What they mean to say is that this seems to be the lowest mass planet found orbiting a main-sequence star.
It's also annoying that the press release quotes the radius of the planet (which cannot be measured, and is only an approximation based on guesses at density), when what they actually measured is the mass. Planetary densities vary widely; they have no idea what the radius is.
Nope. That's entirely speculation. We do not know the transverse velocity of the Andromeda galaxy, only the velocity along the line of sight. No way to tell if it's going to hit or not.
Actually, that's only true of a non-rotating (or Kerr) singularity. Yeah, I thought about mentioning that, and decided what I was writing was getting a bit complicated already
All natural black holes will be rotating (the black hole maintains the rotational momentum of the pre-collapse mass).
Well, maybe. Actually, rotating black holes radiate away angular momentum, and they also preferentially eat material that reduces their angular momentum, so it's an open question as to whether real black holes will be rotating. Probably, because the accretion disk is likely to be rotating, and it swallows up the accretion disk and gains the momentum from it, but I'm not sure you can necessarily say that all natural black holes will rotate.
In a rotating black hole, the singularity is actually a ring (or torus). Inside that ring/torus, there is a tear in space.
It was this tear that lead, if I recall, to the original conjectures of a white hole, and the Einstein-Rosen bridge.
Actually, the Einstein-Rosen bridge comes from the maximum analytical extension of the Flamm embedding, way predating the Kerr solution. (It's a very trivial embedding, z = sqrt(r). The extension is z = plus or minus sqrt(r).) Turns out that the extended Flamm embedding is misleading, and a Schwartzschild black hole isn't a wormhole after all. But that wasn't obvious.
Actually, the Schwarzchild solution does have a well-defined radius.
No, actually it doesn't. What is usually called the Schwartzschild "radius" is not actually a radius by the definition of the word, "distance to the center".
In fact, the problem is that it has many well-defined radii, depending on what you mean by the term (as you point out, this comes about because of the non-Euclidean nature of the geometry). The commonly quoted "Schwarzschild radius" r = 2GM/c^2 is obtained by taking the area of the horizon and figuring out which "r" you would have to plug into A = 4 pi r^2 [true for a flat space sphere] to get the right result.
Exactly. You can calculate the area (which is well defined) and divide it by 4 pi, and you are free to call that the radius if you like. Or, equivalently, divide the circumference by two pi. But you can't measure the distance to the center.
Taking the circumference and dividing by 2 pi would achieve the same result. However, it is quite possible to figure out the proper distance between the horizon and the singularity by measuring the distance an infalling observer would travel. This distance is finite.
Finite... and timelike. It would be a little like trying to define the radius of a circle if you're standing on the circumference, and the center is next Tuesday at noon.
A problem can occur if you try and use constant time slices, using the "natural" time coordinate as defined by an observer far from the black hole. This gives silly results, but that is only because of badly behaved coordinates.
Within the event horizon, any choice of coordinates is rather badly behaved, because there is no well-behaved stationary coordinate system.
I thought that Black Holes had no dimensions, but this one is several miles across. Where have I gone wrong?
A black hole, conventionally, consists of an event horizon surrounding a region of space from which you can't send information to the external world. This region of space is not a point, it has a well-defined circumference. (Because of the non-euclidean nature of general relativity, it doesn't actually have a well-defined radius (since you can't measure across the middle!) but people usually just consider the radius as if it were defined as the circumference divided by 2 pi, and don't worry about the fact that you can't actually measure it.)
At the center of the black hole is, according to general relativity, a point singularity, which indeed has no dimensions.
Would you consider including in the rating calculations the number of provably false statements made in support of the position or in attacking the opposing position?
No. First, the concept "provably false" turns out to usually be a viewpoint-dependent opinion. It is, in fact, astonishing how subjective that nominally objective statement is. (And if you don't think so, then I'd say you don't spend much time reading the opinions of people who disagree with you.)
Second, though, is that this is a different concept. It is interesting to pointing out when media print statements that are false, but that's a different king of thing from looking at their viewpoint bias.
You've been watching too much sci-fi...It's unlikely that something from such a wildly different evolutionary line would even be infectious to us. It's still pretty rare that diseases jump species here and everything on Earth is pretty closely related, genetically speaking.
Don't bother with that-- if Martian organisms are halophilic, they could not survive in a salt concentration as low as that in our bloodstream, or our oceans; they would literally fall apart.
...and if they're not halophilic, they wouldn't survive on Mars.
Salt on Mars has been a topic of interest for a while-- I wrote about the implications of Martian salt for Astrobiology a couple of years back, in an article in Astrobiology
Yow-- unbelievable as this may seem, this does seem to be true; a dozen other sites are reporting the same news, including the Wall Street Journal and the Washington Post, among others.
What in the world are they thinking? This seems to be a pretty flagrant abuse of power.
From the article, "MAC's exists so that not just anyone, for example, can look at your passport file without permission..."
Whaaaa?? Isn't that what just happened to the presidential candidates?
Yes, that's why he picked that particular example.
In light physics, temperature and color temperature are the same thing.
Correction, for a blackbody, in physics, temperature and color temperature are the same thing.
For an object which is not emitting as a blackbody, "color temperature" means, basically, the temperature that a blackbody would have to be at in order to emit the same color of light, where "color of light" has mostly a lot to do with physics of perception, and not physics of light. For an object that's not a blackbody, "color temperature" is not the same as temperature.
Additionally, if it really generated that much heat, it couldn't possibly be as efficient as even the worst incandescents.
To the contrary. The eye's range of sensitivity is tuned to the solar spectrum, emitted at a blackbody temperature just a bit below 6000 K. A bulb is most efficient if it emits light in the spectrum that the eye is sensitive to, and not in, say the infrared spectrum. So a bulb emitting blackbody spectrum becomes more efficient as the emission temperature goes up, and peaks in efficiency at around 6000.
Incandescent bulbs are not inefficient because they are too hot-- they are inefficient because they are not hot enough. They run somewhere about 2500 or 3000, and hence most of the light is emitted in the infrared, not the visible.
As it happens, i did that calculation. Roughly, my numbers suggest that the mercury contained in CF bulbs is roughly equal to
the mercury NOT emitted into the environment by burning coal, since less coal
is burned to support a CF bulb. So in terms of mercury in the environment,
CF bulbs aren't actually worse than what they're replacing; they're simply not
better.
In 2005, coal-burning electric plants emitted 45 tons (=4.5E7 grams) of mercury
in the US. That year the electric power production in the US was just over
4 billion Megawatt hours (4E12 kW-hr), so the emission is 1.1E-5 grams = 11
micrograms per kilowatt hour.
A 60-watt bulb that is on for typically two hours per day uses 44 kW-hours,
so the emission of mercury due to such a bulb would be about 480 micrograms
per year; or roughly 5 milligrams per ten years.
A 60-watt (equivalent) CF lightbulb has (by EPA standards, "no more than") 6
mg of mercury in it. If it is 4 times as efficient as an incandescent, it emits
120 micrograms per year, or 1.2 milligrams in 10 years. So the difference in
mercury emissions is 3.6 milligrams in 10 years. So if the bulb lasts 17 years
or longer, it would emit less mercury than the CF bulb.
The expected life of a CF bulb is between 6000 hours and 15,000 hours (between
8 and 20 years, at 2 hours per year), so overall, if you credit the lifetime
figures, the mercury emission is roughly a wash.
The exact break even point depends on what fraction of the electrical power
where you live comes from coal, as well, and whether the coal plants have scrubbers.
(the numbers above are average for the US, where electricity is about 50% coal,
in 2005)
Whether it's break-even or not over the lifetime of the bulb does not depend
on how long you burn the bulb per day, except that CF bulbs last longer if you
burn them longer-- so if you leave your bulbs on all the time, you get longer
life from them.
(Unfortunately, I don't much credit these predicted lifetimes. The lifetime
of a CF bulb drops the more often you turn it on or off, and my guess is that
these lifetimes are for bulbs that are never turned off, not for typical household
conditions nor for ratty NEO power. It's also quoted for "brand name" bulbs,
not the cheapo ones you buy at the dollar store. If your CF bulb has an EnergyStar
rating, by law it's guaranteed for two years. So you should keep a logbook
of every time you replace a light bulb, so you can get your five dollars back,
and you can email the EnergyStar program at cfl@energystar.gov to tell them
about it.)
How can one transmit science to a polarized audience? It's easy. There are two obvious methods:
Transmit parallel-polarized science. As long as the polarization is in the same direction as society, there will be no loss.
Use diffuse science. Reflect it off of something first (like a non-polarizing issue) and allow the polarized society to absorb what they will. There will be less overall reception, but at least SOME science that is not polarized the same way they are will get through to them. The likelihood any given tidbit of science is of course inversely proportional to its alignment to them, but with enough science projected, they should get a measurable amount over the whole spectrum.
It's an amusing proposal, but the only part that gets past the polarizing screen will be the portion that's polarized in the direction of the recipient.
So, once again, the only science that actually gets through to people is the part that they already agree with...
Yes, I agree-- the movie was a movie, not a scientific presentation, and in many ways I think it has hurt the actual communication of the science of global warming, since it was more about the flashy visuals and talking points, and tended to gloss over the (very real) science behind the hype (although, even so, it did have a lot more science than the average documentary).
And that's the problem-- people think that the movie is the science. There really needs to be a version of the movie with all the footnotes added.
Those techniques are so 20th century that they creak.
Here in the 21st century, you can measure the speed of light directly, using a pulse generator, a fast LED, a PIN photodiode, and a decent oscilloscope.
The main point that scientists need to communicate is that the fact that the methodology of science consists of looking at the evidence and forming an opinion, rather than forming an opinion and the looking for the evidence. I'm not sure that "framing" helps this, in fact, if done ineptly it could do the opposite, framing scientific arguments in the form of "here's the answer we want, now let's look for evidence".
This quote, about how science is actually done, is one I put on my quotable quotes page. It's worth reminding people that the "eureak" model of science is a little bit simplistic.
"The work of real science is hard and often for long intervals frustrating...
"Keep in mind that new ideas are commonplace, and almost always wrong. Most
flashes of insight lead nowhere; statistically, they have a half-life of hours
or maybe days. Most experiments to follow up the surviving insights are tedious and consume
large amounts of time, only to yield negative or (worse!) ambiguous results.""
-Edward O. Wilson
"Scientists, Scholars, Knaves, and Fools," in American Scientist 86 (1998)
But, as has been pointed out by Michael White, journalism is more about a "good story" than about accuracy about how science is done.
Everyone keeps saying that a solution to the problem of potential voter fraud would be to open-source the code.... what guarantee does anyone have that the code they've published is the same as the code on the machines the day of the election? It would be absolutely trivial to cut out the naughty bits before publishing.
If the code on the machine is not the same as the publically released code, that in and of itself would be tampering with the machine. It is not necessarily easy, but nevertheless it is possible to verify that the compiled code on the machine is the same as the compiled version of the released source code. If they are not, then you have evidence of a crime-- you don't need to figure out what the code on the machine does, you only need to show that it's not the code that the voting commission purchased.
On the other hand, if the source code is not released for inspection, well, you don't have any way of knowing exactly what it does, or if there are back doors, or even just inadvertant bugs that result in errors. ("a 12-bit register for vote count seemed big enough at the time... who would have thought that more than 4095 people in one voting district would have wanted to vote for -XXX-?")
I fail to see why it is so difficult to create a reliable voting machine. It's an adder... computer have been doing this since they were first conceived.
Slashdot Mirror
A lot of good discussion can be found on this blog, including an analysis of why the patent should not be held valid.
Ah, good for Phil! I need to start checking him first.
What they mean to say is that this seems to be the lowest mass planet found orbiting a main-sequence star.
It's also annoying that the press release quotes the radius of the planet (which cannot be measured, and is only an approximation based on guesses at density), when what they actually measured is the mass. Planetary densities vary widely; they have no idea what the radius is.
Nope. That's entirely speculation. We do not know the transverse velocity of the Andromeda galaxy, only the velocity along the line of sight. No way to tell if it's going to hit or not.
1 Corinthians 6:7-10, Romans 1:26-27, and 1 Timothy 1:10.
Depends on your definitions. Those are the letters of Paul, which are not technically gospel; but are rather commentary on the gospel.
Uh, what does this have to do with the topic?
Well, maybe. Actually, rotating black holes radiate away angular momentum, and they also preferentially eat material that reduces their angular momentum, so it's an open question as to whether real black holes will be rotating. Probably, because the accretion disk is likely to be rotating, and it swallows up the accretion disk and gains the momentum from it, but I'm not sure you can necessarily say that all natural black holes will rotate.
In a rotating black hole, the singularity is actually a ring (or torus). Inside that ring/torus, there is a tear in space.It was this tear that lead, if I recall, to the original conjectures of a white hole, and the Einstein-Rosen bridge.
Actually, the Einstein-Rosen bridge comes from the maximum analytical extension of the Flamm embedding, way predating the Kerr solution. (It's a very trivial embedding, z = sqrt(r). The extension is z = plus or minus sqrt(r).) Turns out that the extended Flamm embedding is misleading, and a Schwartzschild black hole isn't a wormhole after all. But that wasn't obvious.
No, actually it doesn't. What is usually called the Schwartzschild "radius" is not actually a radius by the definition of the word, "distance to the center".
In fact, the problem is that it has many well-defined radii, depending on what you mean by the term (as you point out, this comes about because of the non-Euclidean nature of the geometry). The commonly quoted "Schwarzschild radius" r = 2GM/c^2 is obtained by taking the area of the horizon and figuring out which "r" you would have to plug into A = 4 pi r^2 [true for a flat space sphere] to get the right result.Exactly. You can calculate the area (which is well defined) and divide it by 4 pi, and you are free to call that the radius if you like. Or, equivalently, divide the circumference by two pi. But you can't measure the distance to the center.
Taking the circumference and dividing by 2 pi would achieve the same result. However, it is quite possible to figure out the proper distance between the horizon and the singularity by measuring the distance an infalling observer would travel. This distance is finite.Finite... and timelike. It would be a little like trying to define the radius of a circle if you're standing on the circumference, and the center is next Tuesday at noon.
A problem can occur if you try and use constant time slices, using the "natural" time coordinate as defined by an observer far from the black hole. This gives silly results, but that is only because of badly behaved coordinates.Within the event horizon, any choice of coordinates is rather badly behaved, because there is no well-behaved stationary coordinate system.
A black hole, conventionally, consists of an event horizon surrounding a region of space from which you can't send information to the external world. This region of space is not a point, it has a well-defined circumference. (Because of the non-euclidean nature of general relativity, it doesn't actually have a well-defined radius (since you can't measure across the middle!) but people usually just consider the radius as if it were defined as the circumference divided by 2 pi, and don't worry about the fact that you can't actually measure it.)
At the center of the black hole is, according to general relativity, a point singularity, which indeed has no dimensions.
No. First, the concept "provably false" turns out to usually be a viewpoint-dependent opinion. It is, in fact, astonishing how subjective that nominally objective statement is. (And if you don't think so, then I'd say you don't spend much time reading the opinions of people who disagree with you.)
Second, though, is that this is a different concept. It is interesting to pointing out when media print statements that are false, but that's a different king of thing from looking at their viewpoint bias.
Don't bother with that-- if Martian organisms are halophilic, they could not survive in a salt concentration as low as that in our bloodstream, or our oceans; they would literally fall apart.
...and if they're not halophilic, they wouldn't survive on Mars.
Yes.
Salt on Mars has been a topic of interest for a while-- I wrote about the implications of Martian salt for Astrobiology a couple of years back, in an article in Astrobiology
What in the world are they thinking? This seems to be a pretty flagrant abuse of power.
Yes, that's why he picked that particular example.
Correction, for a blackbody, in physics, temperature and color temperature are the same thing.
For an object which is not emitting as a blackbody, "color temperature" means, basically, the temperature that a blackbody would have to be at in order to emit the same color of light, where "color of light" has mostly a lot to do with physics of perception, and not physics of light. For an object that's not a blackbody, "color temperature" is not the same as temperature.
No.
To the contrary. The eye's range of sensitivity is tuned to the solar spectrum, emitted at a blackbody temperature just a bit below 6000 K. A bulb is most efficient if it emits light in the spectrum that the eye is sensitive to, and not in, say the infrared spectrum. So a bulb emitting blackbody spectrum becomes more efficient as the emission temperature goes up, and peaks in efficiency at around 6000.
Incandescent bulbs are not inefficient because they are too hot-- they are inefficient because they are not hot enough. They run somewhere about 2500 or 3000, and hence most of the light is emitted in the infrared, not the visible.
In 2005, coal-burning electric plants emitted 45 tons (=4.5E7 grams) of mercury in the US. That year the electric power production in the US was just over 4 billion Megawatt hours (4E12 kW-hr), so the emission is 1.1E-5 grams = 11 micrograms per kilowatt hour.
A 60-watt bulb that is on for typically two hours per day uses 44 kW-hours, so the emission of mercury due to such a bulb would be about 480 micrograms per year; or roughly 5 milligrams per ten years.
A 60-watt (equivalent) CF lightbulb has (by EPA standards, "no more than") 6 mg of mercury in it. If it is 4 times as efficient as an incandescent, it emits 120 micrograms per year, or 1.2 milligrams in 10 years. So the difference in mercury emissions is 3.6 milligrams in 10 years. So if the bulb lasts 17 years or longer, it would emit less mercury than the CF bulb.
The expected life of a CF bulb is between 6000 hours and 15,000 hours (between 8 and 20 years, at 2 hours per year), so overall, if you credit the lifetime figures, the mercury emission is roughly a wash.
The exact break even point depends on what fraction of the electrical power where you live comes from coal, as well, and whether the coal plants have scrubbers. (the numbers above are average for the US, where electricity is about 50% coal, in 2005)
Whether it's break-even or not over the lifetime of the bulb does not depend on how long you burn the bulb per day, except that CF bulbs last longer if you burn them longer-- so if you leave your bulbs on all the time, you get longer life from them.
(Unfortunately, I don't much credit these predicted lifetimes. The lifetime of a CF bulb drops the more often you turn it on or off, and my guess is that these lifetimes are for bulbs that are never turned off, not for typical household conditions nor for ratty NEO power. It's also quoted for "brand name" bulbs, not the cheapo ones you buy at the dollar store. If your CF bulb has an EnergyStar rating, by law it's guaranteed for two years. So you should keep a logbook of every time you replace a light bulb, so you can get your five dollars back, and you can email the EnergyStar program at cfl@energystar.gov to tell them about it.)
This reference goes through basically the same calculation.
It's an amusing proposal, but the only part that gets past the polarizing screen will be the portion that's polarized in the direction of the recipient.
So, once again, the only science that actually gets through to people is the part that they already agree with...
And that's the problem-- people think that the movie is the science. There really needs to be a version of the movie with all the footnotes added.
Here in the 21st century, you can measure the speed of light directly, using a pulse generator, a fast LED, a PIN photodiode, and a decent oscilloscope.
This quote, about how science is actually done, is one I put on my quotable quotes page. It's worth reminding people that the "eureak" model of science is a little bit simplistic.
"The work of real science is hard and often for long intervals frustrating...
"Keep in mind that new ideas are commonplace, and almost always wrong. Most flashes of insight lead nowhere; statistically, they have a half-life of hours or maybe days. Most experiments to follow up the surviving insights are tedious and consume large amounts of time, only to yield negative or (worse!) ambiguous results.""
-Edward O. Wilson
"Scientists, Scholars, Knaves, and Fools," in American Scientist 86 (1998)
But, as has been pointed out by Michael White, journalism is more about a "good story" than about accuracy about how science is done.
If the code on the machine is not the same as the publically released code, that in and of itself would be tampering with the machine. It is not necessarily easy, but nevertheless it is possible to verify that the compiled code on the machine is the same as the compiled version of the released source code. If they are not, then you have evidence of a crime-- you don't need to figure out what the code on the machine does, you only need to show that it's not the code that the voting commission purchased.
On the other hand, if the source code is not released for inspection, well, you don't have any way of knowing exactly what it does, or if there are back doors, or even just inadvertant bugs that result in errors. ("a 12-bit register for vote count seemed big enough at the time... who would have thought that more than 4095 people in one voting district would have wanted to vote for -XXX-?")
Or ARs technica
Exactly... if the software is really so simple, then, just why do the voting machine companies call it proprietary and refuse to let anybody inspect their code or their machines? Sequoia just threatened the state of New Jersey with a lawsuit if they let an outside lab access to a voting machine to test it after about 60 Sequoia voting machines across the state seemed to malfunction during the state's Feb. 5 primary.