> Japan's strong cultural preference for simplicity in design
What? It's the exact opposite.
This is my only real complaint about Japan. I can't stand the shops here. There are colored flashy signs everywhere, and you can always hear at least a dozen different adverts at the same time.
Likewise every device is ridiculously complex. My fan has 6 buttons and a remote control. Just to blow air! And the toilet has a dozen buttons and two knows to adjust seat and water temperature. Everything is completely overdesigned.
Theories tend not to be proven wrong, but rather the range in which they work gets reduced.
For example, we can see galaxies moving away from us at several times the speed of light. I suppose you could say that that shows SR to be wrong, although a better way is to just say that SR only applies to flat space that isn't expanding.
No, I don't think/you/ can comment on such articles.
But I don't see why you think slashdot is only for computer science people. This is supposed to be a site for geeks in general, so why do think physcists wont come?
There seem to be a few misconceptions from the people that have replied.
If we take "FTL" to strictly mean travelling faster than light travelling nearby, then in any macroscopic ordinary sense special relativity doesn't let you do this. There are a few exceptions - for example if the curvature of space is such that it can no longer be considered flat, such as near extreme black holes. Or for extremely short periods of time.
But often this definition is too strict, and "FTL" proponents would be happy with arriving someone else faster than it would take light to travel that same journey, without getting caught up in the details of whether you were actually travelling faster than light at any point. There are various possible loopholes - teleportation, moving space itself, using a "hyperspace" to travel in, and so on.
Scifi tends to call travelling in "hyperspace" as FTL despite at no point actually travelling faster than light.
This sort of thing is acceptable in SR, as long as whatever method use always uses a fixed frame of reference (e.g. you can't move hyperspace itself and you have an upper speed limit in hyperspace, or that you can only teleport instaneously from the point of view of the microwave background radiation etc)
Such as? I don't know of any math that breaks down if that happens.
Afaik, instaneous teleportation (from the point of view of a fixed frame of reference - for example the microwave background radiation) - does not cause any problems.
I pay for lwn.net which writes complex technical articles about the linux kernel.
I like what they do:
1) All (I think?) the articles become free after some period of time. For the weekly articles it's after one week. 2) They have an option of saying that you are poor, in which case you pay half price 3) They pay for very well written reports that I don't see elsewhere. 4) It's cheap enough that I simply set up a direct debit and don't worry about it.
I suspect that the way that it would be done is to have a solar sail just orbit around the sun, picking up speed for 20 years.
Then we put some humans in a small 'pod' and fling them up to the solar sail in a few day/weeks/months. They then board the big solar ship and the whole thing flings off in the direction that we want to go in. Then we coast a continual but high speed all the way there.
When we have arrived we would place the ship in an orbit and the humans would enter the small pod again and slow down by aerobraking on the atomopshere of the planet.
> I wonder how its m/s acceleration compares to that of an ION drive.
You can see most of the different designs are for a thrust of 100-1000 mN, compared to the 1mN of this solar sail. Of course, the solar sail could just be made a lot bigger, and the solar sail actually works compared to random theoretical numbers for a theoretical drive:)
> Assuming uniform pressure (a stretch I know) how long until it reaches 99% of the speed of light?
The force on it will be:
F = gamma*ma
So:
(m*gamma)/F = 1/a m/F * (1/sqrt(1-v^2/c^2)) = dt/dv m/F * integrate (1/sqrt(1-v^2/c^2)) dv = t
Integrating v from 0 to 0.99c gives:
integrate (1/sqrt(1-v^2/c^2)) dv from 0 to 0.99c = 1.429c
so:
m/F *1.429c = t
((700 pounds) / (1.12 millinewton)) * 1.42926 * c = 3 849 311.08 years
So it would take 3.8 million years. Without the relativistic correction we get a result of v/a = t = 0.99c/0.3048m/s = 31 years!
What an amazing difference the correction makes. The trouble is that by the time it is going at 99% the speed of the light the mass is 1/sqrt(1-0.99) = 10 times heavier.
The nearest star system is 4 light years away, so we wouldn't get even a fraction close to the speed of light, so the simple formula would be fine to use - so
At which time we would be traveling at v = at = 12% the speed of light. This means that our assumption that we don't go a significant fraction of light is okay, but a bit dodgy. Our answer will be about by approx 5%. So let's say 17 years.
However it might be better to accelerate half the journey and deaccelerated the second half, so that we arrive stationary instead of zipping past it. In this case we need to multiply by sqrt(2) so the time is 17*sqrt(2) = 24 years.
Not too bad - about 25 years. Time lag on communication at a distance of 4 light years would be, well, 4 years. So 8 years if you want a roundtrip question-response.
> Based on total force of 1.12mN and assuming a static photon count, that looks like an acceleration of 4E-6 m/s^2, so each day it will pick up a velocity of about 0.3 m/s.
Yep. ( ((1.12 millinewton) / (700 pounds)) * (1 day) = 0.304767031 m / s )
"Fring was using Skype software in a way it wasn’t designed to be used – and in a way which is in breach of Skype’s API Terms of Use and End User License Agreement."
Note that they don't say what, and given what other people have said here it would fit in perfectly that what is actually happening is:
1) Skype are notoriously slow about adding new features to the official client 2) Fring added the features themselves. 3) Skype told Fring to stop adding features that they haven't added to the official client 4) Fring did not want to remove the features that their users demanded and in frustration and to get attention they removed video support. 5) Both sides feel that they are the victim.
This seems to fit in with what the comments are saying. For example "People want to use Skype NOW!!!! Skype takes FOREVER to release updates for their iOS software!! You had a working demo of Skype on iOS 4.0 back when Apple first announced iOS 4.0 yet there STILL hasn't been a release months later. "
and "And the whole issue with charging for Skype Over 3G? I already pay you for a monthly subscription, now I will have to pay extra to use it on my iPhone over 3G? "
It's great that it worked for you, but lots of people aren't receptive to even that.
Richard Dawkins did a documentary where he went into a poor school where the majority of students believed the world was just 6000 years old etc. He took a class to the beach to look for fossils. He thought that if he could just get the kids to find a real fossil for themselves, and actually hold it, then it might give them (as you put it) a feeling for "Hey, maybe they really aren't just making all this shit up."
Did it work? Hell no. The documentary tries to hide that, but what they don't say seems to be as revealing as what they do say. The whole class managed to find only 2 fossils (This is abysmal - it was a beach where you could find dozens by yourself in a day). And they only showed interviews afterwards of two of the classmates, and all they would say was pretty much "it was durrr okay"
So what is the purpose in licensing as BSD instead of the LGPL if you're then going to complain about anyone that actually uses the difference between them.
Slashdot Mirror
> Japan's strong cultural preference for simplicity in design
What? It's the exact opposite.
This is my only real complaint about Japan. I can't stand the shops here. There are colored flashy signs everywhere, and you can always hear at least a dozen different adverts at the same time.
Likewise every device is ridiculously complex. My fan has 6 buttons and a remote control. Just to blow air! And the toilet has a dozen buttons and two knows to adjust seat and water temperature. Everything is completely overdesigned.
Theories tend not to be proven wrong, but rather the range in which they work gets reduced.
For example, we can see galaxies moving away from us at several times the speed of light. I suppose you could say that that shows SR to be wrong, although a better way is to just say that SR only applies to flat space that isn't expanding.
"clearly you think otherwise"
No, I don't think /you/ can comment on such articles.
But I don't see why you think slashdot is only for computer science people. This is supposed to be a site for geeks in general, so why do think physcists wont come?
How would you even start to approach to proving that?
You'd need to consider all the conflicts that could have been, but weren't because the issue disappeared due to diplomacy early on, no?
There seem to be a few misconceptions from the people that have replied.
If we take "FTL" to strictly mean travelling faster than light travelling nearby, then in any macroscopic ordinary sense special relativity doesn't let you do this. There are a few exceptions - for example if the curvature of space is such that it can no longer be considered flat, such as near extreme black holes. Or for extremely short periods of time.
But often this definition is too strict, and "FTL" proponents would be happy with arriving someone else faster than it would take light to travel that same journey, without getting caught up in the details of whether you were actually travelling faster than light at any point. There are various possible loopholes - teleportation, moving space itself, using a "hyperspace" to travel in, and so on.
Scifi tends to call travelling in "hyperspace" as FTL despite at no point actually travelling faster than light.
This sort of thing is acceptable in SR, as long as whatever method use always uses a fixed frame of reference (e.g. you can't move hyperspace itself and you have an upper speed limit in hyperspace, or that you can only teleport instaneously from the point of view of the microwave background radiation etc)
Such as? I don't know of any math that breaks down if that happens.
Afaik, instaneous teleportation (from the point of view of a fixed frame of reference - for example the microwave background radiation) - does not cause any problems.
Just because you're an idiot doesn't mean we all are.
Are you seriously trying to propose that us physcists have no interest in reading geek news?
I pay for lwn.net which writes complex technical articles about the linux kernel.
I like what they do:
1) All (I think?) the articles become free after some period of time. For the weekly articles it's after one week.
2) They have an option of saying that you are poor, in which case you pay half price
3) They pay for very well written reports that I don't see elsewhere.
4) It's cheap enough that I simply set up a direct debit and don't worry about it.
Yeah, I think you're right.
The heat is getting to me and making me grouchy, sorry.
This is what slashdot has been reduced to?
There are dozens of interesting real scientific pieces of news recently, but slashdot decides to focus on this..
sigh
I suspect that the way that it would be done is to have a solar sail just orbit around the sun, picking up speed for 20 years.
Then we put some humans in a small 'pod' and fling them up to the solar sail in a few day/weeks/months. They then board the big solar ship and the whole thing flings off in the direction that we want to go in. Then we coast a continual but high speed all the way there.
When we have arrived we would place the ship in an orbit and the humans would enter the small pod again and slow down by aerobraking on the atomopshere of the planet.
> I wonder how its m/s acceleration compares to that of an ION drive.
If you look at:
http://en.wikipedia.org/wiki/Ion_thruster#Comparisons
You can see most of the different designs are for a thrust of 100-1000 mN, compared to the 1mN of this solar sail. Of course, the solar sail could just be made a lot bigger, and the solar sail actually works compared to random theoretical numbers for a theoretical drive :)
> Assuming uniform pressure (a stretch I know) how long until it reaches 99% of the speed of light?
The force on it will be:
F = gamma*ma
So:
(m*gamma)/F = 1/a
m/F * (1/sqrt(1-v^2/c^2)) = dt/dv
m/F * integrate (1/sqrt(1-v^2/c^2)) dv = t
Integrating v from 0 to 0.99c gives:
integrate (1/sqrt(1-v^2/c^2)) dv from 0 to 0.99c = 1.429c
so:
m/F *1.429c = t
((700 pounds) / (1.12 millinewton)) * 1.42926 * c = 3 849 311.08 years
So it would take 3.8 million years. Without the relativistic correction we get a result of v/a = t = 0.99c/0.3048m/s = 31 years!
What an amazing difference the correction makes. The trouble is that by the time it is going at 99% the speed of the light the mass is 1/sqrt(1-0.99) = 10 times heavier.
The nearest star system is 4 light years away, so we wouldn't get even a fraction close to the speed of light, so the simple formula would be fine to use - so
x = 1/2 at^2 =>
t = sqrt(2x/a)
So:
sqrt((2 * (4 light years)) / (0.305 (m / (s^2)))) = 15.7854904 years
At which time we would be traveling at v = at = 12% the speed of light. This means that our assumption that we don't go a significant fraction of light is okay, but a bit dodgy. Our answer will be about by approx 5%. So let's say 17 years.
However it might be better to accelerate half the journey and deaccelerated the second half, so that we arrive stationary instead of zipping past it. In this case we need to multiply by sqrt(2) so the time is 17*sqrt(2) = 24 years.
Not too bad - about 25 years. Time lag on communication at a distance of 4 light years would be, well, 4 years. So 8 years if you want a roundtrip question-response.
> Based on total force of 1.12mN and assuming a static photon count, that looks like an acceleration of 4E-6 m/s^2, so each day it will pick up a velocity of about 0.3 m/s.
Yep. ( ((1.12 millinewton) / (700 pounds)) * (1 day) = 0.304767031 m / s )
I believe Skype, but I don't side with them.
Look at what skype said:
"Fring was using Skype software in a way it wasn’t designed to be used – and in a way which is in breach of Skype’s API Terms of Use and End User License Agreement."
Note that they don't say what, and given what other people have said here it would fit in perfectly that what is actually happening is:
1) Skype are notoriously slow about adding new features to the official client
2) Fring added the features themselves.
3) Skype told Fring to stop adding features that they haven't added to the official client
4) Fring did not want to remove the features that their users demanded and in frustration and to get attention they removed video support.
5) Both sides feel that they are the victim.
This seems to fit in with what the comments are saying. For example
"People want to use Skype NOW!!!! Skype takes FOREVER to release updates for their iOS software!! You had a working demo of Skype on iOS 4.0 back when Apple first announced iOS 4.0 yet there STILL hasn't been a release months later. "
and
"And the whole issue with charging for Skype Over 3G? I already pay you for a monthly subscription, now I will have to pay extra to use it on my iPhone over 3G? "
> IQ tests show a correlation with income and with education level.
Income, kinda, but wealth, not at all.
I found this highly interesting: http://www.iapsych.com/articles/zagorsky2007ip.pdf
I don't know, but I have to use the hell that is "Open-Xchange server".
It's great that it worked for you, but lots of people aren't receptive to even that.
Richard Dawkins did a documentary where he went into a poor school where the majority of students believed the world was just 6000 years old etc. He took a class to the beach to look for fossils. He thought that if he could just get the kids to find a real fossil for themselves, and actually hold it, then it might give them (as you put it) a feeling for "Hey, maybe they really aren't just making all this shit up."
Did it work? Hell no. The documentary tries to hide that, but what they don't say seems to be as revealing as what they do say. The whole class managed to find only 2 fossils (This is abysmal - it was a beach where you could find dozens by yourself in a day). And they only showed interviews afterwards of two of the classmates, and all they would say was pretty much "it was durrr okay"
(Link http://www.secularism.org.uk/whydawkinsisrightandhiscriticsar.html )
I've been loving skype chat. It lets my mum see my baby daughter and talk to her, even though we are on opposite sides of the globe.
So what is the purpose in licensing as BSD instead of the LGPL if you're then going to complain about anyone that actually uses the difference between them.
> This latest trend of GPL projects relicensing BSD code so the BSD project can't use the improvements makes me seethe those.
But they _chose_ to say that BSD code can be relicensed in such a way. If they wanted to keep the improvements then they should have chosen the LGPL.
True. I know several people who have legally purposed more books, DVDs or games than they can actually consume.
I know I'm guilty of that in a small way - I have about 6 games that I've bought but haven't touched 6 months later.
LOL.
I would say that if you did have evidence, you would have just posted it already instead of complaining that noone looks at your evidence.
And if you do post your evidence, it will probably be non-verifiable, non-testable and non-repeatable evidence.
How can you investigate the options when there is no evidence either way?
Right, which is somewhat related to the "tivoization" ( http://en.wikipedia.org/wiki/Tivoization )