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Submission Summary: 0 pending, 94 declined, 26 accepted (120 total, 21.67% accepted)

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Submission + - SPAM: Modified Gravity vies with Planet9 to explain Solar system structure- and fails.

RockDoctor writes: One of the serious contenders to the majority opinion Matter/ Dark Matter/ Dark Energy hypothesis for explaining the structure of the universe is the "MOdified Newtonian Dynamics" or MOND hypothesis in which the gravity field strength decreases not according to a 1/(radius^2) factor, but according to some other function of (radius), which would then explain the movements ("Dynamics") of galaxy-scale structures — the original evidence for postulating the existence of Dark Matter. This hypothesis dates back to 1983 — before the observations that prompt the Dark Energy hypothesis — and has been championed mainly (but not only) by physicist Mordehai Milgrom. While it is definitely not "mainstream" physics, it is certainly a respectable hypothesis.

One way to look for MOND effects is to look closely at the outer Solar system, where distances are larger than can be examined on Earth, but things are close enough for small effects to be measurable from Earth. And in a new paper published on Arxiv, people have done just that. The known "Extreme Trans-Neptunian Objects" ("ETNO"s — closest separation from Sol outside Neptune's orbit ; furthest separation 150 ~ 1500 AU) are closely clustered in direction — the evidence that Batygin, Brown, Sheppard and Trujillo have used in the last five years as evidence for a ninth planet in the Solar system. (No, Pluto is not a planet. Unless you want it to be about 10th or 11th in a 100+ planetary system.) It was possible that the MOND hypothesis might explain the orientation of the ETNOs, so the idea has been examined in detail (paper) — and found it less than 1% likely to explain the observations.

MOND remains an attractive type of hypothesis to explain the observational evidence of the universe's structure without postulating major changes in our understanding of physics. But again, it has failed at the test of new data types. Which still leaves physics with no viable alternative to the Matter / Dark Matter/ Dark Energy hypothesis.

Link to Original Source

Submission + - Aguments for the regualtion of SETI, and METI (Messaging ETI).

RockDoctor writes: John Gertz has been "an active leader in the field of SETI" for many years at the SETI Institute and Foundation for Investment in Research on SETI.

He makes some sober, and frankly dull points on the legal/ policy front ( though the prospect of "the Aliens" having First Contact with ISIS or Kim Jong Un is ... unsettling). However, he also discusses more interesting options.

This author has argued elsewhere that the artificial signal that we first detect may more likely derive from within our own Solar System than from a source outside of it.

Hows that?

Given the widespread of times and possible locations of the origin of life, Gertz thinks that it is plausible that an ETI seeded the galaxy with passive probes that would wait (in shelter) for development of (technological) life within their area, and then initiate communications. If, for our putative ETs, interstellar travel proved impossible for some reason, they might at least have contact with later intelligences by scattering probes around the galaxy which every so-often would "wake up", sample their area for interesting signals, and go back to sleep again for a few generations.

All very "Monolith" (Arthur C. Clarke SF story, later made into several films). But what if a probe hibernating around Sedna were to wake up to I love Lucy? It's response (indeed, it's body) could on the way today, and arrive next week at a DPRK listening post — who choose to reply in secret. To what effect? What could the nuclear power of DPRK do with an alien version of Encyclopedia Galactica 54321 — in comparison to our Encyclopedia 2000?

Gertz raises some probably important policy points, but some really fascinating ideas.

Submission + - Fast Radio Bursts - the astronomical signal - may be from extraterestrial source (arxiv.org)

RockDoctor writes: In an exercise of "try all sorts of ideas", some Harvard (USA) astronomers examine coincidences between "fast radio bursts" (the several uhh "enigmatic" uhh, fast bursts of radio emission detected over the last few years) and discover that the plausible sizes of the sources of the signals and some of their other characteristics are not inconsistent with them being sourced from "a large rocky planet."

They continue to examine the far-fetched idea with the tools of science. The extemely high brightness temperature (change of intensity with radiation frequency) of ~10^37 K has suggested a coherent radiation source, and tihs idea is developed into considering them as the overflows of light sails powered by a radiation source at the source planet, as has been proposed for investigating the planet around Proxima Centauri.

In an acknowledgement of the Popplerian definition of a scientific hypothesis, they are explicit in discussing "implications and predictions in Section 3", so their ideas can be probed by reality. So even if their idea proves wrong, it will remain a valid contribution to the literature. As the authors finish, "Although the possibility that FRBs are produced by extragalactic civilizations is more speculative than an astrophysical origin, quantifying the requirements necessary for an artificial origin serves, at the very least, the important purpose of enabling astronomers to rule it out with future data"

Submission + - A nemesis for Nemesis? (arxiv.org)

RockDoctor writes: That's "Nemesis", the hypothesised companion star to the Sun, proposed as a cause of periodic (~24 million years) mass extinctions. This was proposed as a larger object, further out than the recently much debated "Planet Nine" of Trujillo, Sheppard, Brown & Batygin), while the geological evidence for periodic mass extinctions has teetered on the edge of statistical (in-)significance.

In 2010, additional analysis of fossil data improved the statistical basis for the perceived periodicity of extinction, but their simultaneous analysis of the orbital mechanics convincingly made "Nemesis" an even less likely explanation.

New data from a different source is clarifying the matter. The Earth's magnetic field reverses irregularly but frequently (we may have been in the early part of a reversal for a millennium or two), and leaves a record in the rocks. In the last few years, this accuracy of this record has been improved and the analysis now goes back to 375 million years (Myr) — about the time that our ancestors were crawling out of the seas and onto the land — and more tentatively to 600 Myr ago. This record also displays periodicity in the rate of reversals. The strongest signals recovered are at 25.5 and 29.4 Myr, compatible with previous results from extinction rates.

No known process (unless the hivemind of Slashdot knows better?) from outside the Earth can influence the motions in the Earth's core that generates the Earth's magnetic field, but the magnetic field can change the level of (cosmic) radiation at the Earth's surface and potentially influence extinction rates that way. Though the increase in radiation at the surface is admittedly "slight".

This is not likely to be a final solution to the question of periodic extinctions, but does look to be a significant step forward.

Submission + - Obama comutes sentence on Chelsea Manning

RockDoctor writes: The BBC are reporting (as of 10 minutes ago) that outgoing US president Barack Obama has commuted the 35 year sentence passed on Chelsea Manning for espionage in the leaking of (amongst other things) diplomatic cables which showed the US diplomacy service in a less than favourable light.

[Manning] will be freed on 17 May instead of her scheduled 2045 release.

Unless of course, Trump counters with a death penalty. 'Cos, you know, he has small hands.

Submission + - SPAM: A COLD gas giant is detected - probably a Solar-like system.

RockDoctor writes: For 8 years now we've been used to a steady stream of discoveries of planets orbiting stars from the Kepler satellite, and a smaller stream of discoveries from high precision "radial velocity" surveys of selected stars. But both of these techniques are strongly biased to detecting large planets in close orbits around their star — which is decidedly not the configuration of the Solar System.

Another technique for detecting distant dark objects also returns a small number of planet detections. "Microlensing" surveys look for the effect of objects passing between Earth (well, telescope) and a distant star, when the intervening object effectively acts as a lens to focus light from the distant star towards the telescope for the period of the alignment. Individual events are unpredictable and rare — literally million-to-one events. So, if you look at a millions of stars at once (easily done by looking at the dense star clouds in the centre of our galaxy, or in the satellite galaxies of the Magellanic Clouds), and record the brightness of those millions of stars thousands of times each through years of observation (just the recording is non-trivial — you're looking at billions of data points), making sure that you assign the correct brightness datum to the correct star's record, then eventually you will discover sporadic brightening events. And some of those have the simple shape of flares on the star, but some have the complex shape of a transit of an object amplifying the light of the background star during it's temporary alignment with the telescope.

It sounds improbable, but these lensing events have been found repeatedly in the last few decades. And as data acquisition and database processing has improved, more objects are being seen, and more information extracted from those observations.

A paper this week on Arxiv (accepted for publication in MNRAS) anounces the recovery of the transit of a star and planet system which sounds much more like the Solar System then most of the thousands of candidates from Kepler. From the complex variation of the brightness during the transit, the star is most likely to be about 2200 parsecs (7200 light years) from Earth, has a mass of 0.62 times the mass of the Sun ; the planet is between 2 and 4 times the mass of Jupiter, and their separation between 3 an 5 AU (Jupiter is 5.2 AU from the Sun). Compared to the typical Kepler discovery, with a "hot Jupiter" orbiting at a small fraction of an AU from their star, this is a far more Solar-like system than most.

The question of "how many Earth-like planets are in the galaxy?" remains open, but steadily it is moving from the realms of unconstrained science fiction to a matter of statistics.

Follow-up observations are planned to search for the lensing star (and attendant planet) as it moves out from the glare of the background star. By that time there may be a more memorable name than "OGLE-2014-BLG-0676Lb"

Submission + - A physical model for (some of) Tabby's Star's light dips. 2

RockDoctor writes: A fresh paper on Arxiv describes a model proposed to explain at least some of the light dips in "Tabby's Star" (Kepler Input Catalogue KIC 8462852). When the irregular light received from this star was recognised in 2015, nobody could come up with a credible explanation for the irregularity of the star's light dips, or their depth. Further studies suggest sustained dimming over the photographic observation epoch, further deepening the puzzle. This new paper proposes a model of a jet of material which leaves the star's surface, then casts off a plume described as "smoke plume" which is swept around in the stars orbit. The opaque jet and the less-opaque "smoke plume" then intersect with the light travelling towards us to generate an asymmetric dip in the star's light curve, as observed in the past.

Which is an interesting model. The big peculiarity is that the "smoke plume" orientation with respect to the material jet implies that the outer parts of this star's envelope is rotating faster than the inner part where the jet originates. Which would raise almost as many questions as the original discovery.

Definitely, this is a very peculiar system.

(PDF here ; NB, the paper does not appear to have been submitted to a journal, or peer-reviewed.)

Submission + - Cards Against Humanity are in a hole! (holidayhole.com) 1

RockDoctor writes: Well-known enemies of Political Correctness "Cards Against Humanity" have moved on from sending people un-funny phrases on bits of card (which users then combine into hilarious, offfnsive, or hilariously offensive combinations) to their annual festive "thing". Having previously raised prices, delivered Lance Armstrong's missing testicle, and sent people bullshit, this year's comment on "Black Friday" is to dig a hole with user's contributions. And that's it. No more. Nothing will happen apart from an innocent piece of land will become a hole. An expensive hole. A hole into which users have willingly poured money instead of doing something useless.
So vote with your credit cards and get that hole dug. There are (at the time of this submission) 29 hours and 52 minutes to pour your money on top of the $30,400 already poured into this hole in the ground. No matter how much you pour in, you'll never get the hole to over flow, but don't let that stop you trying! (29h 43 minutes now, and $32,000.)

Submission + - The iron fist pokes out through the velet glove. 1

RockDoctor writes: Google are (allegedly) shutting down the Google Accounts of people indulging in a sales-tax [trick/ scam/ workaround — IANAmerican, so I'm not sure on the legal status of this], blocking them from access to photos, emails, contacts and the other detritus of a digital life. The Guardian adds : "Google has suspended the accounts of hundreds of people who took advantage of a loophole in US sales tax to make a small profit on Pixel phones.
The Google customers had all bought the phones from the company’s Project Fi mobile carrier, and had them shipped directly to a reseller in New Hampshire, a US state with no sales tax. In return, the reseller split the profit with the customers."

"One user reported that an account that hadn’t been used to purchase a Pixel was suspended, apparently because it was listed as a back-up address for an account that had."

People might ask, in a hurt tone of voice, "why are you doing this to me?" To which the obvious answer is "because we can, and you agreed to these (link to 3000 pages of text) terms and conditions, including our ability to do this."

Totally expected behaviour. The only question has been 'When?', never 'If?'

Submission + - All about life around an M-class star

RockDoctor writes: Arxiv has a review article on "The Habitability of Planets Orbiting M-dwarf Stars" (PDF). Although Star Trek had a minor smattering of "M-class planets" — a designation that tells one nothing of substance, "M-class star" is a much more meaningful designation of colour, with two size classes, the dwarfs and the red giants. M-class ("red") giants are not prospective for life — it's a short duration of the life of any star that gets into that state (most won't) and it ends badly for anything not made of tungsten carbide. M-class dwarfs, on the other hand "are our galaxy’s silent majority: they constitute 70% of the stars in the Milky Way and 40% of its stellar mass budget, yet not a single M dwarf is visible to the naked eye. They span nearly an order of magnitude in mass and two orders of magnitude in luminosity. [...] As a spectral class, M dwarfs span a larger range in mass than the next three spectral classes (F,G & K) combined." But probably the most important reason for paying attention to them is their persistence — an M-dwarf of 1/10 the mass of the Sun will burn for around 1000 times the time that the Sun does. No M-dwarf has ever turned into a red giant — there hasn't been enough time.

Therefore, if humanity ever meets an alien species, the odds of them coming from an M-dwarf are already high. If humanity ever meets an alien species that has been around a billion years longer than us and has technology we can't even dream of, then the odds of it coming from an M-dwarf are overwhelmingly high. Clearly, understanding these stars, and the influences of these stars range of properties on their planets and possible inhabitants (including our distant descendants) is a good idea. And this review article will keep you up to date for your next term paper. Or for keeping your SF magnum opus somewhere with a passing acquaintance with reality.

Submission + - Samsung are investigating the effects of the '7' fiasco on their brand.

RockDoctor writes: I routinely fill out for-pay surveys for a commercial survey company for an earning rate somewhat better than minimum wage.

I had one just now for Samsung, inestigating the effect on their brand's perception of the Note 7 battery fiasco. While I'm not particularly worried — the difficulties of high energy density devices have been known since the Chinese started putting fireworks in their robes and getting burned — it does show that Samsung are worried about the consequences. Contrary to what some of the more hysterical Apple fan-bois say.

Personally, I don't give a shit if $DEVICE$ is a bit thicker. My current $DEVICE$ (an S5) resides in a fold-over wallet which effectively doubles it's thickness, and to no-one's astonishment, it still fits in my pocket, AND it hasn't yet borked it's screen when I've dropped it.

Submission + - It doesn't look too good for Tatooine.

RockDoctor writes: Everyone who has paid even the most cursory of attention to the Star Wars films (I've seen at least two of them. Out of however many.) knows that the planet Tatooine orbits two stars in close binary orbits. But everyone who has paid even the most cursory of attention to astrophysics knows that the evolution of the stars is likely to have ... consequences ... for any planets in orbit around the system's centre of mass.

A paper published yesterday on Arxiv studies the known planets in Tatooine-like systems (PDF). The Kepler telescope has confirmed a number of planets around close binary star systems. So astrophysicists have studied the evolution of these systems.

It doesn't look good for Tatooine-like planets. Of the nine systems studied, five experienced "common-envelope stages" where gas is transferred from the lighter of the two stars to the heavier (which changes the evolutionary trajectory of both stars). This is not good — cataclysmic novae and X-ray outbursts are common outcomes. On the other hand, "two systems trigger a double-degenerate supernova explosion" — which doesn't sound like it'll be good for the sunburn either. Those planets which don't suffer "RUD", don't do much better, as the "common-envelope stage" and the resulting gas drag and close-approaches can lead to 10-fold increases in both orbital diameter and eccentricity. In as little as one planetary orbit. Double-plus ungood.

All in all, Tatooine-like planets would probably not be a place to put a long-term centre of government. So actually, Lucas wasn't far wrong.

Submission + - Crib-sheet for Gravitational Wave essays. (arxiv.org)

RockDoctor writes: Those of you studying — be it astronomy, physics, or crochet — will probably have already faced the need to write a few thousand words and equations on the subject of gravitational waves (GW). So, if you hold the "popular science" opinion that Einstein predicted the existence of GW in 1916, then you might just want to read this review essay prepared by Nobel laureate George Smoot and two others. For the first 50 words of your essay, Smoot et al. trace the idea of GW back to "an article written by Henri Poincare entitled “Sur la dynamique d’ l’électron.” This work summarized his theory of relativity. The work proposed that gravity was transmitted through a wave that Poincaré called a gravitational wave (onde gravifique)" in Comptes Rendus. (OK, this journal title is in French, but not all of the articles are, this century. This article is though, so you'd better sharpen up your passe passif. The paper is available via the Bibliotheque National Francais here. And here is the necessary rant about the ridiculousness of not being able to type a C-cedilla due to Slashdot's inability to handle non-ASCII characters.).

Another 30 pages (including references) describes the "theoretical and experimental blunders, efforts towards their detection, and finally the subsequent successful discovery," including the inevitable bets and the occasional millionaire chucking a moderate amount of funding at this ridiculously wild field of study.

Submission + - How will we know a vehicle model is "driverless" (example.com)

RockDoctor writes: Some people differ, but having gone through dozens of (simulated) aircraft crashes as part of safety training for work, I hugely prefer to face backwards when travelling. Plane (no choice) train (choice) or automobile (rarely a choice), I prefer to be in a seat that will absorb my momentum from the start of an impact.
The "driverless car" will not be here until all people in the front row of the device face against the direction of travel. Anything less is a partial solution, waiting for a human to take over in a complex situation.
My wife can't travel facing backwards. So I take the risk of being killed by her flying body after I survive the crash. Joy, not.
People will learn to live with it.

Comments?

Submission + - Continuing progress on "In Situ Resource Utilization" for space exploration. (arxiv.org) 2

RockDoctor writes: Many Slashdot readers will have heard of Robert Zubrin with his plans for launching self-contained rocket fuel plants to Mars to convert 1kg of hydrogen (supplied from Earth) to 18kg of oxygen/ methane to be used as rocket fuel to return explorers to Earth. This is an example of Utilizing (using) In Situ (already there) Resources (Mars' CO2 atmosphere) to reduce launch costs (masses) from Earth to achieve desired aims in space exploration at more affordable costs.

In 2013, the Journal of Aerospace Engineering ran a special volume on "In Situ Resource Utilization" with 20 papers on the subject. (These are paywalled, unless you know of tools like Sci-Hub to read the work paid for by your taxes.)

Yesterday, one of the editors of that special volume, Philip Metzger (a NASA planetary scientist specialising in the properties of Lunar soils) released a paper on Arxiv expanding on his contribution to that 2013 volume and detailing a roadmap for humanity to take gain control of the Solar System in order to solve problems on Earth. In the 2013 paper, Dr Metzger asserted (with working) that

bootstrapping can be achieved with as little as 12 t landed on the Moon during a period of about 20 years. [ I know it's Slashdot but RTFAFFS ! ...] The industry grows exponentially because of the free real estate, energy, and material resources of space. The mass of industrial assets at the end of bootstrapping will be 156 t with 60 humanoid robots or as high as 40,000 t. [...] Within another few decades with no further investment, it can have millions of times the industrial capacity of the United States. Modeling over wide parameter ranges indicates this is reasonable, but further analysis is needed.

The 2016 Arxiv paper produces some of the results of that further analysis, concentrating in particular on the need to develop a "water economy [..] to manufacture rocket propellant" from in situ resources on the Moon and later the asteroids.

The 2013 paper's abstract ends with one of the milder understatements in history.

"This industry promises to revolutionize the human condition."

Without doubt, Slashdot will contribute much heat and little light from typing hordes who haven't read either paper to dilute their ignorance, but analyses like this are not, as frequently described, the work of "space nutters" but realistic possibilities. Realistic until the author sees the fatal stumbling block to all such dreams :

"It will require a sustained commitment of several decades to complete."

— a level of dedication that humans have not shown themselves capable of for centuries, even for their highest achievement to date, war.

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