirdest things about special relativity is that you can have two apparently inconsistent interpretations of a set of physical events, and yet both of those interpretations are equally valid.
You're completely right -- in the situation you describe, the physical setup is exactly symmetrical, and there are two valid interpretations.
If you're sitting on the spaceship, you can decide to interpret things as if the Earth is still, and you are zooming along at high speed. In that case, you know that your internal clock is ticking slower relative to the people on Earth. They are aging faster than you.
Or, you could turn it around. You could decide that, no, I'm actually stationary, and that planet just zoomed past me at near-light speed. In that case, their internal clocks must be ticking slower than mine. I'm getting older fast than them!
Now, these conclusions appear to be contradictory. But both of these interpretations are completely valid. It sounds ridiculous, but it's true. Now, how can that be possible? Surely you could just send a message, ask how old they are, and check which interpretation was 'true'?
Well, yes, you could send a message. But that message must cross the now vast distance between you and the Earth. And any reply they send must travel that distance too.
To make any sense of the results, you know that you have to correct for that transmission time. And here's the key. The way you correct for the transmission time depends on your initial interpretation of the physical setup. Whatever you do, as long as you remain consistent in your interpretation, you'll get a result that makes perfect, logical sense.
posted by chrismear at 6:38 PM on November 17, 2005
To recap for BorgLove and others:
posted by Ethereal Bligh at 7:12 PM on November 17, 2005
- "Temporal Mechanics" is not a physics term, but assuming it is (as in the case of the fictional Trek universe), it applies to time travel and not to "time dilation" as described in relativity physics. That is to say, disagreements about elapsed time are possible and are described in relativity; while travel backwards in time (or, presumably, travel forwards in time by the same physical principle that would be necessary for backward travel) is not possible, but in fiction it is how causality works in this new physics which is described as "temporal mechanics".
- The discrepancy of elapsed experienced by the characters of Dan Simmon's novel Hyperion is similar to, but distinct from the time dilation which is the consequence of relativity physics. It is dissimilar because Simmons is describing the effects of faster than light travel, about which modern physics, including relativity (but possibly excepting quantum) physics says nothing and does not allow.
- The difference between pronouncements of the impossibility of mechanized flight and the impossibility of FTL travel is qualitative. The former impossibility asserted was not the consequence of generally understood physical principles, but was a statement of physical intuition. The latter impossibility is asserted by relativity physics, which some people call the "most successful physical theory" in history. Relativity very definitely doesn't allow FTL, and relativity can be assumed to be fact as its well-understood and has been verified over and over again.
posted by Ethereal Bligh at 7:12 PM on November 17, 2005
A more direct example of the counter-intuitive nature of relativity that chrismear is describing is that two observers, in different inertial frames, will disagree on the exact timing of any event they both observe. Enough so that they might disagree even on the order of a series of events.
posted by Ethereal Bligh at 7:16 PM on November 17, 2005
posted by Ethereal Bligh at 7:16 PM on November 17, 2005
Finally, a bit more about weirdoactor's skepticism about the impossibility of faster-than-light travel.
It is very common for laypeople to compare this declaration of impossibility with a variety of declarations in the past that have proven to be false. As I point out in my note above, in many cases that false declaration was not a rigorous consequence of the dominant relevant scientific understanding, but rather was a simple intuitive statement as in the case of mechanized flight. So the comparison in these cases is invalid.
But it's certainly true that many things rigorously thought impossible in the past have been demonstrated to be possible later. As someone with a combination of science, history of science, and philosophy of science background, I feel like I can say something of substance in this context.
Firstly, the way in which old physical worldviews become invalidated and replaced by new ones almost always follows a certain pattern. This is Kuhn's famous "paradigm shift". There's one key thing about this that everyone should understand: rarely is the old theory discovered to be wrong in every sense—but, rather, it is discovered to apply to a limited portion of what the new theory describes. The canonical example is the transition to Relativity physics from Newtonian physics. A very big reason why it works this way is because empiricism is fundamentally a description of reality and, strictly speaking, causality and teleology are beyond its scope. The "strictly speaking" is important because, of course, science describes causal relationships every day. But causality is actually a more difficult philosophical concept than people realize; and you can see a hint of this when you think about how causality is related to teleology.
Teleology is the description of a series of events within the context of a purpose. Western science is absolutely not teleological. The way we intuitively think about reality, in contrast, is primarily (or, perhaps, always and necessarily!) teleological. We reason backwards, starting from the goal which assumes a causal series was initiated to reach.
An example of this is the question "why does it rain"? with the answer "because life needs the water".
The real breakthrough in western philosophy that allowed the invention of science was the eschewing of teleology, which we might call the "why questions" and the exclusive focus on empiricism, the "how questions". That is, description.
You can see that if western science is essentially description, then old theories will necessarily remain "true" when they are supplanted by new theories because the fact of what is described cannot change.
Anyway, if you don't see the subtle difficulties of causality, don't worry, in this context it's not that important.
[By the way, from this perspective it becomes obvious that "intelligent design" is emphatically not western science because it is by its very nature teleological. (In almost the very "worst" way it could be!)]
Most SF writers these days postulate "wormholes" because such a thing would not be, strictly speaking, FTL travel and you can hand-wave an implication for it in accepted physics.
From the perspective of my education and experience, the contemporary average layperson is far too credulous with regard to things that contemporary science finds unacceptable. However, I also find contemporary scientists too incredulous with regard to the the same class of things. That is to say, contemporary scientists are somewhat blinded by the status quo.
So what would my judgment be on, say, FTL? FTL as FTL is impossible. FTL via something like a "wormhole" is not strictly impossible but I think that the physical implications of such a thing are being hand-waved away by science fiction writers. I don't know what a "wormhole" would mean—it may run the gamut from being in principle in conflict with conscious life to having consequences even weirder that we see with standard relativity. I don't know. I'm pretty sure it wouldn't be just another way of "traveling faster than light".
posted by Ethereal Bligh at 8:11 PM on November 17, 2005
It is very common for laypeople to compare this declaration of impossibility with a variety of declarations in the past that have proven to be false. As I point out in my note above, in many cases that false declaration was not a rigorous consequence of the dominant relevant scientific understanding, but rather was a simple intuitive statement as in the case of mechanized flight. So the comparison in these cases is invalid.
But it's certainly true that many things rigorously thought impossible in the past have been demonstrated to be possible later. As someone with a combination of science, history of science, and philosophy of science background, I feel like I can say something of substance in this context.
Firstly, the way in which old physical worldviews become invalidated and replaced by new ones almost always follows a certain pattern. This is Kuhn's famous "paradigm shift". There's one key thing about this that everyone should understand: rarely is the old theory discovered to be wrong in every sense—but, rather, it is discovered to apply to a limited portion of what the new theory describes. The canonical example is the transition to Relativity physics from Newtonian physics. A very big reason why it works this way is because empiricism is fundamentally a description of reality and, strictly speaking, causality and teleology are beyond its scope. The "strictly speaking" is important because, of course, science describes causal relationships every day. But causality is actually a more difficult philosophical concept than people realize; and you can see a hint of this when you think about how causality is related to teleology.
Teleology is the description of a series of events within the context of a purpose. Western science is absolutely not teleological. The way we intuitively think about reality, in contrast, is primarily (or, perhaps, always and necessarily!) teleological. We reason backwards, starting from the goal which assumes a causal series was initiated to reach.
An example of this is the question "why does it rain"? with the answer "because life needs the water".
The real breakthrough in western philosophy that allowed the invention of science was the eschewing of teleology, which we might call the "why questions" and the exclusive focus on empiricism, the "how questions". That is, description.
You can see that if western science is essentially description, then old theories will necessarily remain "true" when they are supplanted by new theories because the fact of what is described cannot change.
Anyway, if you don't see the subtle difficulties of causality, don't worry, in this context it's not that important.
[By the way, from this perspective it becomes obvious that "intelligent design" is emphatically not western science because it is by its very nature teleological. (In almost the very "worst" way it could be!)]
Most SF writers these days postulate "wormholes" because such a thing would not be, strictly speaking, FTL travel and you can hand-wave an implication for it in accepted physics.
From the perspective of my education and experience, the contemporary average layperson is far too credulous with regard to things that contemporary science finds unacceptable. However, I also find contemporary scientists too incredulous with regard to the the same class of things. That is to say, contemporary scientists are somewhat blinded by the status quo.
So what would my judgment be on, say, FTL? FTL as FTL is impossible. FTL via something like a "wormhole" is not strictly impossible but I think that the physical implications of such a thing are being hand-waved away by science fiction writers. I don't know what a "wormhole" would mean—it may run the gamut from being in principle in conflict with conscious life to having consequences even weirder that we see with standard relativity. I don't know. I'm pretty sure it wouldn't be just another way of "traveling faster than light".
posted by Ethereal Bligh at 8:11 PM on November 17, 2005
Nerds and non-nerds: kindall is right for our universe.
But it's a story so it doesn't have to make sense. Don't waste a lot of energy trying to make it fit to what we know.
posted by Opposite George at 9:30 PM on November 17, 2005
But it's a story so it doesn't have to make sense. Don't waste a lot of energy trying to make it fit to what we know.
posted by Opposite George at 9:30 PM on November 17, 2005
Dammit you guys, we were having a perfectly good argument before you stepped in here and dragged us back on-topic.
posted by chrismear at 3:46 AM on November 18, 2005
posted by chrismear at 3:46 AM on November 18, 2005
there's a famous quote from einstein on the whole "sr doesn't include acceleration thing" - something along the lines of making a theory that couldn't handle acceleration would be like making a car whose wheels fell off at the slightest bump.
at least, i thought there was. can't find it with google.
anyway, here's validation from a heavweight.
posted by andrew cooke at 7:17 AM on November 18, 2005
at least, i thought there was. can't find it with google.
anyway, here's validation from a heavweight.
posted by andrew cooke at 7:17 AM on November 18, 2005
ah. not quite so heavyweight; i think it's a faq that baez just hosts. so my second appeal to authority is as weak as my first ;o)
posted by andrew cooke at 7:18 AM on November 18, 2005
posted by andrew cooke at 7:18 AM on November 18, 2005
Reading much of this theory reminds me (in a bad way) how similar religion and science really are.
posted by weirdoactor at 7:39 AM on November 18, 2005
posted by weirdoactor at 7:39 AM on November 18, 2005
ooo ooo can i guess?
- that they understand neither of them.
- or that they manage to annoy people who enjoy either.
but anyway, they're free to think they're similar. of course, they may be wrong. after all, everyone said aeroplanes were impossible, so what chance has anyone of making a factually correct statement?
etc etc.
but they have a point. science is rather like american fundamentalists (with protestant roots). what matters is that you go to the good book(s) and understand them yourself. and in that way, we are just preachers showing people where they may find their own enlightenment... (feynman's lectures, in particular ;o)
[on spell check: feynman -> enema]
oh, and the big difference, wod, in case you need the clue hammer: try praying for tv or a nuclear bomb. i won't wait up.
posted by andrew cooke at 8:02 AM on November 18, 2005
- that they understand neither of them.
- or that they manage to annoy people who enjoy either.
but anyway, they're free to think they're similar. of course, they may be wrong. after all, everyone said aeroplanes were impossible, so what chance has anyone of making a factually correct statement?
etc etc.
but they have a point. science is rather like american fundamentalists (with protestant roots). what matters is that you go to the good book(s) and understand them yourself. and in that way, we are just preachers showing people where they may find their own enlightenment... (feynman's lectures, in particular ;o)
[on spell check: feynman -> enema]
oh, and the big difference, wod, in case you need the clue hammer: try praying for tv or a nuclear bomb. i won't wait up.
posted by andrew cooke at 8:02 AM on November 18, 2005
[on spell check: feynman -> enema]
That may be the best thing to come from this thread.
posted by chrismear at 8:26 AM on November 18, 2005
That may be the best thing to come from this thread.
posted by chrismear at 8:26 AM on November 18, 2005
try praying for tv or a nuclear bomb.
So, scientists never hold hopes that a combination of lessons learned from previous attempts produces the desired result during research? Especially when the result of the research determines next years funding levels. That's different from "faith" in what way?
The religious revel in talking about how parables from their various mythologies are lessons that the "faithful" can learn from. These differ from those engaging in a new experiment learning from previous research and hypotheses in what way?
posted by weirdoactor at 8:41 AM on November 18, 2005
So, scientists never hold hopes that a combination of lessons learned from previous attempts produces the desired result during research? Especially when the result of the research determines next years funding levels. That's different from "faith" in what way?
The religious revel in talking about how parables from their various mythologies are lessons that the "faithful" can learn from. These differ from those engaging in a new experiment learning from previous research and hypotheses in what way?
posted by weirdoactor at 8:41 AM on November 18, 2005
So, scientists never hold hopes that a combination of lessons learned from previous attempts produces the desired result during research?
Of course they do. But it's just a superficial hope, on a human level, that their work for the last five years hasn't just been barking up the wrong alley. It's nothing to do with them having blind faith in the existing theory.
The religious revel in talking about how parables from their various mythologies are lessons that the "faithful" can learn from. These differ from those engaging in a new experiment learning from previous research and hypotheses in what way?
Your intepretation of a parable, and the lessons you learn from it, depend upon the amount of faith and the religious temperement you had before hearing the parable. To the extent that our interpretations are influenced by your belief or my non-belief in the religion, you can't prove that your interpretation of the parable is more 'correct' than mine. It's truly a matter of faith -- blind faith.
Drawing a lesson like "forgiving people is good" from the parable of the Prodigal Son is pretty reasonable, but it's still fuzzy philosophising, not logical deduction. The parable doesn't prove that moral conclusion.
A sound, scientific experimental result, on the other hand, can disprove a theory outright. And it doesn't matter what your opinions or hopes were before the experiment was done -- the result and its consequences are found out by logical deduction; there is no multitude of equally valid 'interpretations'.
Sure, you may be positively seething that your pet theory of Penguin Spaghetti Wormholes has been comprehensively shown to be false by physical experiment. You may have had a lot of faith in it up to now. But if you are a good scientist, you will discard that faith in the light of the experimental evidence.
Confirmation by physical experiment the ultimate touchstone of any theory. The amount of blind faith that you have in a theory is completely irrelevent.
That's the difference. In science, we test the theories to see whether they are worthy of our faith in them. In religion, we are tested to see whether our faith is worthy.
Science is about theories which are disprovable. Religion is about ideas which are unprovable.
posted by chrismear at 9:48 AM on November 18, 2005
Of course they do. But it's just a superficial hope, on a human level, that their work for the last five years hasn't just been barking up the wrong alley. It's nothing to do with them having blind faith in the existing theory.
The religious revel in talking about how parables from their various mythologies are lessons that the "faithful" can learn from. These differ from those engaging in a new experiment learning from previous research and hypotheses in what way?
Your intepretation of a parable, and the lessons you learn from it, depend upon the amount of faith and the religious temperement you had before hearing the parable. To the extent that our interpretations are influenced by your belief or my non-belief in the religion, you can't prove that your interpretation of the parable is more 'correct' than mine. It's truly a matter of faith -- blind faith.
Drawing a lesson like "forgiving people is good" from the parable of the Prodigal Son is pretty reasonable, but it's still fuzzy philosophising, not logical deduction. The parable doesn't prove that moral conclusion.
A sound, scientific experimental result, on the other hand, can disprove a theory outright. And it doesn't matter what your opinions or hopes were before the experiment was done -- the result and its consequences are found out by logical deduction; there is no multitude of equally valid 'interpretations'.
Sure, you may be positively seething that your pet theory of Penguin Spaghetti Wormholes has been comprehensively shown to be false by physical experiment. You may have had a lot of faith in it up to now. But if you are a good scientist, you will discard that faith in the light of the experimental evidence.
Confirmation by physical experiment the ultimate touchstone of any theory. The amount of blind faith that you have in a theory is completely irrelevent.
That's the difference. In science, we test the theories to see whether they are worthy of our faith in them. In religion, we are tested to see whether our faith is worthy.
Science is about theories which are disprovable. Religion is about ideas which are unprovable.
posted by chrismear at 9:48 AM on November 18, 2005
So, when a long-held accepted theory is proven to be incorrect (and I'm not talking about small discoveries; I'm talking world changing, like those of Curie & Pasteur), and the scientific world is forced to re-think theory for decades, and scientists who had "preached" the previously held theories as "gospel" are now thought of as hacks... this isn't like similar events in religion (Martin Luther, the Mormons, Evangelicals, etc.)?
Maybe not along the lines of proveable theory, as you spoke of; but in terms of the way beliefs are held and expressed, the angry reactionism, and the "they don't know what they're talking about, we are the only true church" sort of attitude. That's how I find them similar.
posted by weirdoactor at 10:53 AM on November 18, 2005
Maybe not along the lines of proveable theory, as you spoke of; but in terms of the way beliefs are held and expressed, the angry reactionism, and the "they don't know what they're talking about, we are the only true church" sort of attitude. That's how I find them similar.
posted by weirdoactor at 10:53 AM on November 18, 2005
Thanks for the explanation, chrismear, and thanks for the link, andrew cooke.
For the record, I have a modern physics text book not five years old, which I was using to refresh my memory, that quite plainly states that SR can't handle acceleration, which seems flat-out false. Ain't that some shit? I thought it used acceleration to explain the lack of symmetry in the twin paradox, but it actually uses "the jump from one inertial frame to another" which I'm not quite sure is different.
Good stuff to know.
Weirdoactor: you need to read up on what empiricism is. It plays no part in religion. It is the foundation of science. Falsifiability is a feature, not bug, in science. Religion is never falsifiable.
The two aren't alike at all, and the similarity you see is almost entirely superficial. You are confusing hubris with science.
posted by teece at 11:15 AM on November 18, 2005
For the record, I have a modern physics text book not five years old, which I was using to refresh my memory, that quite plainly states that SR can't handle acceleration, which seems flat-out false. Ain't that some shit? I thought it used acceleration to explain the lack of symmetry in the twin paradox, but it actually uses "the jump from one inertial frame to another" which I'm not quite sure is different.
Good stuff to know.
Weirdoactor: you need to read up on what empiricism is. It plays no part in religion. It is the foundation of science. Falsifiability is a feature, not bug, in science. Religion is never falsifiable.
The two aren't alike at all, and the similarity you see is almost entirely superficial. You are confusing hubris with science.
posted by teece at 11:15 AM on November 18, 2005
If scientists (who in the eye of the beholder, represent all science) exhibit such hubris to both the public and to each other; how can we not compare this to religious leaders (who in the eye of the beholder, represent all religion) exhibiting similar hubris? When Pat Robertson says that Dover, PA will feel the wrath of "god", does that mean all religion is stupid? No. But can an observer feel that religion gets a black eye from this hubris? Yes.
Again, I'm not talking provable theory, or how religion and science differ in the grounds of observation and experiment. I'm talking about the hubris you mentioned, and how it affects the perception of both science and religion, and how they are similar BECAUSE of this hubris. I am NOT attempting to compare how science and religion operate, as your comments would tend to indicate; merely how they are perceived by the "common" folk.
posted by weirdoactor at 11:41 AM on November 18, 2005
Again, I'm not talking provable theory, or how religion and science differ in the grounds of observation and experiment. I'm talking about the hubris you mentioned, and how it affects the perception of both science and religion, and how they are similar BECAUSE of this hubris. I am NOT attempting to compare how science and religion operate, as your comments would tend to indicate; merely how they are perceived by the "common" folk.
posted by weirdoactor at 11:41 AM on November 18, 2005
Put another way: have you ever seen a black hole? Up close? Seen what it does? No. You haven't. But you believe in them, right? Sight unseen. And if someone told you that black holes did not exist, you would tell them that they were incorrect.
Substitute "god" (or angels, or UFOs, etc.) for "black hole".
posted by weirdoactor at 11:52 AM on November 18, 2005
Substitute "god" (or angels, or UFOs, etc.) for "black hole".
posted by weirdoactor at 11:52 AM on November 18, 2005
Oh, okay. I see what you're getting at now.
Yes, that's actually a pretty good point. Without that 'insider's knowledge' of science, it can externally seem a lot like the preaching of religion.
In my view it's unfortunate that there's so much politics and personality in science. But as social, emotional animals, it's probably unavoidable. Maybe it's necessary to have that kind of intense attachment to our work and monkey curiosity in order to drive forward in science and exploration. I don't know.
But you're right; when it bubbles to the surface, it doesn't look particularly good.
posted by chrismear at 12:17 PM on November 18, 2005
Yes, that's actually a pretty good point. Without that 'insider's knowledge' of science, it can externally seem a lot like the preaching of religion.
In my view it's unfortunate that there's so much politics and personality in science. But as social, emotional animals, it's probably unavoidable. Maybe it's necessary to have that kind of intense attachment to our work and monkey curiosity in order to drive forward in science and exploration. I don't know.
But you're right; when it bubbles to the surface, it doesn't look particularly good.
posted by chrismear at 12:17 PM on November 18, 2005
From my own personal experience in the entertainment world; I would agree that a certain amount of hubris seems to come part and parcel with the creative spark. I also guarantee you that watching two theatre geeks argue that Edward Albee is a better playwright than Arthur Miller would bear a remarkably close resemblance to a religious debate. Because for them theatre IS a religion. I would posit that it's also a similar dynamic for those who feel strongly about science.
Thanks for seeing my vague, terribly specific side of this subject. Heh.
posted by weirdoactor at 12:23 PM on November 18, 2005
Thanks for seeing my vague, terribly specific side of this subject. Heh.
posted by weirdoactor at 12:23 PM on November 18, 2005
Oy vey, weirdoactor, oy vey.
Indirect evidence of the existence of black holes is strong. Many non-scientists don't understand the power of indirect evidence, and mistake it for magic or faith. This is an ignorance on their part, not an actual problem with indirect evidence.
Again: quit ignoring empiricism. Black holes and angels or god are not even in the same game, let alone ball park.
If someone told me they did not "believe" in black holes, I would ignore them. If someone told me they thought they did not exist, and gave a theory for why, and further gave an empirical way to test that theory, I would only tell them they were wrong if their theory did not work. Very, very big difference from someone that tells me angels exist, and affect their daily lives.
Hubris is a human trait. The difference between scientific hubris and religious hubris is simple: you can check the former for correctness, not the latter. That makes all the difference in the world.
If science seems like religion to you, it is only because of an ignorance of science. While that is a real, practical problem for science (it's easy for hucksters to fool people with pseudosicence), it does not mean science is like religion.
The reality is that to two are entirely different.
posted by teece at 12:33 PM on November 18, 2005
Indirect evidence of the existence of black holes is strong. Many non-scientists don't understand the power of indirect evidence, and mistake it for magic or faith. This is an ignorance on their part, not an actual problem with indirect evidence.
Again: quit ignoring empiricism. Black holes and angels or god are not even in the same game, let alone ball park.
If someone told me they did not "believe" in black holes, I would ignore them. If someone told me they thought they did not exist, and gave a theory for why, and further gave an empirical way to test that theory, I would only tell them they were wrong if their theory did not work. Very, very big difference from someone that tells me angels exist, and affect their daily lives.
Hubris is a human trait. The difference between scientific hubris and religious hubris is simple: you can check the former for correctness, not the latter. That makes all the difference in the world.
If science seems like religion to you, it is only because of an ignorance of science. While that is a real, practical problem for science (it's easy for hucksters to fool people with pseudosicence), it does not mean science is like religion.
The reality is that to two are entirely different.
posted by teece at 12:33 PM on November 18, 2005
Hubris is a human trait.
Well. Judging from your responses, I'm guessing that you are indeed human.
posted by weirdoactor at 12:54 PM on November 18, 2005
Well. Judging from your responses, I'm guessing that you are indeed human.
posted by weirdoactor at 12:54 PM on November 18, 2005
"...scientists who had 'preached' the previously held theories as 'gospel' are now thought of as hack."
That's where you've gone wrong right there. That doesn't happen.
Look, I know that I always sound as if I think this, but right here I'm going to declare it: I have more expertise on this question you're asking or the point you're making, weirdoacter, than anyone else here. I've studied in university the point at which philosophy and science meet, I am quite aware of the way in which the typical scientist is a naive realist, I think a great deal about what it means to "know" something, and I've studied a great deal of theology (too much), as well. And you're wrong. You're just plain wrong.
Science is not like religion. It's more like philosophy than scientists want to admit, but it's not very much like religion at all.
I will grant you that a good argument could be made that in many ways it functions in our society similarly to religion. But that's not the same as saying it's very much like religion because what science is goes far beyond merely the sociology of it that is comparable to religion belief and practice.
posted by Ethereal Bligh at 1:33 PM on November 18, 2005
That's where you've gone wrong right there. That doesn't happen.
Look, I know that I always sound as if I think this, but right here I'm going to declare it: I have more expertise on this question you're asking or the point you're making, weirdoacter, than anyone else here. I've studied in university the point at which philosophy and science meet, I am quite aware of the way in which the typical scientist is a naive realist, I think a great deal about what it means to "know" something, and I've studied a great deal of theology (too much), as well. And you're wrong. You're just plain wrong.
Science is not like religion. It's more like philosophy than scientists want to admit, but it's not very much like religion at all.
I will grant you that a good argument could be made that in many ways it functions in our society similarly to religion. But that's not the same as saying it's very much like religion because what science is goes far beyond merely the sociology of it that is comparable to religion belief and practice.
posted by Ethereal Bligh at 1:33 PM on November 18, 2005
Well. Judging from your responses, I'm guessing that you are indeed human.
Sigh, I'm not trying to be a dick, weirdoactor. You started this by saying:
Reading much of this theory reminds me (in a bad way) how similar religion and science really are.
You're way off base with that. From your clarifications, it seems you meant to say something about human behavior, and nothing about science and religion.
posted by teece at 2:59 PM on November 18, 2005
Sigh, I'm not trying to be a dick, weirdoactor. You started this by saying:
Reading much of this theory reminds me (in a bad way) how similar religion and science really are.
You're way off base with that. From your clarifications, it seems you meant to say something about human behavior, and nothing about science and religion.
posted by teece at 2:59 PM on November 18, 2005
it seems you meant to say something about human behavior
Yes. About humans who feel strongly about science, as compared to humans who feel strongly about religion. Or anything someone feels strongly about, like theatre, as I stated above.
My mistake was in looking ONLY at religion and science in making my comment. It obviously could be applied to any number of areas that one feels strongly about; in that they feel that only their way/theory/opinion is the true way. Sincere apologies for my narrow focus.
Now. That said, I still feel that there are some (some...NOT all) people in science who feel as devoutly about their theories as do the religious about their faith. Example: Sagan's dismissal of Hawking's theory about why time travel is impossible:
One of Hawking's arguments in the conjecture is that we are not awash in thousands of time travelers from the future, and therefore time travel is impossible. This argument I find very dubious, and it reminds me very much of the argument that there cannot be intelligences elsewhere in space, because otherwise the Earth would be awash in aliens. I can think half a dozen ways in which we could not be awash in time travelers, and still time travel is possible.
"This argument I find very dubious" is a polite way of saying "Bullshit, Stephen", as if Hawking's theory had no merit merely because it conflicted with Sagan's own theories/feelings/hopes/FAITH that alien life truly does exists (something I happen to agree with).
I also hope that time travel exists. I need to go back in time and tell my young self not to eat so much ice cream and fried food.
posted by weirdoactor at 3:30 PM on November 18, 2005
Yes. About humans who feel strongly about science, as compared to humans who feel strongly about religion. Or anything someone feels strongly about, like theatre, as I stated above.
My mistake was in looking ONLY at religion and science in making my comment. It obviously could be applied to any number of areas that one feels strongly about; in that they feel that only their way/theory/opinion is the true way. Sincere apologies for my narrow focus.
Now. That said, I still feel that there are some (some...NOT all) people in science who feel as devoutly about their theories as do the religious about their faith. Example: Sagan's dismissal of Hawking's theory about why time travel is impossible:
One of Hawking's arguments in the conjecture is that we are not awash in thousands of time travelers from the future, and therefore time travel is impossible. This argument I find very dubious, and it reminds me very much of the argument that there cannot be intelligences elsewhere in space, because otherwise the Earth would be awash in aliens. I can think half a dozen ways in which we could not be awash in time travelers, and still time travel is possible.
"This argument I find very dubious" is a polite way of saying "Bullshit, Stephen", as if Hawking's theory had no merit merely because it conflicted with Sagan's own theories/feelings/hopes/FAITH that alien life truly does exists (something I happen to agree with).
I also hope that time travel exists. I need to go back in time and tell my young self not to eat so much ice cream and fried food.
posted by weirdoactor at 3:30 PM on November 18, 2005
No, Sagan is right: it's bad reasoning whichever side of the fence you're on. I feel the same way about strong anthropic reasoning.
posted by Ethereal Bligh at 3:36 PM on November 18, 2005
posted by Ethereal Bligh at 3:36 PM on November 18, 2005
This thread is closed to new comments.
It's even experimentally verified. Very well verified. This is the way the universe works. Time is not absolute.
posted by teece at 11:49 AM on November 17, 2005