It is hypothesized that the "halo" of a spiral galaxy must either contain considerable unobserved "dark matter"...
It is not quite correct to say that the halo of a spiral galaxy must either contain considerable unobserved dark matter.
We can tell that the mass is there by the motion of the visible stars in the halo, which provides mass distribution maps. The gravity produced by dark matter is every bit as valid a means of detection as photons, or by mass inferred by the orbital rate of inner parts of globular clusters, or any other astrophysical context where gravitation is the means of observation.
Observations of the structure of the Universe, and efforts at modelling it, have demolished all alternative theories that try to dispense with dark matter as something real by this point. The filamentary structure of the Universe, the existence of dark matter dominated galaxies like Dragonfly 44 that have almost no baryonic matter, the mass distribution within the Local Cluster, and within the Milky Way itself, the dozen or so different lines of evidence we now have for dark matter's existence, all are consistent with this theory. Alternative theories like MOND can only be made to work in special cases, and fail generally.
Dark matter appears to be quite real. We just have no idea what is, or how to detect it other than by gravity.
Also one needs to note that they are talking about the the visible edge of the disk which is defined by where the disk star population ends. This is not the edge of galactic system as their is a massive halo of dark matter extending far out from the visible disk.
In the conclusion section of the paper they make the following key observation Continuous
cosmic accretion provides a natural explanation for the RV relation and is their preferred explanation, but the paper is not seeking to establish that.
When someone announces a specific, feasible plan for "uploading" the 302 neuron brain of a Caenorhabditis elegans marine worm I'll start paying attention. They won't even have to actually do it. I'll be happy with just the plan.
Until then all this talk of "uploading" a human consciousness is simply a faux-scientific religion -- a way to try to deny the finality of death.
Yep, pretty much. These videos come accompanied by a wall of hype about showing amazing things. But nothing amazing appears in the video. Same as the last one. It is always an object locked dead center in the camera, showing no sign of "maneuvering" and with the apparent motion quite possibly entirely due to parallax and the aircraft itself.
And this stuff is being pushed by a guy who is making money from this hype. This is a commercial venture, converting gullibility into cold hard cash legally. He is using his former status in the government to monetize his retirement.
The images created for the plaque were explicitly not intended to look like "two white people", and the female figure definitely has an Asian look to her. They both look a trifle pan-ethnic, given the level of detail.The dude's hair? Well, you do have a point there.
Despite the reflex skepticism, this announcement makes perfect sense. The Space X "Mars rocket" ifs the BFR, which standards for (so they say) "Big Falcon Rocket", the first stage of which has 31 engines. Testing that these 31 engines all work together, and testing failure modes, is really important before trying an actual full scale launch.
I am not bothering to watch the YouTube video (really, that's your "reference"?) but the rocket equation derived from Newton's laws of motion were first formulated in 1813 by William Moore, again by William Leitch in 1861, but most famously by Konstantin Tsiolkovsky in the early 1890s, and published in a well-known work in 1903.
This is all really well known.
So, no. you are profoundly ignorant about this subject. Sorry.
If you actually read the WIkipedia section you reference you will see that this "common belief" refers to a common popular (i.e. laymen's) belief as exemplified by an editorial by the New York Times editorial staff. Journalists have never been known for their scientific literacy.
This a very famous journalistic science blunder.
This post does absolutely nothing for your credibility.
Meanwhile, it would be very fitting for Google and other deep-pocketed corporations with an interest in a global Internet and more balanced copyright to help Gutenberg finance its battle.
Google has lost all interest in the original mission to which it once referred of making knowledge available to the world (along with its watch-phrase "Don't be evil").
The near-death of the Google Books project is the poster child for this. Google actually won the lawsuit that the Authors Guild had waged against it for putting books, with limited search of snippets, on Google Books, and Google has a millions of out of copyright, out of print books - virtually inaccessible to the world - that it has already scanned and can be put on Google Books in the entirety to make them available to the world any time it likes. But it has dropped plans to do that. Books are still being added I read, but at a slow pace - not a priority. There are an estimated 25 million such inaccessible books out there that could be scanned and added, doubling the size of Google Books.
Google losing interest in supporting public access to published works shows up in lots of ways. It stopped updated the Google Books history page in 2007, its books blog has disappeared, its really useful NGram viewer stopped updating in 2008.
(And lately it was one of the five principle corporate sponsors of the CPAC wingnut festival.)
I agree fully with your remarks. There seems no prospect that fusion is going produce cost-competitive energy.
However I would like to see them build a practical (though very expensive) power plant. That will be an important step for developing fusion for where will really need it some day in deep space. Not until sometime next century at the earliest - but we can make progress in that direction now.
But, like the pharaoh and his attempt to beat back the tide, it'll all be for nought as the Marketeers will win.
The legend is about King Cnut (or Canute) who was King of Denmark, England and Norway (recorded 150 years after his death) and presents the opposite of what people believe. The point was that the King was showing his fawning courtiers that he was merely mortal and could not hold back the tide.
Oddly, no links or actual numbers in your assertions. Almost as if you were just passing on Uber hype. That is really strange.
A little Googling, even filtering for recently dated reports, repeatedly lists Uber drivers in the U.S. doubling from 2014 to 2015 (which represents flattening percentage rate of growth year over year from its founding). No actual reports of U.S. drivers since that time (but lots of people trying to extrapolate from it, as if this was an established law of nature). So, maybe it has not been doubling over the last three years.
Also half of all Uber drivers quit within 12 months. Why would they do that if the pay isn't crap (to turn around your argument)?
Lots of people here fixated on Australian tables (I've visited, they have nice tables).
No discussion of any of the actual findings though.
So far Dark Matter appears to interact only through the gravitational force, even with itself.
If, as this study suggests, "only cooling of the gas as a result of interactions between dark matter and baryons seems to explain the observed amplitude" and that interaction is anything other than a purely gravitational one, it will be the first evidence of Dark Matter interacting at all except through gravity. That could make this a really big deal. In about five years the first phase of the Square Kilometer Array should be able to greatly expand our ability to investigate this.
One beef with the summary is that there currently is no such thing as fossil fuels with carbon capture technology. There is NO industrial scale carbon capture or carbon sequestration technology available nor any reasonable prospect of such technology in the near future. So take that off the table as an option until such time as it becomes a real thing.
True, but since it is only needed to cover that last 20%, when we are already have 80% wind and solar, it is not needed now. We are currently at 15%, and at a reasonable 4.5% annual growth rate in production we will get to 80% in about 40 years. We can cut it to about 30 years at 6% a year, but in any case we are few decades off of needing this technology to be ready.
It is normal for a technology that is not yet needed not to be already deployed.
The cost of that last 20% is steeper on a percentage basis, but the aggregate cost is definitely not more (much less "much more") than the aggregate cost of the first 80%.
And part of the solution is not to demand that only solar and wind be used. Nuclear should still be in the mix (licenses are available for any capitalist who wants to build one) for example. There are a lot of options that could cover that last 20% (biofuels, carbon capture, nuclear as cited) and competition and innovation will push us toward the lowest cost way of doing it.
This is the study I have been looking/waiting for that gives a realistic assessment of what the future power grid for North America (and Eurasia) should look like.
The summary cites the two different options for dealing with the intermittent nature of wind and solar -- power storage (which is the go-to assumption everyone makes as the only option), and having a low loss national power grid to distribute power efficiently, but inevitably it only cites the cost of the more expensive of the two -- power storage. The report itself gives an estimate for the national grid option and it is only $410 billion dollars vs >$1 trillion for the storage option. Over a 40 year period this amounts to an investment of $10 billion a year. Currently about $70 billion is invested annually in electricity production and transmission, so this is in line with current and projected levels of investment.
It will be quite awhile before we have to really worry about going from 80% wind and solar to 100% - do we want to, is it worth the cost? In the mean time gas peaking plants can plug some of this gap. But nuclear energy at its current scale, about 20% of capacity, fits in very nicely. Currently licensed stations are looking at getting their licenses extended to 80 years, so they can cover this out to 2045 or so.
Of course there are straightforward fixes to this, well known in much of the world. A single electronic debit card for all forms of public transportation, with "recharge" opportunities everywhere (so that you can convert cash, bank balances, and credit lines into transportation balances). All this requires is to deploy readily available, thoroughly proven Internet based technology. If they can sell you a lottery ticket they can recharge your trip card.
I used the Opal card when visiting Sydney, Australia and it was a breeze. I got all around the city with no trouble, and not terrific expense.
Slashdot Mirror
It is hypothesized that the "halo" of a spiral galaxy must either contain considerable unobserved "dark matter" ...
It is not quite correct to say that the halo of a spiral galaxy must either contain considerable unobserved dark matter.
We can tell that the mass is there by the motion of the visible stars in the halo, which provides mass distribution maps. The gravity produced by dark matter is every bit as valid a means of detection as photons, or by mass inferred by the orbital rate of inner parts of globular clusters, or any other astrophysical context where gravitation is the means of observation.
Observations of the structure of the Universe, and efforts at modelling it, have demolished all alternative theories that try to dispense with dark matter as something real by this point. The filamentary structure of the Universe, the existence of dark matter dominated galaxies like Dragonfly 44 that have almost no baryonic matter, the mass distribution within the Local Cluster, and within the Milky Way itself, the dozen or so different lines of evidence we now have for dark matter's existence, all are consistent with this theory. Alternative theories like MOND can only be made to work in special cases, and fail generally.
Dark matter appears to be quite real. We just have no idea what is, or how to detect it other than by gravity.
Also one needs to note that they are talking about the the visible edge of the disk which is defined by where the disk star population ends. This is not the edge of galactic system as their is a massive halo of dark matter extending far out from the visible disk.
In the conclusion section of the paper they make the following key observation Continuous cosmic accretion provides a natural explanation for the RV relation and is their preferred explanation, but the paper is not seeking to establish that.
Yeah. Voting Libertarian! That's the ticket! Look at all the good the many Libertarians in Congress have done! Or the Greens!
Maybe he looks like this?
A prince of a guy!
(People who use this expression seem to never have read The Prince .)
As I tell vendors, it isn't a backup until you can prove you can restore the data.
Bingo!
When someone announces a specific, feasible plan for "uploading" the 302 neuron brain of a Caenorhabditis elegans marine worm I'll start paying attention. They won't even have to actually do it. I'll be happy with just the plan.
Until then all this talk of "uploading" a human consciousness is simply a faux-scientific religion -- a way to try to deny the finality of death.
Appy is back!
I miss the cows mooing.
Yep, pretty much. These videos come accompanied by a wall of hype about showing amazing things. But nothing amazing appears in the video. Same as the last one. It is always an object locked dead center in the camera, showing no sign of "maneuvering" and with the apparent motion quite possibly entirely due to parallax and the aircraft itself.
And this stuff is being pushed by a guy who is making money from this hype. This is a commercial venture, converting gullibility into cold hard cash legally. He is using his former status in the government to monetize his retirement.
The images created for the plaque were explicitly not intended to look like "two white people", and the female figure definitely has an Asian look to her. They both look a trifle pan-ethnic, given the level of detail.The dude's hair? Well, you do have a point there.
We are way beyond "regulatory capture" now. It is a full-on hostile takeover.
Despite the reflex skepticism, this announcement makes perfect sense. The Space X "Mars rocket" ifs the BFR, which standards for (so they say) "Big Falcon Rocket", the first stage of which has 31 engines. Testing that these 31 engines all work together, and testing failure modes, is really important before trying an actual full scale launch.
I am not bothering to watch the YouTube video (really, that's your "reference"?) but the rocket equation derived from Newton's laws of motion were first formulated in 1813 by William Moore, again by William Leitch in 1861, but most famously by Konstantin Tsiolkovsky in the early 1890s, and published in a well-known work in 1903.
This is all really well known.
So, no. you are profoundly ignorant about this subject. Sorry.
If you actually read the WIkipedia section you reference you will see that this "common belief" refers to a common popular (i.e. laymen's) belief as exemplified by an editorial by the New York Times editorial staff. Journalists have never been known for their scientific literacy.
This a very famous journalistic science blunder.
This post does absolutely nothing for your credibility.
Meanwhile, it would be very fitting for Google and other deep-pocketed corporations with an interest in a global Internet and more balanced copyright to help Gutenberg finance its battle.
Google has lost all interest in the original mission to which it once referred of making knowledge available to the world (along with its watch-phrase "Don't be evil").
The near-death of the Google Books project is the poster child for this. Google actually won the lawsuit that the Authors Guild had waged against it for putting books, with limited search of snippets, on Google Books, and Google has a millions of out of copyright, out of print books - virtually inaccessible to the world - that it has already scanned and can be put on Google Books in the entirety to make them available to the world any time it likes. But it has dropped plans to do that. Books are still being added I read, but at a slow pace - not a priority. There are an estimated 25 million such inaccessible books out there that could be scanned and added, doubling the size of Google Books.
Google losing interest in supporting public access to published works shows up in lots of ways. It stopped updated the Google Books history page in 2007, its books blog has disappeared, its really useful NGram viewer stopped updating in 2008.
(And lately it was one of the five principle corporate sponsors of the CPAC wingnut festival.)
Only where there are stations. Believe it or not a high speed train running non-stop through your community does not raise land values.
And a lot of stations means no "high speed rail".
I agree fully with your remarks. There seems no prospect that fusion is going produce cost-competitive energy.
However I would like to see them build a practical (though very expensive) power plant. That will be an important step for developing fusion for where will really need it some day in deep space. Not until sometime next century at the earliest - but we can make progress in that direction now.
So... your bottle of anti-psychotics are talking to you? Maybe you need a different prescription.
Ah. So the real purpose is to advertise to others that you are rich when its dark and they can't see your car.
But, like the pharaoh and his attempt to beat back the tide, it'll all be for nought as the Marketeers will win.
The legend is about King Cnut (or Canute) who was King of Denmark, England and Norway (recorded 150 years after his death) and presents the opposite of what people believe. The point was that the King was showing his fawning courtiers that he was merely mortal and could not hold back the tide.
Oddly, no links or actual numbers in your assertions. Almost as if you were just passing on Uber hype. That is really strange.
A little Googling, even filtering for recently dated reports, repeatedly lists Uber drivers in the U.S. doubling from 2014 to 2015 (which represents flattening percentage rate of growth year over year from its founding). No actual reports of U.S. drivers since that time (but lots of people trying to extrapolate from it, as if this was an established law of nature). So, maybe it has not been doubling over the last three years.
Also half of all Uber drivers quit within 12 months. Why would they do that if the pay isn't crap (to turn around your argument)?
Lots of people here fixated on Australian tables (I've visited, they have nice tables).
No discussion of any of the actual findings though.
So far Dark Matter appears to interact only through the gravitational force, even with itself.
If, as this study suggests, "only cooling of the gas as a result of interactions between dark matter and baryons seems to explain the observed amplitude" and that interaction is anything other than a purely gravitational one, it will be the first evidence of Dark Matter interacting at all except through gravity. That could make this a really big deal. In about five years the first phase of the Square Kilometer Array should be able to greatly expand our ability to investigate this.
One beef with the summary is that there currently is no such thing as fossil fuels with carbon capture technology. There is NO industrial scale carbon capture or carbon sequestration technology available nor any reasonable prospect of such technology in the near future. So take that off the table as an option until such time as it becomes a real thing.
True, but since it is only needed to cover that last 20%, when we are already have 80% wind and solar, it is not needed now. We are currently at 15%, and at a reasonable 4.5% annual growth rate in production we will get to 80% in about 40 years. We can cut it to about 30 years at 6% a year, but in any case we are few decades off of needing this technology to be ready.
It is normal for a technology that is not yet needed not to be already deployed.
The cost of that last 20% is steeper on a percentage basis, but the aggregate cost is definitely not more (much less "much more") than the aggregate cost of the first 80%.
And part of the solution is not to demand that only solar and wind be used. Nuclear should still be in the mix (licenses are available for any capitalist who wants to build one) for example. There are a lot of options that could cover that last 20% (biofuels, carbon capture, nuclear as cited) and competition and innovation will push us toward the lowest cost way of doing it.
This is the study I have been looking/waiting for that gives a realistic assessment of what the future power grid for North America (and Eurasia) should look like.
The summary cites the two different options for dealing with the intermittent nature of wind and solar -- power storage (which is the go-to assumption everyone makes as the only option), and having a low loss national power grid to distribute power efficiently, but inevitably it only cites the cost of the more expensive of the two -- power storage. The report itself gives an estimate for the national grid option and it is only $410 billion dollars vs >$1 trillion for the storage option. Over a 40 year period this amounts to an investment of $10 billion a year. Currently about $70 billion is invested annually in electricity production and transmission, so this is in line with current and projected levels of investment.
It will be quite awhile before we have to really worry about going from 80% wind and solar to 100% - do we want to, is it worth the cost? In the mean time gas peaking plants can plug some of this gap. But nuclear energy at its current scale, about 20% of capacity, fits in very nicely. Currently licensed stations are looking at getting their licenses extended to 80 years, so they can cover this out to 2045 or so.
Of course there are straightforward fixes to this, well known in much of the world. A single electronic debit card for all forms of public transportation, with "recharge" opportunities everywhere (so that you can convert cash, bank balances, and credit lines into transportation balances). All this requires is to deploy readily available, thoroughly proven Internet based technology. If they can sell you a lottery ticket they can recharge your trip card.
I used the Opal card when visiting Sydney, Australia and it was a breeze. I got all around the city with no trouble, and not terrific expense.