These stories always say it was Einstein's great blunder and it has been vindicated, but it really hasn't. The reason Einstein put it in was that he couldn't find any solutions to his equations that resulted in a static universe. (At the time, Hubble's revolutionary results on the recession of distant galaxies had not been completed, so it was thought the universe must be static) All of his model universes were expanding or contracting. So he added the constant to balance out the contraction in his favoured model (which was also closed, another historical assumption in cosmology that has been disposed of).
OK, but the cosmological constant we see now is being used to explain the _acceleration_ of the universe, nothing like what Einstein put the constant in for. His blunder wasn't really the constant, it was the assumption that the universe was static, which turned out to be totally wrong.
But you have to admire Einstein - out of pure thought and mathematics he produced a theory which is still held up as a foundation of modern physics, even though practically every cosmological observation was made years after he published it (and all the observations have supported the theory to great accuracy). Compare this to, say, quantum mechanics, where many theorists struggled for decades to explain observations that had already been made, and Einstein's one-man theory is truly impressive.
It is based on the diameter of the primary mirror (~10m for SALT). The equal is the prototype which SALT is based on, the HET in Texas (I think). Resolution depends on diameter so it would also have the best resolution, but the Earth's atmosphere tends to distort things too much. This is why the Hubble Space Telescope (which is a mere 2.4M) is so valuable - no atmospheric disturbance. However, having a giant mirror means that the telescope can observe faint objects in less time than anything in space at the moment, so can take much higher resolution spectra.
The actual telescope can't use the whole mirror at once because of the design. The telescope only moves in azimuth, which saves a huge amount of cost but means that only a small part of the mirror is used at any one time. As the target rotates around the sky the area on the telescope moves across the mirror to allow longer exposures.
SALT also has very high sensitivity to short wavelengths (blue/UV) which is probably the best of any large telescope, or at least close.
Feynman also once bet (but only a nickel or something) against Fred Hoyle, whose book claimed that a space traveller flying out along the axis of the Milky Way at close to the speed of light would see a fishbowl-like effect with a red rim and a blue bowl.
Turns out Feynman was wrong (!). It's a fun problem if you want to try it : ) Also goes to show that even the brilliant intuition of Feynman can be fooled by the wierdness of relativity.
Another example is a bet of a case of whiskey by Brian Schmidt and Ken Freeman I think (two astronomers working in Australia) about the value of the Hubble constant being greater than or less than 70 km per sec per megaparsec. Unfortunately the uncertainty bars were still to big after the time limit of the bet expired.
Because of relativity itself light always travels at the same speed for everyone - there is no way to slow it down to rest and have it turn into mass because no matter how fast we go we can't catch up to light. If, for example, we are travelling at 99% of the speed of light and as we go past someone they shoot some photons in front of us, they still speed ahead of us at the speed of light.
On the other hand, because of Einstein's later General Relativity we know that photons act as if they have mass when they are affected by or producing gravity. Light is deflected by gravitational fields around stars for example, and the combined energy of the photons in the universe was a major part of the early universe's mass/energy. (Now the radiation is too spread out to have much of an effect)
One of the most fundamental things in relativity is the idea that only massive particles/objects can be brought to rest. (Note that the idea that mass somehow increases as you speed something up is very out of date now. Physicists just use a fixed, so-called rest mass for particles at any speed. It is really the momentum and total energy that increase vastly as you approach the speed of light)
Also, by measuring the expansion rate of the universe over a very long time (ie. billions of years), and making observations of the Cosmic Microwave Backgound (CMB, the left over radiation from around 300000 years after the Big Bang) we can calculate the amount of matter it must contain. Then from models of the Big Bang and the CMB observations we can also find the amount of 'normal' matter (ie atoms), which comes to about 4% of the so called 'critical density', which is the amount of matter/energy required to have the universe be spatially flat (expands forever but tends toward zero expansion rate as time goes to infinity)
Since the amount of matter is measured to be around 25% this means dark matter must be around 20% of the critical density.
Incidentally, this also means that 75% of the energy/matter in the universe is 'dark energy', since the cosmic microwave background indicates the universe is almost exactly flat.
However, the importance of each constituent changes over time because essentially the dark energy is proportional to the size of the universe and when it was much smaller the matter was more concentrated so it had a far greater influence. Therefore for studies of the early evolution of the universe the dark energy is unimportant, and since dark matter is most of the total matter the models can just use dark matter alone. At present, however, the dark energy appears to be causing an acceleration of the expansion rate, which is seen using distant supernovae. This is how the 75% figure is worked out.
NB: Nobody can explain what the dark matter or dark energy is right now! This is by far the most important problem in Cosmology, and there are many , many competing theories.
It may be the worst time in history right now, but do you honestly expect things to be better in say, 5 years time? Will the Senate quit their corporate sponsorship? Will the Senate be less pro-buisiness? Will the gap between rich and poor get smaller?
And are Democratic Senators any less in the pocket of buisiness?
Sorry to be so gloomy, but is there anybody who really believes that once Bush is gone things will suddenly be 'all right'?
Surely once the percentage of bots gets high enough (say if someone releases a good free poker bot for download) the bots will just balance each other out? If all the bad players who would play at the low tables replace themselves with bots there's little advantage to farming bad players.
If the bots become good enough then I suppose nobody will bother to play for real, but then if the whole field is bots there's not much money to be made off real people. I guess this would kill online poker, since nobody would play for real (too many bots) and nobody would bother botting (bots can't be easily beaten like bad players).
Of course, then the good players will have to come up with bot-beating bots and find the tables with lots of bots...
Did anybody else notice how strange Thompson's comments on statistics are? e.g.
"...a Gallop poll found 71 percent of all U.S teenage boys who played Vice City were twice as likely to have been engaged in an act of violence."
What? 71 percent were twice as likely? Is this some kind of maths problem?
And:
"Well, let's look at deaths in and around schools. In 2004, there were 48 in number. In 2003, there were 16. In 2002, there were 17. Yes, the death rate in which murderous actions have taken place has gone down, but there are other factors such as the shortening of ambulance response time, better medical techniques, and so forth."
I really don't think 3 years of statistics where the first two years are the same gives much of an idea of the trend. Look at say 20 years, so that we could at least compare the statistics for times before violent games were common. Violent games existed way before 2002.
Slashdot Mirror
These stories always say it was Einstein's great blunder and it has been vindicated, but it really hasn't. The reason Einstein put it in was that he couldn't find any solutions to his equations that resulted in a static universe. (At the time, Hubble's revolutionary results on the recession of distant galaxies had not been completed, so it was thought the universe must be static) All of his model universes were expanding or contracting. So he added the constant to balance out the contraction in his favoured model (which was also closed, another historical assumption in cosmology that has been disposed of).
OK, but the cosmological constant we see now is being used to explain the _acceleration_ of the universe, nothing like what Einstein put the constant in for. His blunder wasn't really the constant, it was the assumption that the universe was static, which turned out to be totally wrong.
But you have to admire Einstein - out of pure thought and mathematics he produced a theory which is still held up as a foundation of modern physics, even though practically every cosmological observation was made years after he published it (and all the observations have supported the theory to great accuracy). Compare this to, say, quantum mechanics, where many theorists struggled for decades to explain observations that had already been made, and Einstein's one-man theory is truly impressive.
It is based on the diameter of the primary mirror (~10m for SALT). The equal is the prototype which SALT is based on, the HET in Texas (I think). Resolution depends on diameter so it would also have the best resolution, but the Earth's atmosphere tends to distort things too much. This is why the Hubble Space Telescope (which is a mere 2.4M) is so valuable - no atmospheric disturbance.
However, having a giant mirror means that the telescope can observe faint objects in less time than anything in space at the moment, so can take much higher resolution spectra.
The actual telescope can't use the whole mirror at once because of the design. The telescope only moves in azimuth, which saves a huge amount of cost but means that only a small part of the mirror is used at any one time. As the target rotates around the sky the area on the telescope moves across the mirror to allow longer exposures.
SALT also has very high sensitivity to short wavelengths (blue/UV) which is probably the best of any large telescope, or at least close.
Feynman also once bet (but only a nickel or something) against Fred Hoyle, whose book claimed that a space traveller flying out along the axis of the Milky Way at close to the speed of light would see a fishbowl-like effect with a red rim and a blue bowl.
Turns out Feynman was wrong (!). It's a fun problem if you want to try it : ) Also goes to show that even the brilliant intuition of Feynman can be fooled by the wierdness of relativity.
Another example is a bet of a case of whiskey by Brian Schmidt and Ken Freeman I think (two astronomers working in Australia) about the value of the Hubble constant being greater than or less than 70 km per sec per megaparsec. Unfortunately the uncertainty bars were still to big after the time limit of the bet expired.
Because of relativity itself light always travels at the same speed for everyone - there is no way to slow it down to rest and have it turn into mass because no matter how fast we go we can't catch up to light. If, for example, we are travelling at 99% of the speed of light and as we go past someone they shoot some photons in front of us, they still speed ahead of us at the speed of light.
On the other hand, because of Einstein's later General Relativity we know that photons act as if they have mass when they are affected by or producing gravity. Light is deflected by gravitational fields around stars for example, and the combined energy of the photons in the universe was a major part of the early universe's mass/energy. (Now the radiation is too spread out to have much of an effect)
One of the most fundamental things in relativity is the idea that only massive particles/objects can be brought to rest. (Note that the idea that mass somehow increases as you speed something up is very out of date now. Physicists just use a fixed, so-called rest mass for particles at any speed. It is really the momentum and total energy that increase vastly as you approach the speed of light)
http://www.m-w.com/info/favorite.htm
It's number 4! You are just a jealous lingweenie!
: P
Also, by measuring the expansion rate of the universe over a very long time (ie. billions of years), and making observations of the Cosmic Microwave Backgound (CMB, the left over radiation from around 300000 years after the Big Bang) we can calculate the amount of matter it must contain. Then from models of the Big Bang and the CMB observations we can also find the amount of 'normal' matter (ie atoms), which comes to about 4% of the so called 'critical density', which is the amount of matter/energy required to have the universe be spatially flat (expands forever but tends toward zero expansion rate as time goes to infinity)
Since the amount of matter is measured to be around 25% this means dark matter must be around 20% of the critical density.
Incidentally, this also means that 75% of the energy/matter in the universe is 'dark energy', since the cosmic microwave background indicates the universe is almost exactly flat.
However, the importance of each constituent changes over time because essentially the dark energy is proportional to the size of the universe and when it was much smaller the matter was more concentrated so it had a far greater influence. Therefore for studies of the early evolution of the universe the dark energy is unimportant, and since dark matter is most of the total matter the models can just use dark matter alone. At present, however, the dark energy appears to be causing an acceleration of the expansion rate, which is seen using distant supernovae. This is how the 75% figure is worked out.
NB: Nobody can explain what the dark matter or dark energy is right now! This is by far the most important problem in Cosmology, and there are many , many competing theories.
It may be the worst time in history right now, but do you honestly expect things to be better in say, 5 years time? Will the Senate quit their corporate sponsorship? Will the Senate be less pro-buisiness? Will the gap between rich and poor get smaller?
And are Democratic Senators any less in the pocket of buisiness?
Sorry to be so gloomy, but is there anybody who really believes that once Bush is gone things will suddenly be 'all right'?
Are they going to use it for weapons in space?!?!
"Officials denied that any of the classified missions would involve nuclear arms, satellites or weapons in space.."
Oh, good.
"..but rather would power 'secret espionage devices"
Man, is that reassuring.
How is it a good thing that it will be used for secret espionage rather than space warfare again?
I use this mouse with X and have it set up so that 'scroll left' = middle click. Works fine! You just need to have
Option "Protocol" "IMPS/2"
Option "ZAxisMapping" "4 5"
in your xorg.conf file.
Scroll right however, does nothing at the moment, but it does register in xev as button4.
Surely once the percentage of bots gets high enough (say if someone releases a good free poker bot for download) the bots will just balance each other out? If all the bad players who would play at the low tables replace themselves with bots there's little advantage to farming bad players.
If the bots become good enough then I suppose nobody will bother to play for real, but then if the whole field is bots there's not much money to be made off real people. I guess this would kill online poker, since nobody would play for real (too many bots) and nobody would bother botting (bots can't be easily beaten like bad players).
Of course, then the good players will have to come up with bot-beating bots and find the tables with lots of bots...
Did anybody else notice how strange Thompson's comments on statistics are? e.g.
"...a Gallop poll found 71 percent of all U.S teenage boys who played Vice City were twice as likely to have been engaged in an act of violence."
What? 71 percent were twice as likely? Is this some kind of maths problem?
And:
"Well, let's look at deaths in and around schools. In 2004, there were 48 in number. In 2003, there were 16. In 2002, there were 17. Yes, the death rate in which murderous actions have taken place has gone down, but there are other factors such as the shortening of ambulance response time, better medical techniques, and so forth."
I really don't think 3 years of statistics where the first two years are the same gives much of an idea of the trend. Look at say 20 years, so that we could at least compare the statistics for times before violent games were common. Violent games existed way before 2002.
Giles