and a constant velocity of 150 mph (it wouldn't be),
Why so slow? HSR is generally being designed today for 200-250 mph. And on this route, on all new track and with stops fairly far apart I see no reason why that shouldn't be sustained virtually all the time. That gives you 20-25 hours to Paris to Beijing and 25-30 hours on to Shanghai, city centre to city centre.
If the software and control system of a modern passenger car does not allow for a complete verification of 2 pedal and 1 steering sensors, 4 brake and 1 steering actuator and 2 brake lights, then this software is unfit for its intended purpose. If the system does not allow specific subset of commands to be scientifically, mathematically verified to work as intended even in cases where non-verified parts of the software return any combination of valid and invalid values, then the subsetting structure of that system must be regarded as a complete failure.
You've forgotten about the numerous sensors INSIDE the engine, transmission, etc. I don't know what type of engine these cars had, but if its achieving anything like the levels of power, economy and reliability expected in modern cars it will have several hundred sensors inside the engine, and actuators firing many times per engine revolution to control fuel injection, ignition, valve timing, etc. as well as monitoring temperatures, oil pressure, air flow, exhaust composition, brake pad wear, wheel rotation, etc. Making an intenal combustion engine work at peak efficiency is NOT simple.
Ok, then. More rain and snow prove global warming. And drought proves global warming. So..... given that any changes in the weather prove global warming, what would disprove global warming?
Heads I win, tails you lose, right?
Sorry, I'm afraid it just IS complicated. Global warming will (we believe) lead to more precipitation in some places at some times of year, and less precipitation in other place at other times of year, on average over many decades. It may also change the "variance" leading to weather with more very wet and very dry years. "Proving" or "disproving" theories about the climate will typically involve a subtle statistical analysis of data over the whole planet and probably over several decades.
There is no real interest in measuring absolute time here. What these clocks really are is ultra-stable oscillators and by (carefully) counting their oscillations, they can be used to measure intervals.
I take your point about the quarks. The point about mass though is that there is a privileged frame in this context, namely the rest frame of the eventual black hole. If you are in some other frame you will see a HIGHER mass, since you will see a moving black hole at the end of the day. Another way of seeing it is that the energy put into accelerating the protons ends up in the rest mass of the black hole.
If we were to collide two protons with enough energy to produce a black hole, you would end up with (very temporarily) a black hole that has the mass (and thus gravitational pull) of two protons, with an electric charge of +2.
Not true, or at least not the way you mean. Each of the protons going into the collision carries its rest mass, but also the extra mass due to the fact it's moving at almost light-speed. In the case of the LHC this is about 10000 times greater, so you end up with a black hole with the mass of roughly 20002 protons (and, indeed charge +2).
Really nice for laptop users. Dump laptop on desk, plug in two cables (power and displayport) and have your whole desktop setup connected. Be nice if displayport could also supply 100W or so of DC power.
Assuming their technology is advanced, but not magic -- ie they are working within the physical laws as we understand them, then they still have to obey conservation of energy and dump waste heat somehow. The colder the temperatures they, or their machines, work at, the larger they can make the sphere and the longer the wavelength of the dumped heat but it still comes out somewhere. If they were so numerous as to be very much of the dark matter, they'd show up as a pattern in the cosmic microwave background, (since we know where the dark matter is) and they don't.
if someone managed to build a Dyson sphere around their star to harvest all of it's solar output, we wouldn't see that star. Just like you can't see a match when it's in a box. Possibly the only way to detect it would be via its gravity.
Not so. The Dyson sphere would reradiate all the star's output as waste heat at whatever temperature the inhabitants liked to live. It would look like a large infrared giant, instead of a small yellow star.
The units are appropriate. What this says is that to get the shuttle to that speed (assuming perfect efficiency) we need as much energy as all the sunlight that hits Earth in 10^4 seconds (about 3 hours). In other words, a lot, but not a completely silly amount.
If we convert that energy to mass, we see that we need about 10^4 kg, ie about 5 tons of anti-matter and 5 tons of matter, somehow combined and used as propellant with perfect efficiency.
I don't get it! Surely their perspective of the time to get there must be longer than it would take light to get there if they are travelling at Sub Light speeds? Our perspective may well see it as even longer, but they can't get there in less time than light if they travel slower than light?
Or maybe I need to pick up a Relativity Made Easy book...
Maybe you do. From their perspective what their engines are doing is accelerating and then "squashing" the universe along the direction of thrust. They see 61 Virginis approaching them at almost light-speed, for most of the flight, but, in the middle, they measure the distance from the sun to 61V as significantly less than 28 ly. No one ever overtakes a light beam or sees anything else do so.
All self-contained propulsion systems (chemical, ion, nuclear pulse, fusion rocket,whatever) basically do the same job: convert part of the rest mass of the rocket into kinetic energy of the rocket (as seen from Earth). Then to stop you have to do the same job again, as seen from the frame of reference comoving with the rocket at top speed.
To get to relativistic velocities, where you experience time dilation,
you have to covert most of the rest mass into energy and efficiently transform all of that into KE.
This rules out fission and even fusion as power sources. You have to use antimatter, and quite a lot of it (as a proportion of your launch mass). Nothing else is power- dense enough.
Non self-contained systems are easier -- laser propelled light-sails; beam propelled magsails; gravity catapults.
I did read that article. It didn't answer the question. The quantum vacuum consists of (at the energy levels we're dealing with) virtual photons. If we're giving net momentum to these virtual photons I think that is the same thing as there being real photons travelling in the appropriate direction. So, you move some charges and magnetic dipoles around, and you photons start moving -- how is this different from emitting something from an antenna?
And all electromagnetic forces are carried by photons so there isn't a difference in strength.
Is dumping momentum into the quantum vacuum different from emitting photons carrying the same momentum? If not, this is just a photon drive, which is a well known concept, has brilliant specific impulse but is incredibly energy-inefficient except at high relatavistic velocities.
OK "Every" was careless, but neither of the studies you mention shows any sign of being peer-reviewed. The first one, which I flicked through briefly offers no detailed information about its data selection or analysis.
I still maintain that the weight of evidence is overwhelmingly in favour of AGW and the need to act on emissions.
The more science is viewed with skepticism the better the science will be in my opinion.
Fair enough, but sometimes you have to make a decision now, based on what you know now. If you allow your "skepticism" to turn into "I'll make decisions based on the theory that is most personally convenient to me, even if the current evidence, while not conclusive, weighs against it" then you are not just being skeptical, you're being foolish.
Every serious scientific review that has looked at the evidence carefully (and at the raw data and at the analysis procedures, etc.) has concluded that the balance of evidence strongly supports AGW and strongly supports action now to curb emissions.
It is possible that in ten years time the balance of evidence will shift (or even tomorrow) but for the decisions we have to make today, that is irrelevant.
Climate Science is a STUDY, much like Social Studies, Political "Science", and most (but not all) fields of Psychology. You cannot experiment on Climate on the timeframes or scales these "scientists" are suggesting. You cannot produce a hypothesis, alter variables, and confirm or deny your ideas.
Slashdot Mirror
and a constant velocity of 150 mph (it wouldn't be),
Why so slow? HSR is generally being designed today for 200-250 mph. And on this route, on all new track and with stops fairly far apart I see no reason why that shouldn't be sustained virtually all the time. That gives you 20-25 hours to Paris to Beijing and 25-30 hours on to Shanghai, city centre to city centre.
If the software and control system of a modern passenger car does not allow for a complete verification of 2 pedal and 1 steering sensors, 4 brake and 1 steering actuator and 2 brake lights, then this software is unfit for its intended purpose. If the system does not allow specific subset of commands to be scientifically, mathematically verified to work as intended even in cases where non-verified parts of the software return any combination of valid and invalid values, then the subsetting structure of that system must be regarded as a complete failure.
You've forgotten about the numerous sensors INSIDE the engine, transmission, etc. I don't know what type of engine these cars had, but if its achieving anything like the levels of power, economy and reliability expected in modern cars it will have several hundred sensors inside the engine, and actuators firing many times per engine revolution to control fuel injection, ignition, valve timing, etc. as well as monitoring temperatures, oil pressure, air flow, exhaust composition, brake pad wear, wheel rotation, etc. Making an intenal combustion engine work at peak efficiency is NOT simple.
Ok, then. More rain and snow prove global warming. And drought proves global warming. So..... given that any changes in the weather prove global warming, what would disprove global warming?
Heads I win, tails you lose, right?
Sorry, I'm afraid it just IS complicated. Global warming will (we believe) lead to more precipitation in some places at some times of year, and less precipitation in other place at other times of year, on average over many decades. It may also change the "variance" leading to weather with more very wet and very dry years. "Proving" or "disproving" theories about the climate will typically involve a subtle statistical analysis of data over the whole planet and probably over several decades.
There is no real interest in measuring absolute time here. What these clocks really are is ultra-stable oscillators and by (carefully) counting their oscillations, they can be used to measure intervals.
I take your point about the quarks. The point about mass though is that there is a privileged frame in this context, namely the rest frame of the eventual black hole. If you are in some other frame you will see a HIGHER mass, since you will see a moving black hole at the end of the day. Another way of seeing it is that the energy put into accelerating the protons ends up in the rest mass of the black hole.
If we were to collide two protons with enough energy to produce a black hole, you would end up with (very temporarily) a black hole that has the mass (and thus gravitational pull) of two protons, with an electric charge of +2.
Not true, or at least not the way you mean. Each of the protons going into the collision carries its rest mass, but also the extra mass due to the fact it's moving at almost light-speed. In the case of the LHC this is about 10000 times greater, so you end up with a black hole with the mass of roughly 20002 protons (and, indeed charge +2).
Really nice for laptop users. Dump laptop on desk, plug in two cables (power and displayport) and have your whole desktop setup connected.
Be nice if displayport could also supply 100W or so of DC power.
Steve
This problem was solved a few years ago. Look up ClearCurve. They clad the fibre in tiny reflectors that recover the stray signal.
They are also using the Dollars to buy real assets -- land, mineral rights, businesses, in the US and elsewhere.
Assuming their technology is advanced, but not magic -- ie they are working within the physical laws as we understand them, then they still have to obey conservation of energy and dump waste heat somehow. The colder the temperatures they, or their machines, work at, the larger they can make the sphere and the longer the wavelength of the dumped heat but it still comes out somewhere. If they were so numerous as to be very much of the dark matter, they'd show up as a pattern in the cosmic microwave background, (since we know where the dark matter is) and they don't.
if someone managed to build a Dyson sphere around their star to harvest all of it's solar output, we wouldn't see that star. Just like you can't see a match when it's in a box. Possibly the only way to detect it would be via its gravity.
Not so. The Dyson sphere would reradiate all the star's output as waste heat at whatever temperature the inhabitants liked to live. It would look like a large infrared giant, instead of a small yellow star.
Wouldn't help much. Nuclear explosions aren't nearly powerful enough to get to relativistic velocities.
The units are appropriate. What this says is that to get the shuttle to that speed (assuming perfect efficiency) we need as much energy as all the sunlight that hits Earth in 10^4 seconds (about 3 hours). In other words, a lot, but not a completely silly amount.
If we convert that energy to mass, we see that we need about 10^4 kg, ie about 5 tons of anti-matter and 5 tons of matter, somehow combined and used as propellant with perfect efficiency.
I don't get it! Surely their perspective of the time to get there must be longer than it would take light to get there if they are travelling at Sub Light speeds? Our perspective may well see it as even longer, but they can't get there in less time than light if they travel slower than light?
Or maybe I need to pick up a Relativity Made Easy book ...
Maybe you do. From their perspective what their engines are doing is accelerating and then "squashing" the universe along the direction of thrust. They see 61 Virginis approaching them at almost light-speed, for most of the flight, but, in the middle, they measure the distance from the sun to 61V as significantly less than 28 ly. No one ever overtakes a light beam or sees anything else do so.
No, really not.
All self-contained propulsion systems (chemical, ion, nuclear pulse, fusion rocket,whatever)
basically do the same job: convert part of the rest mass of the rocket into kinetic energy of the rocket (as seen from Earth).
Then to stop you have to do the same job again, as seen from the frame of reference comoving with the rocket at top speed.
To get to relativistic velocities, where you experience time dilation,
you have to covert most of the rest mass into energy and efficiently transform all of that into KE.
This rules out fission and even fusion as power sources. You have to use antimatter, and quite a lot of it (as a proportion of your launch mass).
Nothing else is power- dense enough.
Non self-contained systems are easier -- laser propelled light-sails; beam propelled magsails; gravity catapults.
Have you a reference for that? It was certainly talked about, but I never heard of it being done.
While energy is equivalent to mass, that does not imply mass conversion is the only source of energy.
Batteries do not lose mass as they discharge.
Steve
It does and they do -- just not very much.
I did read that article. It didn't answer the question. The quantum vacuum consists of (at the energy levels we're dealing with) virtual photons. If we're giving net momentum to these virtual photons I think that is the same thing as there being real photons travelling in the appropriate direction. So, you move some charges and magnetic dipoles around, and you photons start moving -- how is this different from emitting something from an antenna?
And all electromagnetic forces are carried by photons so there isn't a difference in strength.
Is dumping momentum into the quantum vacuum different from emitting photons carrying the same momentum? If not, this is just a photon drive, which is a well known concept, has brilliant specific impulse but is incredibly energy-inefficient except at high relatavistic velocities.
OK "Every" was careless, but neither of the studies you mention shows any sign of being peer-reviewed. The first one, which I flicked through briefly offers no detailed information about its data selection or analysis.
I still maintain that the weight of evidence is overwhelmingly in favour of AGW and the need to act on emissions.
The more science is viewed with skepticism the better the science will be in my opinion.
Fair enough, but sometimes you have to make a decision now, based on what you know now. If you allow your "skepticism" to turn into "I'll make decisions based on the theory that is most personally convenient to me, even if the current evidence, while not conclusive, weighs against it" then you are not just being skeptical, you're being foolish.
Every serious scientific review that has looked at the evidence carefully (and at the raw data and at the analysis procedures, etc.) has concluded that the balance of evidence strongly supports AGW and strongly supports action now to curb emissions.
It is possible that in ten years time the balance of evidence will shift (or even tomorrow) but for the decisions we have to make today, that is irrelevant.
Why do you assume that liberals don't understand reality and you do? Maybe their theories are more accurate and complete than yours.
Climate Science is a STUDY, much like Social Studies, Political "Science", and most (but not all) fields of Psychology. You cannot experiment on Climate on the timeframes or scales these "scientists" are suggesting. You cannot produce a hypothesis, alter variables, and confirm or deny your ideas.
Would you also call astronomy "star studies"?
the global decrease in MEASURED temperatures
What decrease -- citation please?
Don't know about kickbacks etc., but do you have an alternative to stabilizing atmospheric CO2?