Black holes are not infinitely dense (caveat, volume may not make too much sense for a black hole if you get pedantic). A black hole with the same mass as the sun would (roughly speaking) be a sphere about 4 miles in diameter. Any light actually hitting that sphere would be absorbed. Light just barely missing it will be bent through large angles. Light passing a few miles away will be bent through smaller angles and so on. If you're in the right place, this can make make something behind the black hole look a bit brighter, because more of the light from it gets to you.
Dark matter is not especially dense anywhere (we think). It's spread throughout galaxies and clusters of galaxies like a sort of background haze. Actually, given the relative amounts it's better to say the Universe is full of a web of sheets and filaments of dark matter. At a few places where this is especially dense it has attracted (by gravity) enough normal matter to form a large black hole and its accompanying galaxy.
From the way it clumps around galaxies and clusters of galaxies, I think we know that it isn't moving at or close to the speed of light, which rules out gravitons and a bunch of other things.
Looking longer and longer by the day. Aether was invented because people felt it SHOULD exist, but expected consequences of it completely failed to show up. Dark matter was invented because there were observations that are very hard to explain any other way and fit increasingly precisely with one another if dark matter is the cause -- there are several different ways of measuring the distribution of dark matter among various clusters of galaxies, and they are giving remarkably consistent answers.
A better example would be phlogiston, which was invented to explain observations, but eventually failed to explain all observations, so it was replaced by a better theory. The same could happen to dark matter, but there are no signs at the moment,
As I understand it calling it dust is technically a misnomer. Experts use the term "fines". Calling this stuff dust is like called fine talc gravel, except worse.
The nice thing is you only need to look at it if anything goes wrong -- a book is missing or damaged, for instance. Otherwise, people carry on using the paper system they're used to. As for storage, a 1TB disk should hold a year or so no problem.
But it works equally well for the artists if every fan pays $100 and possesses digital copies of 10000 tracks or if they pay $100 and possess copies of 10 tracks. The idea that everyone owns "tens of thousands of dollars worth" of music is based on an an artificial idea of what music is worth. Yes, for the sake of argument, artists need to be compensated, somehow, but that doesn't mean you have to pay some huge price for every piece of art you happen to store a copy of.
The attraction is the ability to study a steady stream of asteroidal rocks extremely cheaply. Bigger rocks either don't come along as often or don't come as close (close in the sense of the amount of fuel needed to reach them). The only exception is the Moon, which is (a) just one rock and (b) so big that you need significant fuel to land on it and take off again.
Assuming you're talking unmanned, which seems likely, a mission to lurk somewhere suitable and study (and perhaps "tag" with a radar reflector) as many of these rocks as possible over say a 10-20 year period would cost comparatively little and we'd get to see a significant number of different samples of the local population of rocks. This would let us make reasonably solid deductions about the material the Earth formed from, which could have all kinds of applications.
We'd also get a number of probes into the way things move around the complex Earth-sun-moon dynamics, which would be interesting and might also help plan future unmanned space missions, or divert future larger rocks.
At the cost of slightly perturbing the orbits, couldn't you "harpoon" them with a transponder (or laser reflector) on a penetrator? Probably only needs to mass a few kg, could be launched from LEO by a modest solid fuel booster, and would just need a very small thrusters to make sure it hit point first. We can track the missile and the target with radar from here, aim for an impact velocity enough to lodge a hardened spike in rock.
The much more difficult mission is to recover one. One approach would be to wrap the rock in some kind of ablative heat shield and then put it on a trajectory to impact in shallow water somewhere. If you don't mind waiting a few months or years for the impact it shouldn't need much delta-V. More challenging would be to try and capture it in LEO and then bring it down in a Dragon or Soyuz.
Unless the lecturers are willing to change their style quite a bit I don't think you'll do well without a cameraman in the room. In my experience lecturers move around quite a lot, and sometimes you need to pull back to get their body language, at other times you need to zoom in on the black- or white-board to see what they are writing or pointing at.
There are some reasons. If you assume that life is based on complex chemistry in the first place (and not say magnetic fields in a gas cloud or electrostatic patterns in clay or naturally evolved electronic circuits or.... -- and here the looking under the streetlight theory applies) then there are surprisingly few choices. To have complex chemistry you need the possibility of lots of kinds of large molecules. Metals don't do that, so you are down to non-metals. If you have mostly atoms that form 1 or 2 chemical bonds each they can't make a large molecule except a simple chain (sulphur makes chains like this, for instance) and there isn't enough choice. That eliminates halogens, oxygen. sulphur, noble gases, hydrogen,... leaving basically nitrogen, phosphorous, carbon, silicon and maybe germanium and antimony. Although nitrogen could make large molecules in principle, the NN triple bond is so stable that these molecules fall apart into nitrogen gas. Phosphorous, silicon and the rest prefer to bond with oxygen than each other. Complex phospenes and silanes might be possible in the absence of oxygen especially at low temperatures, but oxygen is a more common element than phosphorous or silicon, so this seems unlikely (although not impossible). That leaves carbon.
Probably next plausible possibility is large molecules where the "backbone" is alternating silicon and oxygen atoms. This makes quite stable silicone polymers, with scope for a wide variety of structures.
The atmosphere is mostly CO2, there is relatively little hydrogen (although obviously some in the sulfuric acid clouds. Also it's at the bottom of a pretty deep gravity well. You're better off mining ice on Mars and splitting it with solar or nuclear power, or even seawater from Earth. Apart from research, Venus seems like a remarkably useless planet so far.
Basic question is what you mean by "colony". My personal guess is that what you will get are initially expeditions where a few humans visit, do research, leave instruments and go home. After that you get "mining camps" -- long-lived outposts where humans are based for a few years to do jobs that can't be done by robots managed from Earth. The ISS is a very minimal example of this in LEO. If the work is producing sufficient return (in science or good or whatever) then these camps gradually expand as it becomes convenient to base people there for longer and to make them less dependent on services from Earth. Eventually you get something which actually can survive on its own and trade with Earth on a more equal basis.
The moon is surely the first target for expeditions, followed by near-Earth asteroids, then the moons of Mars, then Mars itself, then maybe more distant asteroids. Which, if any, of these ever progress to the "mining camp" stage depends on what is discovered. We might want to mine the moon for He3 or for mass for orbital construction, but it's fairly easy to teleoperate machinery on the moon from here.
Asteroids might be targets for actual mining, aiming to shop back metals carbon and (maybe) volatiles to Earth orbit, or even eventually to Earth. The problem is that they are very spread out. There's no obvious place to have a colony or camp which is more convenient for very many asteroids than Earth is.
Mars might be a source of volatiles (ice) for Earth orbit, or a research target -- for example if life, or clear evidence of complex past life was found.
Everywhere else is really too far away and/or too hostile to be a near future target.
In this chart, that's true. Of course the underlying raw data might show more than the chart. From what I've read elsewhere, I'm pretty sure it doesn't show any values as high as present values.
That chart is too coarse-grained, in the time dimension to show the recent very sharp peak. The CH4 peaks (including the "present" one) on that chart are at about 0.7 ppm and the current level is about 1.7. Similarly, the CO2 peaks are at about 280 ppm and the current level is around 385.
As for biological factors, It seems to me the distribution curve for men is flatter than for women in most things. You get more insane/evil/retarded men than women. You also get more "ultra genius" men than women.
This is one of the hypotheses explored in the study. They find no support for it.
Several scientists have described schemes for manned insterstellar missions. They do use huge amounts of power, and are not likely to be practical for a century or two, but the sun produces a LOT of power which could be harvested.
However, what is really surprising if technological life is at all common in the galaxy is that no one has felt inclined to send out self-replicating robot probes or "spam" the galaxy with radio or laser messages. Robot probes travelling at even 0.1% of light speed would span the galaxy in a couple of hundred million year, a tiny fraction of its age, while laser or radio messages would take less than a million years.
We decided we couldn't outsource staff email to google or anyone like that, but student email was fine. We do now outsource staff email, but it's on dedicated servers (which I think we legally own).
The X-rays will certainly heat the sample very rapidly indeed, and thereby probably increase the pressure in the cell, at least briefly, so I don't think the article is all wrong. Probably better to think of the diamond anvil cell as a pre-pressurizing step.
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Black holes are not infinitely dense (caveat, volume may not make too much sense for a black hole if you get pedantic). A black hole with the same mass as the sun would (roughly speaking) be a sphere about 4 miles in diameter. Any light actually hitting that sphere would be absorbed. Light just barely missing it will be bent through large angles. Light passing a few miles away will be bent through smaller angles and so on. If you're in the right place, this can make make something behind the black hole look a bit brighter, because more of the light from it gets to you.
Dark matter is not especially dense anywhere (we think). It's spread throughout galaxies and clusters of galaxies like a sort of background haze. Actually, given the relative amounts it's better to say the Universe is full of a web of sheets and filaments of dark matter. At a few places where this is especially dense it has attracted (by gravity) enough normal matter to form a large black hole and its accompanying galaxy.
From the way it clumps around galaxies and clusters of galaxies, I think we know that it isn't moving at or close to the speed of light, which rules out gravitons and a bunch of other things.
Looking longer and longer by the day. Aether was invented because people felt it SHOULD exist, but expected consequences of it completely failed to show up. Dark matter was invented because there were observations that are very hard to explain any other way and fit increasingly precisely with one another if dark matter is the cause -- there are several different ways of measuring the distribution of dark matter among various clusters of galaxies, and they are giving remarkably consistent answers.
A better example would be phlogiston, which was invented to explain observations, but eventually failed to explain all observations, so it was replaced by a better theory. The same could happen to dark matter, but there are no signs at the moment,
As I understand it calling it dust is technically a misnomer. Experts use the term "fines". Calling this stuff dust is like called fine talc gravel, except worse.
The nice thing is you only need to look at it if anything goes wrong -- a book is missing or damaged, for instance. Otherwise, people carry on using the paper system they're used to. As for storage, a 1TB disk should hold a year or so no problem.
Just put a webcam where it can see people taking and removing books and record low-rate video.
No one has to change what they do, but you have a record if a book is not returned.
But it works equally well for the artists if every fan pays $100 and possesses digital copies of 10000 tracks or if they pay $100 and possess copies of 10 tracks. The idea that everyone owns "tens of thousands of dollars worth" of music is based on an an artificial idea of what music is worth. Yes, for the sake of argument, artists need to be compensated, somehow, but that doesn't mean you have to pay some huge price for every piece of art you happen to store a copy of.
The attraction is the ability to study a steady stream of asteroidal rocks extremely cheaply. Bigger rocks either don't come along as often or don't come as close (close in the sense of the amount of fuel needed to reach them). The only exception is the Moon, which is (a) just one rock and (b) so big that you need significant fuel to land on it and take off again.
Assuming you're talking unmanned, which seems likely, a mission to lurk somewhere suitable and study (and perhaps "tag" with a radar reflector) as many of these rocks as possible over say a 10-20 year period would cost comparatively little and we'd get to see a significant number of different samples of the local population of rocks. This would let us make reasonably solid deductions about the material the Earth formed from, which could have all kinds of applications.
We'd also get a number of probes into the way things move around the complex Earth-sun-moon dynamics, which would be interesting and might also help plan future unmanned space missions, or divert future larger rocks.
At the cost of slightly perturbing the orbits, couldn't you "harpoon" them with a transponder (or laser reflector) on a penetrator? Probably only needs to mass a few kg, could be launched from LEO by a modest solid fuel booster, and would just need a very small thrusters to make sure it hit point first. We can track the missile and the target with radar from here, aim for an impact velocity enough to lodge a hardened spike in rock.
The much more difficult mission is to recover one. One approach would be to wrap the rock in some kind of ablative heat shield and then put it on a trajectory to impact in shallow water somewhere. If you don't mind waiting a few months or years for the impact it shouldn't need much delta-V. More challenging would be to try and capture it in LEO and then bring it down in a Dragon or Soyuz.
Unless the lecturers are willing to change their style quite a bit I don't think you'll do well without a cameraman in the room.
In my experience lecturers move around quite a lot, and sometimes you need to pull back to get their body language, at other times you need to zoom
in on the black- or white-board to see what they are writing or pointing at.
There are some reasons. If you assume that life is based on complex chemistry in the first place (and not say magnetic fields in a gas cloud or electrostatic patterns in clay or naturally evolved electronic circuits or .... -- and here the looking under the streetlight theory applies) then there are surprisingly few choices. To have complex chemistry you need the possibility of lots of kinds of large molecules. Metals don't do that, so you are down to non-metals. If you have mostly atoms that form 1 or 2 chemical bonds each they can't make a large molecule except a simple chain (sulphur makes chains like this, for instance) and there isn't enough choice. That eliminates halogens, oxygen. sulphur, noble gases, hydrogen,... leaving basically nitrogen, phosphorous, carbon, silicon and maybe germanium and antimony. Although nitrogen could make large molecules in principle, the NN triple bond is so stable that these molecules fall apart into nitrogen gas. Phosphorous, silicon and the rest prefer to bond with oxygen than each other. Complex phospenes and silanes might be possible in the absence of oxygen especially at low temperatures, but oxygen is a more common element than phosphorous or silicon, so this seems unlikely (although not impossible). That leaves carbon.
Probably next plausible possibility is large molecules where the "backbone" is alternating silicon and oxygen atoms. This makes quite stable silicone polymers, with scope for a wide variety of structures.
Any reason to believe ORNL aren't using the heat from their supercomputers for offices or whatever?
But battery swaps would work great for a taxi -- you're usually close to base and have competent drivers and even competent staff at the base.
The article says 2.2MW, which is roughly 2W/GFLOP.
The atmosphere is mostly CO2, there is relatively little hydrogen (although obviously some in the sulfuric acid clouds. Also it's at the bottom of a pretty deep gravity well. You're better off mining ice on Mars and splitting it with solar or nuclear power, or even seawater from Earth. Apart from research, Venus seems like a remarkably useless planet so far.
Basic question is what you mean by "colony". My personal guess is that what you will get are initially expeditions where a few humans visit, do research, leave instruments and go home. After that you get "mining camps" -- long-lived outposts where humans are based for a few years to do jobs that can't be done by robots managed from Earth. The ISS is a very minimal example of this in LEO. If the work is producing sufficient return (in science or good or whatever) then these camps gradually expand as it becomes convenient to base people there for longer and to make them less dependent on services from Earth. Eventually you get something which actually can survive on its own and trade with Earth on a more equal basis.
The moon is surely the first target for expeditions, followed by near-Earth asteroids, then the moons of Mars, then Mars itself, then maybe more distant asteroids.
Which, if any, of these ever progress to the "mining camp" stage depends on what is discovered. We might want to mine the moon for He3 or for mass for orbital construction, but it's fairly easy to teleoperate machinery on the moon from here.
Asteroids might be targets for actual mining, aiming to shop back metals carbon and (maybe) volatiles to Earth orbit, or even eventually to Earth. The problem is that they are very spread out. There's no obvious place to have a colony or camp which is more convenient for very many asteroids than Earth is.
Mars might be a source of volatiles (ice) for Earth orbit, or a research target -- for example if life, or clear evidence of complex past life was found.
Everywhere else is really too far away and/or too hostile to be a near future target.
Might also relate to larger climate cycles. The earlier part of this data would, if I recall correctly, come from before the last cluster of ice ages.
In this chart, that's true. Of course the underlying raw data might show more than the chart.
From what I've read elsewhere, I'm pretty sure it doesn't show any values as high as present values.
That chart is too coarse-grained, in the time dimension to show the recent very sharp peak. The CH4 peaks (including the "present" one) on that chart
are at about 0.7 ppm and the current level is about 1.7. Similarly, the CO2 peaks are at about 280 ppm and the current level is around 385.
As for biological factors, It seems to me the distribution curve for men is flatter than for women in most things. You get more insane/evil/retarded men than women. You also get more "ultra genius" men than women.
This is one of the hypotheses explored in the study. They find no support for it.
Several scientists have described schemes for manned insterstellar missions. They do use huge amounts of power, and are not likely to be practical for a century or two, but the sun produces a LOT of power which could be harvested.
However, what is really surprising if technological life is at all common in the galaxy is that no one has felt inclined to send out self-replicating robot probes or "spam" the galaxy with radio or laser messages. Robot probes travelling at even 0.1% of light speed would span the galaxy in a couple of hundred million year, a tiny fraction of its age, while laser or radio messages would take less than a million years.
Depleted uranium is barely radiioactive -- the half-life of U238 is billions of years. The problem is that it is a chemical poison.
We decided we couldn't outsource staff email to google or anyone like that, but student email was fine. We do now outsource staff email, but it's on dedicated servers (which I think we legally own).
That's your opinion, which you are rather close to trying to impose on others.
Other people take the view that it is ethical to encourage, or even compel others
to avoid some unethical behaviours, so they try to do that.
The X-rays will certainly heat the sample very rapidly indeed, and thereby probably increase the pressure in the cell, at least briefly, so I don't think the article is all wrong. Probably better to think of the diamond anvil cell as a pre-pressurizing step.