You've obviously never heard of spontaneous pair production, have you. Heisenberg's UP allows for th creation of particle-antiparticle pair so long as their lifespan dt (the time between creation and annihilation) obeys dE*dt >~ h. This says that the heavier the particles (with larger rest mass energy) and their antiparticle partners, the shorter period of time they can exist.
Such pair production is present in Hawkings theory regarding black hole radiation. The idea there is that these particle-antiparticle pairs are formed near the event horizon of a black hole. Before the pair can annihilate, one of the particles crosses the event horizon. The other member of the pair no longer has a partner with which to annihilate, and by conservation of momentum, moves away from the black hole, appearing to eminate from the black hole itself.
Getting back to ZPE of the universe, current theory proposes that the vacuum of space can be thought of as quantum harmonic oscillators, which would allow a non-zero vacuum energy, which in turn allows pair production.
Just remember, quantum theory says that every event, no matter how improbable, still has a non-zero chance of happening.
>I do not see anyone here ranting about the US Postal Service or other government institutions that have monopoly power.
"Er, that's because they are owned by the people. If they start acting like an abusive monopoly, the public can easily get involved and fix it."
Really? I don't remember getting to vote on increases in postal rates. The only voting I can remember is "Fat Elvis" vs. "Skinny Elvis" and other such stamp image issues, certainly not about the monetary values of these stamps.
To comment on the previous post... this isn't technically correct.
Capital omega (you try typing one) is the ratio of the overall (mass + energy + cosmological) density divided by the critical density (remember, mass IS energy, E=mc^2). In a flat universe, Omega = 1; closed, Omega > 1; open, Omega 1.
Open means the universe will expand forever, with no limit on the physical size. Flat means the expansion will slow to zero in an infinite amount of time, producing a finite physical size to the universe. Closed means self-gravitation of the universe will win out, halting the expansion of the universe, and causing it to re-collapse, presumbly into a "Big Crunch".
The baryonic matter (massive particles such as protons, neutrons, etc.) and photons (light/energy) are all the stuff we see, and is though to have density of about 0.1-0.3 of the critical density.
The cosmological constant (the was invented, then abandoned by Einstein) is a mathematical embodiment that the "vacuum" of space is not actually empty, but full of energy fluctuations that create particle/anti-particle pairs, which annihilate each other in an incredibly short amount of time. This "zero-point" energy would add to the total mass/energy of the universe, and increase the density.
q_0 is the deceleration parameter, equal to 1/2 for a flat universe. If q_0 > 1/2, the deceleration rate is greater, and the universe is closed. If q_0 The current theory is the the density of baryonic matter and light/energy (Omega_b) and the contribution of the cosmological constant (Omega_Lambda) add up to exactly equal the critical density, Omega_total = 1.
Eric (who just finished a stint as teaching assistant for a class in astrophysics and cosmology).
All motion is relative, so sayeth Albert Einstein. As such, what we measure is the rate at which objects are moving away from us, as observed by us.
If a galaxy is seen to be moving away from us at 1000 km/s, an observer halfway between that galaxy and ours would see both of them receding at ~500 km/s (approximately, the effects of special relativity are quite small at such paltry speeds).
To use your analogy, suppose you were sitting at the exact point someone hit the water with the stone. Both ants would be moving away from you at the speed of the wave (assuming they are on miniature surfboards). Each ant, in his own "stationary" reference frame, would see you moving away at the speed of the wave, and would see the other ant moving away at twice the wave speed.
This is, of course, a classical example. If the speeds are relativistic, the expression is no longer v_r = v_1 + v_2, rather v_r = (v_1 + v_2) / (1 + v_1*v_2/c^2), limiting the relative velocity to the speed of light, c.
"A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed."
Lessee, a well regulated militia, being necessary to the security of a free state... isn't that the job of the armed forces?
And, tell me where the following "translation" fails...
Because a well-regulated militia is necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed.
Lessee, you claim that your interpretation is backed up by statements by the Founders. Thanks for backing up one of my points... This amendment was drafted over 200 years ago. Times have changed. 200 years ago, you didn't have a person walking down the street, or into a public building and start firing randomly. There wasn't a need for strict gun control. People knew how to control themselves. Ideally, we *should* be able to act in the same way. Unfortunately, we aren't. Thus, something needs to be done.
Finally, where in my comments did I make ANY statements about those who own and use firearms *responsibly*? I never stated that guns should be outlawed. Personally, I know an entire branch of my family that would starve if they were no longer allowed to own their.3006 rifles. They hunt deer for sustinence.
But, what is the purpose of a semi-automatic or automatic weapon? To kill people. Don't tell me you need 30+ rounds a second to take down Bambi... there won't be much left to eat at that point.
Since you obviously were putting words into my mouth about gun laws, let me express my views for you, just to clear up any misconceptions...
It should be illegal for a citizen to own an automatic or semi-automatic weapon. Keep them in the armed services, where people are properly trained in their use, and *when* to use them. Srticter control of handguns is needed. At this point, it would be useless to ban them. There are too many of them, and it is too easy to obtain one. However, more thorough background checks, and mandatory supervised instruction should be required. Same for rifles and shotguns. Point of sale of these firearms should be more tightly controlled. As it is now, a 16 year old can walk into the local Wal-Mart and buy a rifle and ammo all without so much as an age check. There is a reason we have age limits on so-called adult activities (driving, drinking, etc.): Most 16 year olds aren't emotionally and socially mature enough to partake of them responsibly.
I hope I cleared up your misconceptions of my position.
PS I think my point about repealing amendments was quite clear. Thanks for backing that up, too.
I fail to see how allowing every person in our society to wield guns like some idiot falls under the clause "A well regulated militia"
The second amendment was drafted and ratified over 200 years ago, coming off the heels of the war to gain independence from England. At that time, there was little in the way of formal armed forces, thus the need to the average man to keep and bear arms to protect "...the security of a free state..."
The "right of the people to keep and bear arms" was justified by the need for a "well regulated militia". In this day and age, with the technology available to us and the size of our "well regulated" armed forces, the 2nd amendment is hopelessly out of date.
Oh, and if you want to argue about the inviolability of the amendments to the constitution, might I remind you of the amendment which outlawed liquor... repealed in about 15 years.
And yes, a gun CAN change someone's behavior. Suppose you were the 98 lb weakling who was always picked on, but too small to defend yourself. Now, add a gun to the mix. You aren't such a "weakling" now, in that you can hurt/maim/kill your tormentors, just as the kids in Colorado apparently did.
Minds are like parachutes... they work best when open.
WTF were two high school kids doing with an entire friggin' arsenal? I mean, semi-automatic weapons, sawed-off shotguns, and enough explosives to blast open most bank safes!
Who gives a fat rat's ass HOW they were killed!!! Jesus F'in' Christ!!! It almost sounds as if you approve of the use of bombs, because it supports the inane statement that "guns don't kill people, people kill people", and since some of them were killed by bombs, well, that's OK.
You know, you should read Miller's "A Canticle for Leibowitz". Gives you an idea of exactly what we might be preserving after 2000 years... As I recall, one of the holy relics was an incomplete shopping list.
Newton's third law... For every force, there is an equal and opposite reaction force.
When two gravitationally bound objects orbit each other, they are both orbiting the common center of mass. As measured from the center of mass, M_1*r_1 = M_2*r_2 where the r's are the radius of the orbit. If the orbits are elliptical, it doesn't matter. The center of mass of a two-body system doesn't change position with respect to the two bodies, the product remains constant. As one body moves farther from the center of mass, so does the other one, to preserve the equality.
Stellar masses, although difficult to measure, can be found indirectly from spectral observation. The wobble in the stars position indicates the distance of the star from the center of mass, while the distance to the planet is directly measured. Thus, you get the planetary mass.
It IS true that we cannot see other planets, it isn't due to the amount of light that their star is emitting. IIRC, the gas disks around beta Pictoris and Vega were both imaged using a "stellar block" (I don't know what the actual name is, but, if you've seen "Who Shot Mr. Burns?", you get the idea). They have ways to block the light from the star, and see the dim objects in their immediate neighborhood. As someone else mentioned, you are diffraction limited to angular sizes much greater than the planets span at such distances.
Did you read the article? Where in there did anyone say they we have evidence of extraterrestrial life? Nowhere. All we (yes, I AM an astrophysicists...theoretical though) are saying is that our Sun is not alone in having a system of planets. System of planets != life on other planets. Not yet anyway.
Nuclei are composed of protons and (except in normal hydrogen) neutrons. That makes them positively charged. Positive charges repel each other. As the original poster said, you have to give the nuclei extremely large amounts of energy to get the nuclei close enough for the strong nuclear force to dominate.
A quick estimate... nuclei are of the order 10^-15 m in size. The potential barrier between two protons at this separation is about 230 J. This energy is comparable to that of a a 16lb (7.3 kg) bowling ball moving at 26.3 ft/s (8 m/s). That's a lot of damn energy for two sub-atomic particles to have. The temperature required for this to take place is on the order of millions of Kelvin. I hardly call that COLD fusion.
I don't care how much damn funding you give them, you can't push two protons together at room temperature (300K or so).
And your analogy about the Earth being the center of the Universe isn't even relevant. That came from the idea that God made man in His image, and thus, we must be the favored of all His creations. Then, there were incomplete observations to "support" this theory.
Cold fusion is doomed by the fundamental laws of physics, which we have a much better grasp of that we did hundreds of years ago.
Neither Anonymous, nor a Coward... just a spam hater.
That's 1.3 kW *per square meter*, or in other words, that is the flux. Given 100% efficiency, a 1 m^2 solar panel would be able to power 13 100W light bulbs. Of course, we can talk about major appliances... ISTR my microwave oven requires about 6-700 W, that's a.5 m^2 panel.
Of course, there is the problem with overcast days... what do you do when you have a cold front stalled in your area, and are without any direct sunlight for a week? Your reserves are sorely taxed, if not completely depleted.
There are efficiency, storage, and distribution issues to consider, also. What about "power plants"? Would they install solar panels on your roof, then charge you for the energy they store? Or would it be a privately owned panel? In that case, what are you to do when yours goes offline? Expect some good natured neighbor to let you tap into his reserves?
I just don't see how solar power is feasible as a major source of energy.
1) Absolute zero is defined as all motion (including atomic vibrations) have stopped. Somehow, I doubt this allow for a gas at that point.
2) (PV = 0) != (V = 0). P is the internal pressure of the gas. When all atomic motion has ceased, the material can no longer exert any force on the container, hence, no pressure
Yeah right. There's surf in the fall...when the hurricane season peaks. That's about it. If you are into "sight-seeing" (*wink wink*) you'll be in luck, though.
What about those of us who live in Raleigh, and grew up in Wilmington/Wrightsville Beach? Will they take us up in a plane, circle the area for 1/2 hour, then land?
Slashdot Mirror
You've obviously never heard of spontaneous pair production, have you. Heisenberg's UP allows for th creation of particle-antiparticle pair so long as their lifespan dt (the time between creation and annihilation) obeys dE*dt >~ h. This says that the heavier the particles (with larger rest mass energy) and their antiparticle partners, the shorter period of time they can exist.
Such pair production is present in Hawkings theory regarding black hole radiation. The idea there is that these particle-antiparticle pairs are formed near the event horizon of a black hole. Before the pair can annihilate, one of the particles crosses the event horizon. The other member of the pair no longer has a partner with which to annihilate, and by conservation of momentum, moves away from the black hole, appearing to eminate from the black hole itself.
Getting back to ZPE of the universe, current theory proposes that the vacuum of space can be thought of as quantum harmonic oscillators, which would allow a non-zero vacuum energy, which in turn allows pair production.
Just remember, quantum theory says that every event, no matter how improbable, still has a non-zero chance of happening.
--
>I do not see anyone here ranting about the US Postal Service or other government institutions that have monopoly power.
"Er, that's because they are owned by the people. If they start acting like an abusive monopoly, the public can easily get involved and fix it."
Really? I don't remember getting to vote on increases in postal rates. The only voting I can remember is "Fat Elvis" vs. "Skinny Elvis" and other such stamp image issues, certainly not about the monetary values of these stamps.
Chrs
Eric
That link was about many products competing for the title "World's Smallest Web-Server"
Besides, I didn't see UMass on that list.
So I guess any references to my old Ford Escort are right out!
Eric
Hmmm... why doesn't a plaid old text post allow the less than symbol???
The last part of the first paragraph should read open, Omega 1.
(When will I learn to use the preview button?)
To comment on the previous post... this isn't technically correct.
Capital omega (you try typing one) is the ratio of the overall (mass + energy + cosmological) density divided by the critical density (remember, mass IS energy, E=mc^2). In a flat universe, Omega = 1; closed, Omega > 1; open, Omega 1.
Open means the universe will expand forever, with no limit on the physical size. Flat means the expansion will slow to zero in an infinite amount of time, producing a finite physical size to the universe. Closed means self-gravitation of the universe will win out, halting the expansion of the universe, and causing it to re-collapse, presumbly into a "Big Crunch".
The baryonic matter (massive particles such as protons, neutrons, etc.) and photons (light/energy) are all the stuff we see, and is though to have density of about 0.1-0.3 of the critical density.
The cosmological constant (the was invented, then abandoned by Einstein) is a mathematical embodiment that the "vacuum" of space is not actually empty, but full of energy fluctuations that create particle/anti-particle pairs, which annihilate each other in an incredibly short amount of time. This "zero-point" energy would add to the total mass/energy of the universe, and increase the density.
q_0 is the deceleration parameter, equal to 1/2 for a flat universe. If q_0 > 1/2, the deceleration rate is greater, and the universe is closed. If q_0
The current theory is the the density of baryonic matter and light/energy (Omega_b) and the contribution of the cosmological constant (Omega_Lambda) add up to exactly equal the critical density, Omega_total = 1.
Eric (who just finished a stint as teaching assistant for a class in astrophysics and cosmology).
All motion is relative, so sayeth Albert Einstein. As such, what we measure is the rate at which objects are moving away from us, as observed by us.
If a galaxy is seen to be moving away from us at 1000 km/s, an observer halfway between that galaxy and ours would see both of them receding at ~500 km/s (approximately, the effects of special relativity are quite small at such paltry speeds).
To use your analogy, suppose you were sitting at the exact point someone hit the water with the stone. Both ants would be moving away from you at the speed of the wave (assuming they are on miniature surfboards). Each ant, in his own "stationary" reference frame, would see you moving
away at the speed of the wave, and would see the other ant moving away at twice the wave speed.
This is, of course, a classical example. If the speeds are relativistic, the expression is no longer v_r = v_1 + v_2, rather v_r = (v_1 + v_2) / (1 + v_1*v_2/c^2), limiting the relative velocity to the speed of light, c.
Eric
Actually, it's "Never go in against a Sicilian when death is on the line."
Eric
"A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed."
.3006 rifles. They hunt deer for sustinence.
Lessee, a well regulated militia, being necessary to the security of a free state... isn't that the job of the armed forces?
And, tell me where the following "translation" fails...
Because a well-regulated militia is necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed.
Lessee, you claim that your interpretation is backed up by statements by the Founders. Thanks for backing up one of my points... This amendment was drafted over 200 years ago. Times have changed. 200 years ago, you didn't have a person walking down the street, or into a public building and start firing randomly. There wasn't a need for strict gun control. People knew how to control themselves. Ideally, we *should* be able to act in the same way. Unfortunately, we aren't. Thus, something needs to be done.
Finally, where in my comments did I make ANY statements about those who own and use firearms *responsibly*? I never stated that guns should be outlawed. Personally, I know an entire branch of my family that would starve if they were no longer allowed to own their
But, what is the purpose of a semi-automatic or automatic weapon? To kill people. Don't tell me you need 30+ rounds a second to take down Bambi... there won't be much left to eat at that point.
Since you obviously were putting words into my mouth about gun laws, let me express my views for you, just to clear up any misconceptions...
It should be illegal for a citizen to own an automatic or semi-automatic weapon. Keep them in the armed services, where people are properly trained in their use, and *when* to use them. Srticter control of handguns is needed. At this point, it would be useless to ban them. There are too many of them, and it is too easy to obtain one. However, more thorough background checks, and mandatory supervised instruction should be required. Same for rifles and shotguns. Point of sale of these firearms should be more tightly controlled. As it is now, a 16 year old can walk into the local Wal-Mart and buy a rifle and ammo all without so much as an age check. There is a reason we have age limits on so-called adult activities (driving, drinking, etc.): Most 16 year olds aren't emotionally and socially mature enough to partake of them responsibly.
I hope I cleared up your misconceptions of my position.
PS I think my point about repealing amendments was quite clear. Thanks for backing that up, too.
A well regulated militia...
I fail to see how allowing every person in our society to wield guns like some idiot falls under the clause "A well regulated militia"
The second amendment was drafted and ratified over 200 years ago, coming off the heels of the war to gain independence from England. At that time, there was little in the way of formal armed forces, thus the need to the average man to keep and bear arms to protect "...the security of a free state..."
The "right of the people to keep and bear arms" was justified by the need for a "well regulated militia". In this day and age, with the technology available to us and the size of our "well regulated" armed forces, the 2nd amendment is hopelessly out of date.
Oh, and if you want to argue about the inviolability of the amendments to the constitution, might I remind you of the amendment which outlawed liquor... repealed in about 15 years.
And yes, a gun CAN change someone's behavior. Suppose you were the 98 lb weakling who was always picked on, but too small to defend yourself. Now, add a gun to the mix. You aren't such a "weakling" now, in that you can hurt/maim/kill your tormentors, just as the kids in Colorado apparently did.
Minds are like parachutes... they work best when open.
Jackasses *with* guns kill people.
WTF were two high school kids doing with an entire friggin' arsenal? I mean, semi-automatic weapons, sawed-off shotguns, and enough explosives to blast open most bank safes!
The bus just went by, and you missed it...badly!
Who gives a fat rat's ass HOW they were killed!!! Jesus F'in' Christ!!! It almost sounds as if you approve of the use of bombs, because it supports the inane statement that "guns don't kill people, people kill people", and since some of them were killed by bombs, well, that's OK.
Get a grip!
You know, you should read Miller's "A Canticle for Leibowitz". Gives you an idea of exactly what we might be preserving after 2000 years... As I recall, one of the holy relics was an incomplete shopping list.
Plug and chug on this, then...
Newton's third law... For every force, there is an equal and opposite reaction force.
When two gravitationally bound objects orbit each other, they are both orbiting the common center of mass. As measured from the center of mass, M_1*r_1 = M_2*r_2 where the r's are the radius of the orbit. If the orbits are elliptical, it doesn't matter. The center of mass of a two-body system doesn't change position with respect to the two bodies, the product remains constant. As one body moves farther from the center of mass, so does the other one, to preserve the equality.
Stellar masses, although difficult to measure, can be found indirectly from spectral observation. The wobble in the stars position indicates the distance of the star from the center of mass, while the distance to the planet is directly measured. Thus, you get the planetary mass.
It IS true that we cannot see other planets, it isn't due to the amount of light that their star is emitting. IIRC, the gas disks around beta Pictoris and Vega were both imaged using a "stellar block" (I don't know what the actual name is, but, if you've seen "Who Shot Mr. Burns?", you get the idea). They have ways to block the light from the star, and see the dim objects in their immediate neighborhood. As someone else mentioned, you are diffraction limited to angular sizes much greater than the planets span at such distances.
Better example, less touchy subject.
It is standard practice to use Galaxy when referring to our own Milky Way, and galaxy when talking about galaxies in general.
Did you read the article? Where in there did anyone say they we have evidence of extraterrestrial life? Nowhere. All we (yes, I AM an astrophysicists...theoretical though) are saying is that our Sun is not alone in having a system of planets. System of planets != life on other planets. Not yet anyway.
Brief lesson in physics:
... nuclei are of the order 10^-15 m in size. The potential barrier between two protons at this separation is about 230 J. This energy is comparable to that of a a 16lb (7.3 kg) bowling ball moving at 26.3 ft/s (8 m/s). That's a lot of damn energy for two sub-atomic particles to have. The temperature required for this to take place is on the order of millions of Kelvin. I hardly call that COLD fusion.
Nuclei are composed of protons and (except in normal hydrogen) neutrons. That makes them positively charged. Positive charges repel each other. As the original poster said, you have to give the nuclei extremely large amounts of energy to get the nuclei close enough for the strong nuclear force to dominate.
A quick estimate
I don't care how much damn funding you give them, you can't push two protons together at room temperature (300K or so).
And your analogy about the Earth being the center of the Universe isn't even relevant. That came from the idea that God made man in His image, and thus, we must be the favored of all His creations. Then, there were incomplete observations to "support" this theory.
Cold fusion is doomed by the fundamental laws of physics, which we have a much better grasp of that we did hundreds of years ago.
Neither Anonymous, nor a Coward... just a spam hater.
That's 1.3 kW *per square meter*, or in other words, that is the flux. Given 100% efficiency, a 1 m^2 solar panel would be able to power 13 100W light bulbs. Of course, we can talk about major appliances... ISTR my microwave oven requires about 6-700 W, that's a .5 m^2 panel.
Of course, there is the problem with overcast days... what do you do when you have a cold front stalled in your area, and are without any direct sunlight for a week? Your reserves are sorely taxed, if not completely depleted.
There are efficiency, storage, and distribution issues to consider, also. What about "power plants"? Would they install solar panels on your roof, then charge you for the energy they store? Or would it be a privately owned panel? In that case, what are you to do when yours goes offline? Expect some good natured neighbor to let you tap into his reserves?
I just don't see how solar power is feasible as a major source of energy.
Learn some physics first...
1) Absolute zero is defined as all motion (including atomic vibrations) have stopped. Somehow, I doubt this allow for a gas at that point.
2) (PV = 0) != (V = 0). P is the internal pressure of the gas. When all atomic motion has ceased, the material can no longer exert any force on the container, hence, no pressure
Yeah right. There's surf in the fall...when the hurricane season peaks. That's about it. If you are into "sight-seeing" (*wink wink*) you'll be in luck, though.
Signed,
A longtime Wilmington resident
What about those of us who live in Raleigh, and grew up in Wilmington/Wrightsville Beach? Will they take us up in a plane, circle the area for 1/2 hour, then land?
This is posted at msnbc.com. Any questions?
follow up... well, the archive is anyway.