The windows are supposed to break like that. The windows break into thousands of surprisingly unsharp pieces. It's for the opposite case of getting out of the store in case of emergency or just in general making breaking a window not as potentially lethal.
That's exactly what we will do. This hypothesis will be quantified into making predictions about what we will see from supernovae and gamma-ray bursts (and perhaps other events). We will then plan and conduct observations of these events and see if the predictions of this hypothesis are consistent with the new data.
A lot of interesting ideas like this come out but then stall for a while as people try translate qualitative ideas into quantitative predictions. Once that happens we can go out and test them.
The expansion rate of the Universe at the present time is called the Hubble constant. Astronomers more generally refer to the Hubble parameter to describe the expansion rate as a function of cosmic time. We have known that the Hubble parameter changes with time for at least 60 years, but, as you note, we've only known that the rate is currently accelerating for the past decade.
Why would they need to verify your identities? When someone is born they can have whatever name their parents choose to give them. Since the mother gave birth in the hospital, the relationship of mother to baby was not in question and she was free to name the child whatever she wanted. The other details on the birth certificate pertaining to the child are things the hospital knows.
I assume you're curious that under the lines for mother and father they just took whatever you said and were surprised at that, but in most applications that's not really important. It may be later if your daughter wants to claim Australian citizenship by right of parentage, but mostly birth certificates are used to certify that someone was born in a particular place on a particular date. The hospital had no doubts on those points.
A mathematician should not necessarily have pi memorized beyond any particular number of decimal places. However, she should be able to tell you at least 5 different ways to calculate pi and what each of the different techniques reveals about pi, transcendental numbers, series, convergence, geometry, etc.
That's exactly what I've been wondering about this technology. If the ground-based power density is less than that of the Sun, how is this more efficient than just having solar collectors on the ground?
If the answer is, ah, because it's all in a narrow frequency range that's easily convertible, then you're actually at much higher than the power density of the Sun in the frequency range and you need to discuss what absorbs well at the frequency. I.e., the gentle 25% of the midday sun number is somewhat misleading.
We already know that that frequency is not that of water, because you would have to be an idiot to try to microwave all of the water in the atmosphere. Presumably it's in a relatively transparent microwave window in the atmosphere.
"It is not as useful or profitable for a telco to do the same, because "
they are not legally on the hook. Thanks to some consumer-friendly legislation passed a while back, the credit card companies are specifically liable for fraudulent transactions above a $50 limit. The phone companies are not.
Figuring out whether or not the marginal cost to the phone company was comparable to $52k (they're probably paying some other company to call Bulgaria) is complicated. But I'll agree that it's likely much less, whereas the marginal cost to the CC company is the numeric amount. But really I think the liability protection has made the biggest difference in how attentive CC companies are to these things. Other practices aside, this is something that most CC companies do very well in striking a balance between usability and minimizing fraud.
IAAA and I completely agree with Dijkstra. The academic field of Computer Science is not about computers or being a kick-assembly coder. Just as English is not about composition, and Math is not about arithmetic. Part of the confusion in these discussions is that most of the people Computer Science departments tend to graduate go on to be software engineers and find themselves on/.
FWIW, I'm an astronomer who spends most of his days writing code to analyze data taken by large complicated telescopes whose operation I understand but which I should never be asked to fix.
It's essentially focused to infinity, which amounts to everything more than perhaps a few hundred miles away (I'm making that last number up a bit; it might be closer).
It has 10 micron pixels that cover the focal plane at 0.25 arcseconds per pixel for a total field of view of over 7 square degrees.
left-click to define the start of a region
[let go of the button]
right-click to define the end of a region
Now your region is selected. Paste at will. This is much more accurate then left-click and holding down because the holding-down way tends to mess with how well you can point the mouse. It saddens me whenever I use a terminal program that steals the right-click button for something else because it's clear that the developers didn't know you could do this.
Yes exactly. For room-temperature (300 degrees K, 27 degrees C), the blackbody radiation peaks around 9-10 microns. IR in the context of CCD cameras is around 1 micron, so it's not that important to be colder than room temperature (although it's still helpful). If you want to observe at 10 microns then you would like to be down at perhaps 100 K (conveniently liquid nitrogen is at 77 K) and down to 3 K (liquid helium refrigeration) if you want to get out to 500 microns.
See
http://spectralcalc.com/blackbody_calculator/blackbody.php
for an easy way to visualize the spectrum of a blackbody at different temperatures (they occasionally pop up ads for something or other but it is a good visualization aid for this sort of stuff). Set the wavelength range from a lower limit of 1 micron (um) to 1000 um to display the range we're talking about here.
Transparent in IR is relatively easy (although not necessarily all the way out to 500 microns). Not emitting in the IR is hard. You have to be very cold (3 degrees Kelvin would be good). Much colder then you'd like the skin of the plane to be.
Obviously the air is not that cold, but it's much thinner and so doesn't emit nearly as much as a solid sheet of whatever transparent material you could think of.
I think by "too expensive" he means that there are instruments that work 80% of the time but need to be (kicked | disassembled | mucked around with) occasionally. Making these instruments 10x lighter, 98% reliable, and with no need for outside intervention might be one to two orders of magnitude more expensive to develop for a spacecraft that you never get to touch again (or that you have to pay ~$500 million for each repair). So an instrument that was $10 million is now several hundred million dollars. Even for a spacecraft that's real money.
When people put stuff up in space you want to be conservative. So spacecraft are not good platforms for the latest and greatest instruments and new ideas. Part of the idea of an observatory that returns to the ground a lot is that you can try out new instruments much more easily and much more cheaply. In the case of the infrared it's important enough to get above the water vapor that it's worth making a flying observatory.
Vibration transferred from the plane is relatively straightforward to solve (although it can expensive to do it to tolerance). The biggest challenge that caused the most delay (years) for SOFIA was the layer of air that was happy to be going around the side of the plane and then suddenly sees a 3m gap in the side of the plane. This led to a significant amount of turbulence and both shaking of the telescope and degradation of the "seeing" (the sharpness of images through the atmosphere and optics; in this case the very local atmosphere). Significant redesign and careful consideration of the exact shape, baffling, etc. of the hold and telescope mount was necessary to overcome this problem.
It has a mirror that's more than two-and-a-half times larger, with correspondingly better resolution and sensitivity, and instrumentation that's several generations more advanced than Kuiper. Also, notably it will be flying and observing in the next decade and Kuiper hasn't flown since 1995. Science continues and new questions arise every day that need new observations to answer them.
The related political angle to the technical sharing of fast Javascript is to keep MS contained. Chrome doesn't have to be adopted. It's just there in the wings as a lurking threat to MS attempts to control the web. If it's ever necessary Google can move in strong and get Chrome fully developed. In the meantime, as you say, they're mostly hoping that IE and Firefox will speed of their Javascript implementations to allow the AJAX-type applications to continue to take over the web. I think they're otherwise worried that MS might succeed in this through some proprietary not-quite-compatible MS interface that will then lock Google out.
The detector surface is indeed effectively curved. It's made up of a large number of CCDs which will each be tangent to the focal surface at their location.
No. Dark matter is not really related to the darkness of the night sky. Dark matter is so named because it doesn't interact with light one way or the other. It doesn't absorb light, it doesn't emit light, so it ends up being separate from the question.
But the question of why is the night sky dark is sometimes known as Olbers' Paradox and has been used as one suggestion that the Universe is finite.
It's actually a fascinating example that information theory and compression really are true. The calibration images such as bias images (a readout of the CCD with no effective exposure time) or dark images (a readout of the CCD with the shutter closed but with an exposure time like those of the actual sky observations) indeed contain little information and so compresses by factors of 4-5 with straightforward things like gzip. Regular images of the sky compress by approximately a factor of 2.
Yes. I will definitely agree that there is strong indirect evidence for the first inflationary period lasting fractions of a second. In between then and 5 billion years ago, there is no clear evidence for any suspiciously accelerated or decelerated phase. But, of course, part of the entire challenge of determining the nature of dark energy is to determine if there perhaps was indeed some variation that our current techniques haven't yet been sensitive to. This is the billion-dollar question.
Slashdot Mirror
Yes, they are concerned. The stores are continual advertisements. Marketing would be horrified if they looked barricaded and unfriendly after hours.
The windows are supposed to break like that. The windows break into thousands of surprisingly unsharp pieces. It's for the opposite case of getting out of the store in case of emergency or just in general making breaking a window not as potentially lethal.
Just because they say it doesn't mean it's true or legally enforceable.
That's exactly what we will do. This hypothesis will be quantified into making predictions about what we will see from supernovae and gamma-ray bursts (and perhaps other events). We will then plan and conduct observations of these events and see if the predictions of this hypothesis are consistent with the new data. A lot of interesting ideas like this come out but then stall for a while as people try translate qualitative ideas into quantitative predictions. Once that happens we can go out and test them.
The expansion rate of the Universe at the present time is called the Hubble constant. Astronomers more generally refer to the Hubble parameter to describe the expansion rate as a function of cosmic time. We have known that the Hubble parameter changes with time for at least 60 years, but, as you note, we've only known that the rate is currently accelerating for the past decade.
Why would they need to verify your identities? When someone is born they can have whatever name their parents choose to give them. Since the mother gave birth in the hospital, the relationship of mother to baby was not in question and she was free to name the child whatever she wanted. The other details on the birth certificate pertaining to the child are things the hospital knows. I assume you're curious that under the lines for mother and father they just took whatever you said and were surprised at that, but in most applications that's not really important. It may be later if your daughter wants to claim Australian citizenship by right of parentage, but mostly birth certificates are used to certify that someone was born in a particular place on a particular date. The hospital had no doubts on those points.
A mathematician should not necessarily have pi memorized beyond any particular number of decimal places. However, she should be able to tell you at least 5 different ways to calculate pi and what each of the different techniques reveals about pi, transcendental numbers, series, convergence, geometry, etc.
This application would use almost certainly use a different frequency then power transfer to the ground.
That's exactly what I've been wondering about this technology. If the ground-based power density is less than that of the Sun, how is this more efficient than just having solar collectors on the ground? If the answer is, ah, because it's all in a narrow frequency range that's easily convertible, then you're actually at much higher than the power density of the Sun in the frequency range and you need to discuss what absorbs well at the frequency. I.e., the gentle 25% of the midday sun number is somewhat misleading. We already know that that frequency is not that of water, because you would have to be an idiot to try to microwave all of the water in the atmosphere. Presumably it's in a relatively transparent microwave window in the atmosphere.
"It is not as useful or profitable for a telco to do the same, because " they are not legally on the hook. Thanks to some consumer-friendly legislation passed a while back, the credit card companies are specifically liable for fraudulent transactions above a $50 limit. The phone companies are not. Figuring out whether or not the marginal cost to the phone company was comparable to $52k (they're probably paying some other company to call Bulgaria) is complicated. But I'll agree that it's likely much less, whereas the marginal cost to the CC company is the numeric amount. But really I think the liability protection has made the biggest difference in how attentive CC companies are to these things. Other practices aside, this is something that most CC companies do very well in striking a balance between usability and minimizing fraud.
FWIW, I'm an astronomer who spends most of his days writing code to analyze data taken by large complicated telescopes whose operation I understand but which I should never be asked to fix.
It's essentially focused to infinity, which amounts to everything more than perhaps a few hundred miles away (I'm making that last number up a bit; it might be closer). It has 10 micron pixels that cover the focal plane at 0.25 arcseconds per pixel for a total field of view of over 7 square degrees.
In well-designed terminals viewers such as xterm:
left-click to define the start of a region
[let go of the button]
right-click to define the end of a region
Now your region is selected. Paste at will. This is much more accurate then left-click and holding down because the holding-down way tends to mess with how well you can point the mouse. It saddens me whenever I use a terminal program that steals the right-click button for something else because it's clear that the developers didn't know you could do this.
'--' terminates option processing for most well-behaved utilities.
Yes exactly. For room-temperature (300 degrees K, 27 degrees C), the blackbody radiation peaks around 9-10 microns. IR in the context of CCD cameras is around 1 micron, so it's not that important to be colder than room temperature (although it's still helpful). If you want to observe at 10 microns then you would like to be down at perhaps 100 K (conveniently liquid nitrogen is at 77 K) and down to 3 K (liquid helium refrigeration) if you want to get out to 500 microns. See http://spectralcalc.com/blackbody_calculator/blackbody.php for an easy way to visualize the spectrum of a blackbody at different temperatures (they occasionally pop up ads for something or other but it is a good visualization aid for this sort of stuff). Set the wavelength range from a lower limit of 1 micron (um) to 1000 um to display the range we're talking about here.
Transparent in IR is relatively easy (although not necessarily all the way out to 500 microns). Not emitting in the IR is hard. You have to be very cold (3 degrees Kelvin would be good). Much colder then you'd like the skin of the plane to be. Obviously the air is not that cold, but it's much thinner and so doesn't emit nearly as much as a solid sheet of whatever transparent material you could think of.
I think by "too expensive" he means that there are instruments that work 80% of the time but need to be (kicked | disassembled | mucked around with) occasionally. Making these instruments 10x lighter, 98% reliable, and with no need for outside intervention might be one to two orders of magnitude more expensive to develop for a spacecraft that you never get to touch again (or that you have to pay ~$500 million for each repair). So an instrument that was $10 million is now several hundred million dollars. Even for a spacecraft that's real money. When people put stuff up in space you want to be conservative. So spacecraft are not good platforms for the latest and greatest instruments and new ideas. Part of the idea of an observatory that returns to the ground a lot is that you can try out new instruments much more easily and much more cheaply. In the case of the infrared it's important enough to get above the water vapor that it's worth making a flying observatory.
Vibration transferred from the plane is relatively straightforward to solve (although it can expensive to do it to tolerance). The biggest challenge that caused the most delay (years) for SOFIA was the layer of air that was happy to be going around the side of the plane and then suddenly sees a 3m gap in the side of the plane. This led to a significant amount of turbulence and both shaking of the telescope and degradation of the "seeing" (the sharpness of images through the atmosphere and optics; in this case the very local atmosphere). Significant redesign and careful consideration of the exact shape, baffling, etc. of the hold and telescope mount was necessary to overcome this problem.
It has a mirror that's more than two-and-a-half times larger, with correspondingly better resolution and sensitivity, and instrumentation that's several generations more advanced than Kuiper. Also, notably it will be flying and observing in the next decade and Kuiper hasn't flown since 1995. Science continues and new questions arise every day that need new observations to answer them.
The related political angle to the technical sharing of fast Javascript is to keep MS contained. Chrome doesn't have to be adopted. It's just there in the wings as a lurking threat to MS attempts to control the web. If it's ever necessary Google can move in strong and get Chrome fully developed. In the meantime, as you say, they're mostly hoping that IE and Firefox will speed of their Javascript implementations to allow the AJAX-type applications to continue to take over the web. I think they're otherwise worried that MS might succeed in this through some proprietary not-quite-compatible MS interface that will then lock Google out.
The detector surface is indeed effectively curved. It's made up of a large number of CCDs which will each be tangent to the focal surface at their location.
No. Dark matter is not really related to the darkness of the night sky. Dark matter is so named because it doesn't interact with light one way or the other. It doesn't absorb light, it doesn't emit light, so it ends up being separate from the question. But the question of why is the night sky dark is sometimes known as Olbers' Paradox and has been used as one suggestion that the Universe is finite.
It's actually a fascinating example that information theory and compression really are true. The calibration images such as bias images (a readout of the CCD with no effective exposure time) or dark images (a readout of the CCD with the shutter closed but with an exposure time like those of the actual sky observations) indeed contain little information and so compresses by factors of 4-5 with straightforward things like gzip. Regular images of the sky compress by approximately a factor of 2.
They still stored all of the raw data, they just provided the reduced data products as a convenience to the astronomers.
Yes. I will definitely agree that there is strong indirect evidence for the first inflationary period lasting fractions of a second. In between then and 5 billion years ago, there is no clear evidence for any suspiciously accelerated or decelerated phase. But, of course, part of the entire challenge of determining the nature of dark energy is to determine if there perhaps was indeed some variation that our current techniques haven't yet been sensitive to. This is the billion-dollar question.