Gah, I missed the fact that < gets consumed by Slashdot's formatting. Everywhere that there's an "E0" in the last post, assume that it's "E<0", please.:-)
There's only one energy here. You are, I think, confusing energy with momentum. These are very different quantities.
Look, here's the energy of two gravitationally interacting bodies:
E = 1/2 (m1 v1^2 + m2 v2^2) - G m1 m1/r
For gravitationally bound bodies (i.e., in orbit), E0. (E=0 basically never happens for statistical reasons.)
Now, gravitation is a conservative force (never mind how you prove that for now), so E does not change during an interaction. v1 and v2 might increases as r decreases, by E does not change.
So if you start unbound (E>0), you cannot get E0 unless you dissipate energy. The gravity of the two bodies cannot change their mutual binding energy, so you need some other process.
Momentum is not energy. They are separate quantities and are conserved separately. The mass of the star is, as I stated earlier, irrelevant. When you have two bodies, the bind energy DOES NOT CHANGE during an interaction without some other dissipation. Gravity is a conservative force.
Look, I appreciate that you're throwing ideas out there, but this is pretty basic physics that we have a good handle on. If you don't believe me (which is fine!), look some of this stuff up for yourself.
Also, for the record, the star is less massive than the pulsar: the diagram of the orbits that I saw made it pretty clear that the star has the larger orbit.
You miss the point. They cannot be in orbit if they started out not in orbit UNLESS there is energy lost during the capturing. This is basic physics stemming for binding energies.
With planets, you can dissipate energy this with atmospheric drag, firing rockets (if you're a spacecraft), or three-body capture*. Only the last of these works with stars, and that's a dubious proposition since the millisecond pulsar would probably have been pretty close to its partner before the capture making it hard to strip during the encounter.
* In the interest of honesty, tides and gravity waves might do it, too, but in practice, their timescale for action is much too long to assist a capture.
What the heck are you talking about? If you have a positive relative energy before the encounter (which you must if you start not in orbit), you must dissipate energy in order to get captured into orbit (which requires a negative relative energy). The masses of the bodies involved do not change that simple physics.
Er, no. A lot of people have worked out how black holes work, Hawking only worked out parts of them. There are many people who have contributed more to the field than he has(Schwartzchild, Kerr, Thorne, etc.). Mostly, he's recognized because he wrote a popular (in both senses) book on science. This isn't to say he isn't very smart, because he is, but let's not get carried away by the back-cover-of-his-books hype.
Also, none of this seems terribly relevant to his opinion that alien life exists. Experts in General Relativity and Quantum Mechanics don't seem like they'd have a particularly special insight on astrobiology, somehow.
I don't think that classifying brilliance by how much they confuse you is really a good way to go about things. In that regards, my more senile professors were friggin' geniuses beyond compare and Einstein was at best mediocre, after all. In fact, I'd argue the opposite: if they can't explain their research in simple enough terms for a fairly average person to understand, that should indicate that perhaps they aren't as brilliant as all that.
Exactly. Hawking is a damn smart guy, but he's not an Einstein or Fermi. Wheeler was in that class. He also left a huge mark on physics with his students from over the years, including Kip Thorne (whom I've frequently heard called the greatest black hole theorist alive, Hawking not withstanding), Hugh Everett (many-worlds interpretation) and Richard Feynman (who needs no parenthetical... d'oh!).
I also got into an argument about Sagan but I had an even harder time defending Sagan than Hawking. Really? I mean, Hawking has done some good work and all, but Sagan is *huge* in the field of planetary science, and not just for his popularization efforts. (Also note that he was popularizing when it was an huge uphill battle against his fellow scientists and not much of a road to glory.) His body of work on planetary atmospheres is sizable and he's another guy whose students have gone on to dominate the field.
Do firefighters compete with one another to get new fire-trucks or hoses? No, the public pays for their equipment. Uh, what's your point? It's OK to dope as long as you're not in competition with other humans? So what if a scientist could show that no one was presently working on the same problem as she was? Is taking enhancing drugs OK then?
In science, the best results win the money. It's a competition, and any competition must have standards to make it fair. Otherwise, why should anyone but the most intelligent, most ruthless, and most uncaring about themselves and others go into science in the first place? Love of science? Thrill of discovery? Hopes of benefiting our fellow humans? Honestly, most scientists I know (including, I think, myself) aren't really ruthless or uncaring. We're here because we enjoy the field, not to get rich or to win fame. (Most of us.)
Even if what you claimed were true, it doesn't invalidate my point one bit. Even to the extent that science involves competition, this isn't a sport. We're not doing this to amuse you, so rules intended to make things sporting don't apply.
I know quite a few scientists who peruse Science and/or Nature regularly. While you probably have a valid underlying point about selection bias, it's not at all clear that your assertion about the readership of Nature is remotely true. Do you have any data to back the claim up?
This is rather different (even accepting that these drugs aren't being taken for legitimate problems) from athletes taking steroids, I think. Athletes are playing games for entertainment purposes. Allowing them to dope up ruins the game to most spectators and the cost-to-benefits ratio is highly questionable. (If the steroids had no side effects, it's not clear to me how that might shift, though.)
A better comparison than athletics might be to a job where strength is still required, like fire-fighting. If you had a fairly safe (I won't pretend that any drug will have no side-effects) steroid that fire-fighters could take to make them stronger and more effective at their jobs, would you permit it? I think it's a fairly similar situation.
And for the record, unless you count about a gallon of various teas per day and Excederin to shoo away the migraines, this scientist is clean of performance-enhancing drugs. On the other hand, I'm kind of slow compared to many colleagues. Hmm...
The effects were certainly worse and it's no surprise that this is first case such as this most of us have seen, but there are many crimes where just being accused by the police will certainly cause significant disruptions to your life, both work and personal. Murder? Rape? Robbery? And what if this had been something related to "national security"? How much you want to be he would have been bundled off somewhere before he had a chance to even protest?
Yeah, people get hysterical about child pornography, but that's not really the central problem with this case. It's a contributing factor, though.
Sure, the implications are worse, but the underlying problem here isn't restricted to kiddie-porn cases and it's well-worth keeping that in mind because it points to a more fundamental problem than with child pornography investigations.
It's certainly part of the problem, yes. Another component is how easy Congress has made it for companies (*any* company, basically) to sell your information to anyone who will pay for it and how difficult it is for you to stop them.
I think other posters have missed the point a bit by focusing on the fact that this case was about child pornography. Yes, that's a particularly egregiously aggressively policed crime, but it's hardly the only time cops will use credit cards to track who they think committed a crime. (Nominal) ownership of the credit card used should *never* be considered sufficient evidence to charge someone with *any* crime. It's probable cause to investigate, sure, but not to charge. It's only about one step more reasonable than charging someone because their real name matched the screen name used.
Any time. I'll have to try to remember to check my notes from Astrobio when I get home from the office today. I may have recorded the mechanism in more detail. On the other hand, probably not: I take lousy notes.
Actually, there's a fair amount of biological truth to that. Females of many species (women, in particular) have evolved to look for a mate who can provide for offspring while the males have evolved to make sure that they display their strengths in this area. A lot of the behaviors in humans that are associated with this aren't even conscious acts, but they're not hard to find.
(And, yes, I know that there is variation between people and other factors can outweigh the above, or even all of what you'd think evolution would have taught us to do. These are overall trends, not blueprints for individual relationships. Also note that I'm not assigning any particular value to these behaviors.)
A quote, no. But I believe that Steve Mojzsis has published work on this, if that helps. He explained it to us in graduate astrobiology, but a) I'm an astrophysicist and b) it was almost a decade ago, so I won't swear to be able to quote stuff back to you.
The gist of it, as I recall, is that heavier isotopes react more sluggishly than lighter ones.
Actually, I believe that the oldest evidence for life is in the isotope ratios in rocks. It's indirect, but it also relies less on chance than fossilization. (Basically, biological processes tend to use more of one isotope than another, leaving the atmosphere enriched relative to the background. So this is a tracer for the presence of biological activity.)
Honestly, even without believing that they're playing political games, I think that this is just about their best option. The Mars program is facing serious cost over-runs and NASA is reining them in. They can do that by going after the older, well-past-their-lifetimes missions, by slashing missions that are recently arrived or about to arrive (such as Phoenix), or by slashing future missions (like Mars Science Lab). The middle option is the worst of the three. The Mars research community sounds very unhappy about the third option (and, to be fair, it will probably return more new science than the rovers will in the future). So...
(Now, granted, from what I understand the cost over-runs are due to MSL, so you can make a very real case that *it* alone should take the blow, but that seems unlikely. At least NASA is keeping this isolated to the Mars program and not slashing entirely different programs for the excesses there.)
Slashdot Mirror
Gah, I missed the fact that < gets consumed by Slashdot's formatting. Everywhere that there's an "E0" in the last post, assume that it's "E<0", please. :-)
Yeah, I would have thought starting it as a 3-body system would work better.
Tides wouldn't work very well I shouldn't think. There's just not enough dissipation at the required rate I'm pretty sure.
There's only one energy here. You are, I think, confusing energy with momentum. These are very different quantities.
Look, here's the energy of two gravitationally interacting bodies:
E = 1/2 (m1 v1^2 + m2 v2^2) - G m1 m1/r
For gravitationally bound bodies (i.e., in orbit), E0. (E=0 basically never happens for statistical reasons.)
Now, gravitation is a conservative force (never mind how you prove that for now), so E does not change during an interaction. v1 and v2 might increases as r decreases, by E does not change.
So if you start unbound (E>0), you cannot get E0 unless you dissipate energy. The gravity of the two bodies cannot change their mutual binding energy, so you need some other process.
Arg, no. No, no, and no.
Momentum is not energy. They are separate quantities and are conserved separately. The mass of the star is, as I stated earlier, irrelevant. When you have two bodies, the bind energy DOES NOT CHANGE during an interaction without some other dissipation. Gravity is a conservative force.
Look, I appreciate that you're throwing ideas out there, but this is pretty basic physics that we have a good handle on. If you don't believe me (which is fine!), look some of this stuff up for yourself.
Also, for the record, the star is less massive than the pulsar: the diagram of the orbits that I saw made it pretty clear that the star has the larger orbit.
You miss the point. They cannot be in orbit if they started out not in orbit UNLESS there is energy lost during the capturing. This is basic physics stemming for binding energies.
With planets, you can dissipate energy this with atmospheric drag, firing rockets (if you're a spacecraft), or three-body capture*. Only the last of these works with stars, and that's a dubious proposition since the millisecond pulsar would probably have been pretty close to its partner before the capture making it hard to strip during the encounter.
* In the interest of honesty, tides and gravity waves might do it, too, but in practice, their timescale for action is much too long to assist a capture.
What the heck are you talking about? If you have a positive relative energy before the encounter (which you must if you start not in orbit), you must dissipate energy in order to get captured into orbit (which requires a negative relative energy). The masses of the bodies involved do not change that simple physics.
How do you capture a pulsar? You have to shed energy somehow. I suppose binary capture is possible, but that seems like the only real option here.
Er, no. A lot of people have worked out how black holes work, Hawking only worked out parts of them. There are many people who have contributed more to the field than he has(Schwartzchild, Kerr, Thorne, etc.). Mostly, he's recognized because he wrote a popular (in both senses) book on science. This isn't to say he isn't very smart, because he is, but let's not get carried away by the back-cover-of-his-books hype.
Also, none of this seems terribly relevant to his opinion that alien life exists. Experts in General Relativity and Quantum Mechanics don't seem like they'd have a particularly special insight on astrobiology, somehow.
I've addressed the misunderstanding below, but...
I don't think that classifying brilliance by how much they confuse you is really a good way to go about things. In that regards, my more senile professors were friggin' geniuses beyond compare and Einstein was at best mediocre, after all. In fact, I'd argue the opposite: if they can't explain their research in simple enough terms for a fairly average person to understand, that should indicate that perhaps they aren't as brilliant as all that.
Heh, I was wondering. Kip Thorne is as white as Hawking, so the jump to race had me sort of confused.
You got it. Phil Plait (aka, The Bad Astronomer) ranted about this today.
Even if what you claimed were true, it doesn't invalidate my point one bit. Even to the extent that science involves competition, this isn't a sport. We're not doing this to amuse you, so rules intended to make things sporting don't apply.
I know quite a few scientists who peruse Science and/or Nature regularly. While you probably have a valid underlying point about selection bias, it's not at all clear that your assertion about the readership of Nature is remotely true. Do you have any data to back the claim up?
This is rather different (even accepting that these drugs aren't being taken for legitimate problems) from athletes taking steroids, I think. Athletes are playing games for entertainment purposes. Allowing them to dope up ruins the game to most spectators and the cost-to-benefits ratio is highly questionable. (If the steroids had no side effects, it's not clear to me how that might shift, though.)
A better comparison than athletics might be to a job where strength is still required, like fire-fighting. If you had a fairly safe (I won't pretend that any drug will have no side-effects) steroid that fire-fighters could take to make them stronger and more effective at their jobs, would you permit it? I think it's a fairly similar situation.
And for the record, unless you count about a gallon of various teas per day and Excederin to shoo away the migraines, this scientist is clean of performance-enhancing drugs. On the other hand, I'm kind of slow compared to many colleagues. Hmm...
The effects were certainly worse and it's no surprise that this is first case such as this most of us have seen, but there are many crimes where just being accused by the police will certainly cause significant disruptions to your life, both work and personal. Murder? Rape? Robbery? And what if this had been something related to "national security"? How much you want to be he would have been bundled off somewhere before he had a chance to even protest?
Yeah, people get hysterical about child pornography, but that's not really the central problem with this case. It's a contributing factor, though.
Sure, the implications are worse, but the underlying problem here isn't restricted to kiddie-porn cases and it's well-worth keeping that in mind because it points to a more fundamental problem than with child pornography investigations.
It's certainly part of the problem, yes. Another component is how easy Congress has made it for companies (*any* company, basically) to sell your information to anyone who will pay for it and how difficult it is for you to stop them.
I think other posters have missed the point a bit by focusing on the fact that this case was about child pornography. Yes, that's a particularly egregiously aggressively policed crime, but it's hardly the only time cops will use credit cards to track who they think committed a crime. (Nominal) ownership of the credit card used should *never* be considered sufficient evidence to charge someone with *any* crime. It's probable cause to investigate, sure, but not to charge. It's only about one step more reasonable than charging someone because their real name matched the screen name used.
Any time. I'll have to try to remember to check my notes from Astrobio when I get home from the office today. I may have recorded the mechanism in more detail. On the other hand, probably not: I take lousy notes.
Actually, there's a fair amount of biological truth to that. Females of many species (women, in particular) have evolved to look for a mate who can provide for offspring while the males have evolved to make sure that they display their strengths in this area. A lot of the behaviors in humans that are associated with this aren't even conscious acts, but they're not hard to find.
(And, yes, I know that there is variation between people and other factors can outweigh the above, or even all of what you'd think evolution would have taught us to do. These are overall trends, not blueprints for individual relationships. Also note that I'm not assigning any particular value to these behaviors.)
A quote, no. But I believe that Steve Mojzsis has published work on this, if that helps. He explained it to us in graduate astrobiology, but a) I'm an astrophysicist and b) it was almost a decade ago, so I won't swear to be able to quote stuff back to you.
The gist of it, as I recall, is that heavier isotopes react more sluggishly than lighter ones.
Actually, I believe that the oldest evidence for life is in the isotope ratios in rocks. It's indirect, but it also relies less on chance than fossilization. (Basically, biological processes tend to use more of one isotope than another, leaving the atmosphere enriched relative to the background. So this is a tracer for the presence of biological activity.)
... the number of mid-air fatal beatings of fellow passengers with in-flight meals is about to rise 5000%.
Honestly, even without believing that they're playing political games, I think that this is just about their best option. The Mars program is facing serious cost over-runs and NASA is reining them in. They can do that by going after the older, well-past-their-lifetimes missions, by slashing missions that are recently arrived or about to arrive (such as Phoenix), or by slashing future missions (like Mars Science Lab). The middle option is the worst of the three. The Mars research community sounds very unhappy about the third option (and, to be fair, it will probably return more new science than the rovers will in the future). So...
(Now, granted, from what I understand the cost over-runs are due to MSL, so you can make a very real case that *it* alone should take the blow, but that seems unlikely. At least NASA is keeping this isolated to the Mars program and not slashing entirely different programs for the excesses there.)