Oh my goodness - did I waste money buying those Low-E windows with the Titanium thin layer coating?
Probably not. Consider that the sunlight you'd be shielding against has a blackbody temperature of around 6000K, and then consider how much more quickly heat would get through those windows if there was a 6000K fluid on the other side. Radiation is extremely inefficient compared to conduction or convection, but that doesn't mean it can't transfer a lot of heat in certain circumstances.
Why make confusion with heliosphere if you yourself admitted it doesn't matter?
Well, initially I was simply trying to clarify the misconception that space near Earth is at a low temperature -- it isn't, any more than it's completely empty. And yes, the effective equilibrium temperature* would be a little above the CMB temperature, but only if you ignore sunlight (rather important, since that can make the difference between cooling to near CMB temperature and heating to hundreds of kelvins) and besides, it would take a very long time to reach equilibrium. The thread began with the need for insulation, but heat transfer (except for a negligible amount due to particle collissions) will not occur by conduction. Hence, no need for lots of insulation. The only way for a spacecraft to give up significant amounts of heat is by radiating it as light. Once on Pluto, or any other surface, however, the temperature makes a big difference since conduction is orders of magnitude more efficient at transfering heat than blackbody radiation.
*Technically, by the Zeroth Law of Thermodynamics, two bodies are in equilibrium if and only if they are at the same temperature, so equilibrium would be at the heliosphere temperature. As a practical matter, though, the heliosphere transfers so little heat that even blackbody radiation outpaces it.
Actually, I should clarify the CMB part, since I got a little sloppy in the wording (need sleep). It's not the average temperature of all matter in the universe, but closer to the temperature of space itself. More exactly, CMB photons permeate all space (unless shielded from them) and therefore roughly give even 'empty' space a temperature of ~2.7K. i.e., a blackbody in otherwise empty space shielded from other light sources would eventually heat or cool to ~2.7K.
That's not the temperature of the interstellar medium, it's the temperature of the cosmic background radiation -- they are completely different. I can see where the confusion could come from, though. Short version:
Cosmic Microwave Background: The residual heat of the big bang, redshifted (cooled) by ~13 billion years of expansion. This temperature is given in terms of the Stefan-Boltzmann relation (blackbody temperature), and basically represents the average temperature of the whole universe, including the vast, cold, empty intergalactic regions.
Interstellar Medium: A very diffuse (though still dense compared to the intergalactic regions) cloud of ionized gas filling the whole galaxy. These ionized particles move around very quickly, i.e., they're very hot (Maxwell-Boltzmann distribution). 7000K +/- 2000K according to this synopsis, at least for regions near the heliosphere.
Heliosphere: The gaseous bubble surrounding the sun out to about 100AU (Voyager 1 hit the termination shock where it meets the ISM at 94AU). It's hotter and denser than the interstellar medium, and it's where any space probe we launch would be travelling. Of course, since there is so little gas in even the heliosphere (its pressure would be considered a hard vacuum on Earth), these temperatures have very little effect on any spacecraft.
Actually, the electronics needs to work also during the trip, where the temperature is about 2.7 K.
Not really. The temperature of the heliosphere is actually rather high -- don't remember exactly offhand, but it's higher than the interstellar medium, which is somewhere around 7000K (give or take a couple thousand Kelvins). It's just that it stores almost no heat, since there's so little matter. (This is slightly sloppy wording, but close enough.) The upshot is that there is almost no heat conduction in either direction and almost all heat transfer occurs by blackbody radiation, which is amazingly inefficient. Even though Pluto doesn't have an atmosphere, touching the surface changes this entirely by providing a material to transfer heat to -- that's why a probe landing on Pluto would need a lot of insulation that a non-landing probe (e.g., V'ger) wouldn't.
Indeed they did, but that still required subluminal separation of the entangled particles. Basically (very basically - this is only a rough summary), for quantum teleportation, you need to entangle the particles and move them apart normally in order to create the 'transmit' and 'receive' points. That still allows superluminal teleportation later, but there's a major catch: the Bell state can be rotated by the event, and it requires sending classical information about the initial Bell state to account for this. To use the traditional example, if Alice sent a particle to Bob with a known initial Bell state (the entanglement relationship between the sent particle and her 'transmission' particle), Bob has to know the result of Alice's Bell state measurement in order to get any information about the sent particle. Otherwise, the no-communication theorem would be circumvented. IOW, you can teleport something, but its information and usefulness still travel no faster than light.
Of course, the big problem with quantum teleportation is that it requires coherent quantum states for entanglement - good luck doing that with a human (even a dead one). IIRC, C70 fullerenes (buckyballs) are around the current experimental upper cutoff for coherence.
By several years. So now there's more experimental evidence of accelerating expansion, but there's been evidence around for years. Just a few examples:
And not to put too fine a point on it, but here's a quote from Living with Lambda, written 7 years ago:
Recent supernovae results (Perlmutter et al 1998, Riess et al 1998) have made a strong case for a nonzero and possibly quite large cosmological constant.
Slashdot: news for nerds, almost a decade late.
FWIW, there are alternatives to a cosmological constant to explain the observed acceleration, such as new gravitational physics, variable speed of light, or Cardassian expansion (let the Star Trek jokes begin), but if you click through, you'll see that most of these face their own problems. I think a varying fine-structure constant has been proposed to explain the supernova observations, but it's no good for the others.
Disclaimer: IANAP, merely an undergrad astrophysics student who reads way too many papers on the arXiv. Linking to a paper does not necessarily imply endorsement of everything in it. YMMV and all that.
Special disclaimer on VSL: I haven't kept very current on this topic, so I don't really know whether I'm missing some serious problems about it's use to explain cosmological acceleration (beyond the thorny issues you run into when you lose Lorentz invariance or when c deviates far from 1).
presumably, given entanglement [wikipedia.org], measurement of qbit state allows potentially for instant communication ?
No, it doesn't. The closest you can come is instant synchronization of states, but you don't get to choose what state that is. For example, you can have two particles entangled to have the same (or opposite, as in the EPR thought experiment) spin orientation, but you can't send a signal from one to the other by choosing the orientation. Instead, it's random whether each one is spin up or spin down - the only guarantee is the relationship between the measurements. This would be great for things like cryptographic key exchange, since you can't have a man-in-the-middle attack if there is no middle, but it's useless for sending information. See: The No-Communication Theorem (warning: requires crazy math skills to avoid the MEGO effect)
nothing can travel faster than light.
I call bullshit. Relativity prohibits* local superluminal motion; non-locally, it's fair game. See, for example, the Alcubierre Warp Drive - the only question of whether it's possible or not (aside from new physics) rests on whether there's any local superluminal energy propagation at the edge of the spacetime bubble. Plus, QM allows for lots more in the way of non-local effects (even if you assume hidden variables, since Bell's Theorem rules out local hidden variables based on current experimental results), though, as I noted above, it still doesn't allow for superluminal communication (or teleportation, for that matter).
* Minor caveat: this is not counting tachyons, since nobody knows if they exist.
Not sure about GEO600, but the LIGO interferometer uses a simple solution: build two observatories on opposite sides of the country, and if only one detects a signal, it's almost certainly spurious. I'm guessing that since TFA says GEO600 will come online at the same time, it'll just be treated as another part of the same array for those purposes.
If you RTFA, you'll see that they spell it out. Short version: they send a big ol' block of metal (Hidalgo) hurling through space and slam it into a rock. Or, as they say in TFA:
Don Quijote is a NEO deflection test mission based entirely on conventional spacecraft technologies. It would comprise two spacecraft - one of them (Hidalgo) impacting an asteroid at a very high relative speed while a second one (Sancho) would arrive earlier at the same asteroid and remain in its vicinity before and after the impact to measure the variation on the asteroid's orbital parameters, as well as to study the object.
You have to actually carry out field tests. Generally this means you develop a simulated agent that is less dangerous than the real thing, calibrate it against the live agent in a sealed chamber**, and then conduct full-scale field trials with the simulant.
Cities were unwittingly used as laboratories to test aerosolization and dispersal methods; Aspergillus fumigatus, B. subtilis var. globigii, and Serratia marcescens were used as simulants and released during experiments in New York City, San Francisco, and other sites. Concerns regarding potential public health hazards of simulant studies were raised after an outbreak of nosocomial S. marcescens (formerly Chromobacterium prodigiosum) urinary tract infections at Stanford University Hospital between September 1950 and February 1951, following covert experiments using S. marcescens as a simulant in San Francisco. A report from the Centers for Disease Control completed in 1977 found no association between reported morbidity and mortality from pneumonia and influenza and local simulant experiments.
A series of field tests took place under the auspices of the Biological Laboratories from 1943 to the mid-1960s:
In one such test, travelers at Washington National Airport were subjected to a harmless bacterium. Traps were placed throughout the facility to capture the bacterium as it flowed in the air. Laboratory personnel, dressed as travelers carrying brief cases, walked the corridors and without detection sprayed the bacterium into the atmosphere.
In the New York Subway, a light bulb filled with the same harmless bacterium was dropped on the tracks. The organism spread throughout the system within 20 minutes. Traps and monitoring devices showed the amount of organism--if it were one of the predictable, dangerous organisms, could have killed thousands of persons. No one was injured or became ill as a result of the test.
In San Francisco, a U.S. Navy ship, equipped with spray devices operated by Fort Detrick personnel, sprayed serratia marcescens, a non-pathogenic microorganism that is easily detected, while the ship plied the San Francisco Bay. It spread more than 30 miles to monitoring stations.
A jet aircraft equipped with spray devices, flew a course near Victoria, Texas, and the harmless particles were monitored in the Florida Keys.
Also, USAMRIID seems to be strong evidence against the need for this as a 'defensive' action, since they already conduct such testing. The difference is, USAMRIID is open to civilian researchers (from, e.g., CDC or WHO), whereas the Dugway Proving Grounds are not, and have a long history of offensive C/BW research:
In March 1968, 6,400 sheep were found dead after grazing in south Skull Valley, an area just outside Dugway's boundaries. When examined, the sheep were found to have been poisoned by a deadly nerve agent called VX.
And if you RTFA, you'll see that Dugway was known to be manufacturing lethal anthrax as recently as 1998. Really, the only semi-plausible reason for them to buy so much anthrax growing equipment and put it out there is for testing "agent defeat" warheads, but I have a sneaking suspicion that's a euphamism for tactical nuclear weapons.
Sorry to break it to you, but Ambassador James Leonard, who negotiated the BWC treaty on behalf of President Nixon, isn't buying that argument. See this short article (warning: PDF, but only 4 pages). In case it gets/.'d, here's the important part:
The rapidity of elaboration of American biodefense programs, their ambition and administrative aggressiveness, and the degree to which they push against the prohibitions of the Biological Weapons Convention (BWC), are startling.
The production and stockpiling of biological-weapons agents are not the only criteria by which an offensive biological weapons (BW) program is defined. They are only such a program's most obvious terminal expressions. Taken together, many of the activities detailed above -- most particularly the "Store, Stabilize, Package, Disperse" sequence and the "Computational modeling of feasibility, methods, and scale of production" item -- may constitute development in the guise of threat assessment, and they certainly will be interpreted that way. Development is prohibited by the Biological Weapons Convention.
Actually, even their phenotype (expressed genetics) might be different from the original due to environmental influences. This is practically guaranteed for female clones because they have a lot of extra genetic material in the second X chromasome that gets turned off during gestation. This can lead to some rather stark contrasts between 'originals' and clones - e.g., cloned cats with different color patterns. For instance, CC is a tiger-tabby because her surrogate mother, not the original (a calico), was.
Slashdot Mirror
*Technically, by the Zeroth Law of Thermodynamics, two bodies are in equilibrium if and only if they are at the same temperature, so equilibrium would be at the heliosphere temperature. As a practical matter, though, the heliosphere transfers so little heat that even blackbody radiation outpaces it.
Actually, I should clarify the CMB part, since I got a little sloppy in the wording (need sleep). It's not the average temperature of all matter in the universe, but closer to the temperature of space itself. More exactly, CMB photons permeate all space (unless shielded from them) and therefore roughly give even 'empty' space a temperature of ~2.7K. i.e., a blackbody in otherwise empty space shielded from other light sources would eventually heat or cool to ~2.7K.
Bah. I should just leave well enough alone.
"National Socialist Workers" party sound familiar at all to you?
"Democratic People's Republic of Korea" sound familiar at all to you?
Same thing I was thinking... would programmers with Klinefelter's syndrome solve the problem?
Not sure if the toolkit is available stand-alone (doubt it), but there most certainly is a Linux version of NWN.
Stupid moderators... click through, morons. That should be "funny" not "insightful".
"Erwin, what did you do to the cat? The poor thing is half-dead!"
Indeed they did, but that still required subluminal separation of the entangled particles. Basically (very basically - this is only a rough summary), for quantum teleportation, you need to entangle the particles and move them apart normally in order to create the 'transmit' and 'receive' points. That still allows superluminal teleportation later, but there's a major catch: the Bell state can be rotated by the event, and it requires sending classical information about the initial Bell state to account for this. To use the traditional example, if Alice sent a particle to Bob with a known initial Bell state (the entanglement relationship between the sent particle and her 'transmission' particle), Bob has to know the result of Alice's Bell state measurement in order to get any information about the sent particle. Otherwise, the no-communication theorem would be circumvented. IOW, you can teleport something, but its information and usefulness still travel no faster than light.
Of course, the big problem with quantum teleportation is that it requires coherent quantum states for entanglement - good luck doing that with a human (even a dead one). IIRC, C70 fullerenes (buckyballs) are around the current experimental upper cutoff for coherence.
- Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
- Measurements of Omega and Lambda from 42 High-Redshift Supernovae (note: Omega refers to, roughly speaking, universal mean energy density and Lambda the cosmological constant)
- First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
- New Constraints on Omega_M, Omega_Lambda, and w from an Independent Set of Eleven High-Redshift Supernovae Observed with HST
- A measurement of Omega from the North American test flight of BOOMERANG (includes observational constraints on Lambda)
And not to put too fine a point on it, but here's a quote from Living with Lambda, written 7 years ago: Slashdot: news for nerds, almost a decade late.FWIW, there are alternatives to a cosmological constant to explain the observed acceleration, such as new gravitational physics, variable speed of light, or Cardassian expansion (let the Star Trek jokes begin), but if you click through, you'll see that most of these face their own problems. I think a varying fine-structure constant has been proposed to explain the supernova observations, but it's no good for the others.
Disclaimer: IANAP, merely an undergrad astrophysics student who reads way too many papers on the arXiv. Linking to a paper does not necessarily imply endorsement of everything in it. YMMV and all that.
Special disclaimer on VSL: I haven't kept very current on this topic, so I don't really know whether I'm missing some serious problems about it's use to explain cosmological acceleration (beyond the thorny issues you run into when you lose Lorentz invariance or when c deviates far from 1).
presumably, given entanglement [wikipedia.org], measurement of qbit state allows potentially for instant communication ?
No, it doesn't. The closest you can come is instant synchronization of states, but you don't get to choose what state that is. For example, you can have two particles entangled to have the same (or opposite, as in the EPR thought experiment) spin orientation, but you can't send a signal from one to the other by choosing the orientation. Instead, it's random whether each one is spin up or spin down - the only guarantee is the relationship between the measurements. This would be great for things like cryptographic key exchange, since you can't have a man-in-the-middle attack if there is no middle, but it's useless for sending information. See: The No-Communication Theorem (warning: requires crazy math skills to avoid the MEGO effect)
nothing can travel faster than light.
I call bullshit. Relativity prohibits* local superluminal motion; non-locally, it's fair game. See, for example, the Alcubierre Warp Drive - the only question of whether it's possible or not (aside from new physics) rests on whether there's any local superluminal energy propagation at the edge of the spacetime bubble. Plus, QM allows for lots more in the way of non-local effects (even if you assume hidden variables, since Bell's Theorem rules out local hidden variables based on current experimental results), though, as I noted above, it still doesn't allow for superluminal communication (or teleportation, for that matter).
* Minor caveat: this is not counting tachyons, since nobody knows if they exist.
No. No it is not. The first and only time in /. history a GNAA reference was not off topic was here: Ask Slashdot: What's the Worst Movie You've Ever Seen?
Not sure about GEO600, but the LIGO interferometer uses a simple solution: build two observatories on opposite sides of the country, and if only one detects a signal, it's almost certainly spurious. I'm guessing that since TFA says GEO600 will come online at the same time, it'll just be treated as another part of the same array for those purposes.
Not Cheetos... Funyons.
That makes more sense if you remember this story.
I suggest you blow up Earth and speed up our process to go to Mars.
Yeah, and get cracking - geocide is hard work!
Actually, even their phenotype (expressed genetics) might be different from the original due to environmental influences. This is practically guaranteed for female clones because they have a lot of extra genetic material in the second X chromasome that gets turned off during gestation. This can lead to some rather stark contrasts between 'originals' and clones - e.g., cloned cats with different color patterns. For instance, CC is a tiger-tabby because her surrogate mother, not the original (a calico), was.