actually agree on the numbers (at least the numbers they mention). The dude claiming 750 MW-hours per year gets that number by assuming a 20% difference ((74W- 59W)/74W = 0.203 ) between white and black screens and only counts CRT monitors. He never claims that this savings is true for LCD. What he does do is assume that CRTs account for 25% of all monitors.
The WSJ blogger asked the Energy Star folks who asked the Cadmus Group to do a quick test. They found between 5% and 20% power difference between black and white on CRTs and no difference on LCDs. This doesn't really contradict the first article's numbers. He even confirms the 25% of monitors being CRT number, or rather, he states that 3/4 are LCD.
The real point here is that 750 MW-hours per year is (in more simple units) 8.6 x 10^4 Watts which is the equivalent of roughly 1500 60 Watt light bulbs. So Google switching to black background is the approximate equivalent of turning off 1500 light bulbs worldwide. That's a very, very, very small number compared to the total number of 60 Watt bulbs in use all over the world. Furthermore, nearly 100% of all monitors will eventually (probably very soon) be LCD, rendering those 1500 light bulbs moot. Oh well.
A 3D virtual environment that is as accessible as the current Web could be a boon to distance learning via online courses, especially for subjects like science, engineering, architecture, etc. Virtual world apps like Second Life or OpenCroquet will allow instructors to produce virtual, interactive, 3D demonstrations, models and other teaching aids that can be used collaboratively by students that are physically distant from each other and the instructor.
While a real-world laboratory class experience is certainly preferable, simulations in virtual lab settings for education and training are safer and may be more accessible to students who are in remote locations or to students who are disabled in some way that makes a real lab course difficult or impossible for them to attend.
Having taught physics and astronomy classes, I have often wished for a 3D chalkboard on which to draw diagrams to describe, for instance, electron motion in a magnetic field, or the difference between lunar phases and eclipses, or 3+ body gravitational interactions. In a 3D virtual classroom, I could do that. That technology is here and I would like to see it become integrated with the Web so that it is easy and cheap to access and use.
I'll grant that we have a ways to go before we have very good input/output devices for interacting with a Stephenson-like Metaverse, but for now my monitor and mouse will do. The I/O tech will catch up eventually. VR "goggles" are morphing into VR "glasses" or better yet augmented reality glasses. And Nintendo may be on to something with the Wii controller! We'll have to wait and see.
Concerning the skepticism of a 3D Web that I have seen posted in this discussion so far, I don't think the 2D Web will disappear as it gives way to a 3D Metaverse, but I do think there is room and use for both. I imagine that they will be tightly integrated and eventaully thought of as one entity. The Web is already a virtual world of sorts and we teleport around that world whenever we click a link. I imagine a 3D Web will work similarly while much of the content will continue to be displayed as 2D words on a page. However, more and more useful (and useless) content will show up as 3D objects of one sort or another.
Delaying is as bad as cancelling in some cases. From the article:
"We're getting ready to fire all the people we've built up," said Dr. Beichman, who is the project scientist for the second of the two spacecraft missions, once scheduled for about 2020. Once those scientists have found other jobs, he said, they are not likely to come back.
Anyway, this is a matter or priorities. The current leadership has decided that manned space flight is a higher priority than earth and space science.
Good question! In this case, the h in Mpc/h does not mean "hour". It is a fudge factor for dealing with the uncertainty in our determination of the Hubble constant. In the astrophysics and cosmology literature you will often see the Hubble constant expressed as
H0 = 100h km/s/Mpc
where h is a dimensionless parameter between 0.5 and 1 (thus the Hubble constant is between 50 and 100 km/s/Mpc). The current estimated value of the Hubble constant is about 70 km/s/Mpc (h =.70), with an error of about 10%. One of the Hubble Space telescopes key missions was/is to determine the Hubble constant to high precision (10% doesn't seem that high precision but it is pretty darn good for cosmology).
Makes more sense... so they have tried to spot the ripples in the galxy distribution themselves?
Yes, that is correct. They are looking at the patterns in the distribution of galaxies. They are not detecting radio waves. They are infering accoustic waves (i.e. longitudinal "pressure" waves that propagated through the hot dense matter-radiation soup of the early universe) from the pattern left behind after matter and radiation decoupled. Pretty neat trick, really.
To find the frequency, don't you have to wait for at least half the frequency to know it?
You are partially correct. You need to see at least half of the wave to measure its wavelength. To get the frequency from the wavelength you generally need to know the speed of the wave.
How can they accurately extrapolate a length of 500MLY from about 1LY of data (if indeed they took that length of reading).
I think you are confusing lightyears and years. A lightyear is a unit of length. The astronomers here have measured a wavelength of 500 million lightyears. They didn't take a "lightyear" of data. I'm not sure what you even mean by that. The survey of galaxies they used had to cover a distance of more than 500 MLY in at least one direction.
Concerning how they actually found this wave and measured its wavelength, I have not yet seen a detailed journal article nor was I able to attend the AAS meeting where these results were presented, but I can take a guess:
First of all, they are looking at the pattern left over by those accoustic waves. Once the universe cooled enough for matter and radiation to decouple, the push-pull between gravity and radiation pressure disappeared (more or less) and these waves stopped progagating. All that is left are the wave patterns, essentially frozen into the large-scale structure of the universe. They are using the distribution of galaxies to track this structure.
Most likely, they did a 2D Fourier Transformation of a map of the galaxies created from one of the galaxy surveys mentioned in the article and found a statistically significant power at a wavenumber = 1/500 MLY. I'm sure there were other numerical gymnastics they had to perform to get there, but in essence it is just an FT. That is my guess, anyway.
Slashdot Mirror
actually agree on the numbers (at least the numbers they mention). The dude claiming 750 MW-hours per year gets that number by assuming a 20% difference ((74W- 59W)/74W = 0.203 ) between white and black screens and only counts CRT monitors. He never claims that this savings is true for LCD. What he does do is assume that CRTs account for 25% of all monitors.
The WSJ blogger asked the Energy Star folks who asked the Cadmus Group to do a quick test. They found between 5% and 20% power difference between black and white on CRTs and no difference on LCDs. This doesn't really contradict the first article's numbers. He even confirms the 25% of monitors being CRT number, or rather, he states that 3/4 are LCD.
The real point here is that 750 MW-hours per year is (in more simple units) 8.6 x 10^4 Watts which is the equivalent of roughly 1500 60 Watt light bulbs. So Google switching to black background is the approximate equivalent of turning off 1500 light bulbs worldwide. That's a very, very, very small number compared to the total number of 60 Watt bulbs in use all over the world. Furthermore, nearly 100% of all monitors will eventually (probably very soon) be LCD, rendering those 1500 light bulbs moot. Oh well.
Ok. Time to get back to work.
A 3D virtual environment that is as accessible as the current Web could be a boon to distance learning via online courses, especially for subjects like science, engineering, architecture, etc. Virtual world apps like Second Life or OpenCroquet will allow instructors to produce virtual, interactive, 3D demonstrations, models and other teaching aids that can be used collaboratively by students that are physically distant from each other and the instructor.
While a real-world laboratory class experience is certainly preferable, simulations in virtual lab settings for education and training are safer and may be more accessible to students who are in remote locations or to students who are disabled in some way that makes a real lab course difficult or impossible for them to attend.
Having taught physics and astronomy classes, I have often wished for a 3D chalkboard on which to draw diagrams to describe, for instance, electron motion in a magnetic field, or the difference between lunar phases and eclipses, or 3+ body gravitational interactions. In a 3D virtual classroom, I could do that. That technology is here and I would like to see it become integrated with the Web so that it is easy and cheap to access and use.
I'll grant that we have a ways to go before we have very good input/output devices for interacting with a Stephenson-like Metaverse, but for now my monitor and mouse will do. The I/O tech will catch up eventually. VR "goggles" are morphing into VR "glasses" or better yet augmented reality glasses. And Nintendo may be on to something with the Wii controller! We'll have to wait and see.
Concerning the skepticism of a 3D Web that I have seen posted in this discussion so far, I don't think the 2D Web will disappear as it gives way to a 3D Metaverse, but I do think there is room and use for both. I imagine that they will be tightly integrated and eventaully thought of as one entity. The Web is already a virtual world of sorts and we teleport around that world whenever we click a link. I imagine a 3D Web will work similarly while much of the content will continue to be displayed as 2D words on a page. However, more and more useful (and useless) content will show up as 3D objects of one sort or another.
Just my two cents.
"We're getting ready to fire all the people we've built up," said Dr. Beichman, who is the project scientist for the second of the two spacecraft missions, once scheduled for about 2020. Once those scientists have found other jobs, he said, they are not likely to come back.
Anyway, this is a matter or priorities. The current leadership has decided that manned space flight is a higher priority than earth and space science.
I miss Master of Magic! Veteran Hafling Slingers kicked ass!
Now /. users and the rest of humanity has to pay me to wipe their rear ends.
Then we'll all just start using the 3 sea shells!
Good question! In this case, the h in Mpc/h does not mean "hour". It is a fudge factor for dealing with the uncertainty in our determination of the Hubble constant. In the astrophysics and cosmology literature you will often see the Hubble constant expressed as
.70), with an error of about 10%. One of the Hubble Space telescopes key missions was/is to determine the Hubble constant to high precision (10% doesn't seem that high precision but it is pretty darn good for cosmology).
H0 = 100h km/s/Mpc
where h is a dimensionless parameter between 0.5 and 1 (thus the Hubble constant is between 50 and 100 km/s/Mpc). The current estimated value of the Hubble constant is about 70 km/s/Mpc (h =
Yes, that is correct. They are looking at the patterns in the distribution of galaxies. They are not detecting radio waves. They are infering accoustic waves (i.e. longitudinal "pressure" waves that propagated through the hot dense matter-radiation soup of the early universe) from the pattern left behind after matter and radiation decoupled. Pretty neat trick, really.
You are partially correct. You need to see at least half of the wave to measure its wavelength. To get the frequency from the wavelength you generally need to know the speed of the wave.
How can they accurately extrapolate a length of 500MLY from about 1LY of data (if indeed they took that length of reading).
I think you are confusing lightyears and years. A lightyear is a unit of length. The astronomers here have measured a wavelength of 500 million lightyears. They didn't take a "lightyear" of data. I'm not sure what you even mean by that. The survey of galaxies they used had to cover a distance of more than 500 MLY in at least one direction. Concerning how they actually found this wave and measured its wavelength, I have not yet seen a detailed journal article nor was I able to attend the AAS meeting where these results were presented, but I can take a guess:
First of all, they are looking at the pattern left over by those accoustic waves. Once the universe cooled enough for matter and radiation to decouple, the push-pull between gravity and radiation pressure disappeared (more or less) and these waves stopped progagating. All that is left are the wave patterns, essentially frozen into the large-scale structure of the universe. They are using the distribution of galaxies to track this structure.
Most likely, they did a 2D Fourier Transformation of a map of the galaxies created from one of the galaxy surveys mentioned in the article and found a statistically significant power at a wavenumber = 1/500 MLY. I'm sure there were other numerical gymnastics they had to perform to get there, but in essence it is just an FT. That is my guess, anyway.