Researchers have identified 100 mysteriously disappeared stars in the night sky
sciencealert.com
sciencealert.com
But it is still an interesting story and a topic worth exploring, even if subsequent research concludes the team has found 100 smudges on glass.
> operator error
would effect the entire image. If it were damage to the film/sensor, scratches etc, it wouldn't look like a star point source with a star like point spread function.
> hardware error, noise
Digital sensors do add noise to an image, but it doesn't occur as bright point sources concentrated in a small area. noise can be removed through statistical analysis, dark frame subtraction, lucky imaging, etc. Dust on the lenses or mirrors aren't in the focal plane and don't resolve to points. Dust on film or sensors would block light, not produce it. Many exposures all over the sky quickly characterize the on sensor defects and other instrument specific information that can be removed from the data.
> anomalous near-earth objects
these are long exposures, if they are anomalous objects, they would have to have very slow apparent motion against the stellar background. satellites and planes would leave trails. balloons would drift with the wind. what would stay basically static through the entire long-exposure against the celestial sphere?
I appreciate your skepticism, I'm just taking the other side of the argument. Thoughts?
This study is based on the catalogue of 600 million objects, 60 times more than 10 million times:
"In this latest study they compared 600 million objects in the USNO catalogue with a collection put together by the University of Hawaii's Pan-STARR system."
"In an earlier study Villarroel and her team compared the positions of some 10 million objects"
Emphasis mine.
Actual birth records show that different numbers of people are born on different days. In this case, it can be shown that the number of people required to reach the 50% threshold is 23 or fewer.[1] For example, if half the people were born on one day and the other half on another day, then any two people would have a 50% chance of sharing a birthday.
It may well seem surprising that a group of just 23 individuals is required to reach a probability of 50% that at least two individuals in the group have the same birthday: this result is perhaps made more plausible by considering that the comparisons of birthday will actually be made between every possible pair of individuals = 23 × 22/2 = 253 comparisons, which is well over half the number of days in a year (183 at most), as opposed to fixing on one individual and comparing his or her birthday to everyone else's.
..they notice that "overhead, without any fuss, the stars were going out."
In it, an Astronomer spots a star that disappears. This star is 1,500 light years away. He travels to another star system (Humanity is a multi-system species) and observes the star again, at just the right moment to see the light from its disappearance. It disappears within a couple of seconds, as does a nearby star. But its infrared output is undimmed.
This kicks off an epic, and I really do mean epic, space opera. Peter F Hamilton is really great at such stories, and I love this pair of books so much that I've read them about a dozen times each.
Highly recommended!
The Commonwealth Saga (mentioned by the parent) is followed by The Void Trilogy and then The Chronicle of the Fallers, all set in the same Commonwealth universe. It’s some of the most evocative writing I’ve ever heard the pleasure to read, and the stories told are massive in scale but without seeming lacking as a result.
My e-reader says that my most recent read-through was my 9th, so add that to a number done with physical books and it should give some idea of how good I consider these books!
And my favorite sci-fi authors are Heinlein and Lem, so calibrate accordingly.
[0] https://en.m.wikipedia.org/wiki/Peter_F._Hamilton_bibliograp...
Misspent Youth apparently is set 300 years before the 2 other books, and establishes the setting. The author does a great job of creating the universe in Pandora's Star so I don't think you need to read Misspent Youth.
I'd be interested to hear if you enjoyed the books. If you want, email me at the address in my profile.
"The Negation of the Negation of the Negation" ( http://www.bigecho.org/the-negation-of-the-negation-of-the-n... ).
"We show that these objects are redder and have larger proper motions than typical USNO objects." -- Interesting, not sure what that'd imply.
"A particular focus is given to USNO objects that have several detections before vanishing" -- implies that these at least some of these objects are not just detector glitches or scratches or similar, although "Visual checks confirm that indeed the most interesting cases, about 100, are mostly one-time detections in the red band."
"In a separate paper by K. Pelckmans et al. (2019, in preparation). we propose a new tool for handling a large number of images using methods of machine learning." (since people were talking about ML in astronomy)
So that could be fusion torch flashes. Or maybe weapons.
I wonder if they have spectra for any of these suspects.
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* Removed ~100 stars to fix bug #9533465222. If your star was affected, please reach out to customer support.
“The star vanished from the centre of the telescope’s image in less time than a single human heartbeat. There was no mistake, Dudley Bose was looking right at it when it happened. He blinked in surprise, drawing back from the eyepiece. “That’s not right,” he muttered.
He shivered slightly in reaction to the cold air around him, slapping gloved hands against his arms. His wife, Wendy, had insisted he wrap up well against the night, and he’d dutifully left the house in a thick woollen coat and sturdy hiking trousers. But as always when the sun fell below Gralmond’s horizon, any warmth contained in the planet’s thinner-than-average atmosphere evaporated away almost immediately. With the telescope housing open to the elements at two o’clock in the morning, the temperature had dropped enough to turn his every breath into a streamer of grey mist.
Dudley shook the fatigue from his head, and leaned back in to the eyepiece. The star field pattern was the same, there had been no slippage in the telescope’s alignment, but Dyson Alpha was still missing. “It couldn’t be that fast,” he said.
He’d been observing the Dyson Pair for fourteen months now, searching for the first clues of the envelopment which would so dramatically change the emission spectrum. So far there had been no change to the tiny yellow speck of light one thousand two hundred and forty light-years away from Gralmond which was Dyson Alpha.
He’d known there would be a change; it was the astronomy department at Oxford University back on Earth that had first noticed the anomaly during a routine sky scan back in 2170, two hundred and ten years ago. Since the previous scan twenty years earlier, two stars, a K-type and an M-type three light-years apart, had changed their emission spectrum completely to non-visible infra red. For a few brief months the discovery had caused some excited debate among the remnants of the astronomy fraternity about how they could decay into red giants so quickly, and the extraordinary coincidence of two stellar neighbours doing it simultaneously. Then a newly settled planet fifty light-years farther out from Earth reported that the pair were still visible in their original spectrum. Working back across the distance, checking the spectrum at various distances from Earth allowed astronomers to work out that the change to both stars had actually taken place over a period of approximately seven or eight years and was simultaneous. Given that speed, the nature of the change ceased to become a question of astronomy; stars of that nature took a great deal longer to transform themselves into red giants."
-- Peter F. Hamilton. Pandora's Star
I'm reminded of an old Bugs Bunny cartoon: Detective: "Okaaaay, start at the beginning." Bugs: "In the beginning, the Earth was without form and void ..." Detective: "You can skip ahead a bit, thanks ..."
Brilliant portrayal of power and intrigue though.
I personally was engaged for the entirety of both books, but found the trilogy set in the same universe (The void trilogy) dragged a bit in the third book.
I highly highly recommend them.
This is a candidate for the Great Filter: interstellar civilizations that come into contact destroy one another.
[0] https://en.m.wikipedia.org/wiki/The_Dark_Forest
[1] https://bigthink.com/scotty-hendricks/the-dark-forest-theory...
Dropping a black hole, even a smallish one, into a star would seem to eliminate the central pressure needed to sustain fusion, and turn it off pretty suddenly, by astronomical timescales.
Although, it doesn't really make sense. Like a puncture in the wall of a pressure vessel, the pressure at the event horizon would be zero. It is hard to see how an accretion disc could form in pure plasma at such density. The fluid dynamics of plasma under such conditions is entirely intractable, so it is also hard to believe in any claimed solution.
But temporarily multiplying the output of a star might work just as well to eliminate a pesky alien infestation.
If I understood correctly, and that is conventional practice in calculations about black hole accretion discs, there is a great deal of nonsense published on the topic.
The expanse seems “lighter” or less hard. The last book, deaths end i found to be particularly “hard sci-fi”.
Say you are a few million year old civilization and you detect radio from a civilization 100k light years away takes 500k years for you fleeting arrive. You are still millions of years ahead in technology. If you are a stagnant civilization you probably stay home cause the other side would overtake you, but then again that motivation to get to them as early as possible. In any event presumably as your fleet get closer you would have a better idea of the technology difference and can just do a U turn
The longer they go without contact, the wider their reach, and the greater their odds of contact.
We might suppose that the technology necessary to obliterate another civilization is arrived at early, and is hard to counter despite long subsequent development. Alternatively, civilizations that succeed in suppressing weaker ones eventually meet their match.
Compared to a Dyson sphere - which only requires a tiny, tiny, tiny fraction of the energy absorbed to build and launch the orbiting platforms that make-up the sphere.
You can "ignite" a gas-giant by maneuvering a black-hole into position inside the gas-giant, but (as far as we know) there are far more gas-giants than there are black-holes, and the distances involved are tremendous (nearest black hole: 3,000ly, nearest gas-giant: 6 to 9e-5 light-years). It just doesn't strike me as feasible or even worthwhile even if it was feasible.
Maybe as the heat-death of the universe approaches, the last band of remaining humans (don't ask) try to ignite the gas-giants to keep the lights on?
We don't build bonfires in our cars, as used to be done in steam locomotives; we oxidize carbon differently, and generate a pressure differential by entirely different means. Why should advanced aliens do things the clumsy way?
Anyway there isn't enough material in a solar system to build one. If you can get elsewhere to gather the stuff, why bother to bring it back?
You'd need trillions of them per galaxy, but that's well within the capability of a type III civ.
It reminds me of the extra solar object detected a couple years ago that buzzed the Earth and then mysteriously ACCELERATED out of the system.
So assuming we were just detected and assuming there's a berserker in the system already (likely in an outer orbit) that would imply we have only a couple decades left.
Just to give some background, I watched that movie not realizing what it was based off of, just knowing it was a chinese sci-fi. And I remember being amazed at how big the ideas were and thinking China must have a culture of exceptional sci-fi writers. Afterwards I did some research and realized who it was.
Cixin Liu is the author and he's so good at big ideas. I can't recommend his stuff enough.
edit:
link
One of the things it did really well was the idea that it takes everyone pulling in the same direction to be effective.
I realize there exist people who like sci-fi and think The Three Body Problem is good, but... I can’t understand what they see in it. The last 50 pages or so was at least an ok short story...
The last 50 pages of the third volume were not worth the paper.
Will check out the wandering earth. Thanks.
Civilizations would get to a level of science where they find out and even if they could reach us before the reset, there'd be no point. Like when you're playing a video game and you get "server shutdown in 30 minutes", you log off right away or mess around until it happens.
The Great Filter is only limited by our imagination and doesn't even have to involve us at all.
There's a planet that's trying to achieve peace. They're in the middle of a cold war, looking rather like earth, half hour ends with the failure of talks and a nuclear war. Camera pulls back to two alien teens playing an intergalactic arcade game, now showing "game over".
Perhaps the one playing the sim got bored and started star killing their own solar systems.
I imagine there are a lot of possible ways a line of site occlusion could cause a dim star to appear as not existing at all, and as another commenter mentions, maybe the original measurement was some sort of amplification in the first place.
Space is damn cool.
Lensing could also move the (perceived) location of a star.
Im not sure how much lensing happens within our own galaxy.
What about the possibility that the inclusion of those stars in those 1950's star catalogs was a result of human error, instrument error, or scientific fraud?
Looking at the brightness of the source that went missing, it is hard to suggest instrumental error - much fainter stars remain detectable in both epochs.
And fraud, really? Who would bother to fake stars in catalogs and plates in the 1950s, and why?
I think if there is an instrumental error it would more plausibly be the opposite. That the bright stars are artifacts in the images.
Stellar cartographers aren't selling unique branded star catalogs, so there is no reason to complain if someone has copied your data. The incentives are completely different.
Video of ten years worth here: https://www.facebook.com/watch/?v=10160104518220167
> It could also be a dull star we assumed was farther away and has just moved too far to be noticed.
https://www.greaterwrong.com/posts/5wMcKNAwB6X4mp9og/that-al...
"We visually examine the images for a subset of about 24,000 candidates, superseding the 2016 study with a sample ten times larger. We find about ∼100 point sources visible in only one epoch in the red band of the USNO which may be of interest in searches for strong M dwarf flares, high-redshift supernovae or other catagories of unidentified red transients.
Comments: SETI meets time domain astronomy."
"The Vanishing and Appearing Sources during a Century of Observations Project. I. USNO Objects Missing in Modern Sky Surveys and Follow-up Observations of a "Missing Star"" Beatriz Villarroel et al 2019 December 12, The Astronomical Journal, Volume 159, Number 1
However, that seems to have been ruled out in the Astronomical Journal article:
"Given the exposure time of 45 minutes of the POSS-I E red image, if our object were an asteroid that quickly moved out of the field, it would have left a stripe (and not be point-like)." (Page 5)
"The exposure time for the red image is about 50 minutes. If the object were an asteroid and was quickly moving through the field of the red image in a few minutes, then it would be elongated on the plate. However, this object is point-like. In addition, the candidate is anomalously red and not seen in the blue band, which further decreases the likelihood that it is an asteroid." (Page 13)
There are patches in the sky.
"Hmm, we've observed something weird. What could be some reasonable explanations? We'll dedicate 3 to 4 sentences on those then spend the rest of the article talking about Dyson Spheres and extraterrestrial star ships."
From the abstract:
The implications of finding such objects extend from traditional astrophysics fields to the more exotic searches for evidence of technologically advanced civilizations
https://iopscience.iop.org/article/10.3847/1538-3881/ab570f#...
https://www.tillett.info/2016/08/03/carnot-efficient-dyson-s...
We’d expect to see Dyson swarms’ heat signatures because of the laws of thermodynamics. If super-advanced aliens can avoid or circumvent thermodynamics, all bets are off.
I’m not a trained physicist, so I’m not 100% certain about this, however the phrase “there is no stealth in space” seems to come up a lot in the stuff I read, and that specifically excludes directing heat away in specific directions.
Point that V into deep intergalactic space and buy yourself a few hundred million years.
A Dyson Sphere has to radiate.
As ben_w said and I fully agree with, if you're going to hypothesize a level of technology that can somehow get around that, that's fine and all, but if you're going to invoke magic, you really haven't got any justification for stopping at such a particular place. They could be aliens that have figured out how to shunt energy into the 5th Dimension instead of radiating it out into our universe... but they might also just be elves casting magic spells. Intuitively, it may seem like there's a lot of difference between those two things, but... there really isn't so much.
https://arxiv.org/search/?query=astronomy+machine+learning&s...
Plenty of ML work being applied to astronomy. Much of the code is open source too so you can dive right in and contribute.
Here's a recent survey you might start with: https://arxiv.org/pdf/1912.02934.pdf
Anyone else have any thoughts? Also where could these images be accessed?
[1]: https://en.wikipedia.org/wiki/Journey%27s_End_(Doctor_Who)
Are stars also appearing?
What is not clear to me is whether one can find these missing stars on other plates taken at a later time. If so, then this lends credence to some sort of stellar phenomenon. The paper rules out asteroids due to the long exposure times of the images, which would have turned any objects moving in our solar system into a smear rather than a point source.
Perhaps also different wavelength star sources too? Or are they doing the observations across the whole spectrum (that's probably common nowadays?).
That short list was visually inspected, excluding around 18,000 images that were messed up by flaws or artefacts. Lastly, the team removed images where the missing star was towards the edge of the field, just to reduce risk of any false positives.
One final sweep using yet another method for comparisons removed other possible flaws in data collection, or unclear results. That left 100 dark shadows where a star once shone.
[0] https://www.livescience.com/64033-shape-of-a-wormhole.html
I would assume so. It probably takes a lot of energy to rip open a hole in spacetime, much less keep it open, and the only things we know of that can do anything like that are black holes. But unlike black holes, a wormhole wouldn't have an event horizon (otherwise you wouldn't be able to go in and come back out) so all of that energy can't be captured, it has to radiate somehow (as it does even with black holes as Hawking radiation.)
Also, the endpoints may have their own accretion disks or there may be red or blue-shift effects that may be detectable, due to the relativistic effects of the endpoints and dark energy expansion.
Basically, this seems like a "stealth in space" problem, and the consensus is that there "ain't no stealth in space[0,1]."
Space is very, very empty and very, very uniform in temperature, as well as being an insulator because it's a vacuum... anything warmer than cold space itself is going to be hot enough to be noticed. The second site linked there mentions that it would be possible to detect a Space Shuttle using its thrusters from across the solar system with current technology. A wormhole big enough to see an entire star through should definitely be giving off something.
>Can energy be expelled in ways not visible to these types of devices possibly?
Not without using more energy and generating more heat. You can't escape the laws of thermodynamics.
>I’m curious if they should try imaging the stars in another sort of way than the past and present catalogues have done in order to possibly capture this any sort of anomalies that we may not currently be aware of.
I'm sure they've put a lot more effort into considering reasonable alternatives than you or I have. But AFAIK, many models of wormholes exist in various physics models, and require exotic matter with negative mass (also only known to exist in theory) to allow any sort of traversal at all, so it's not surprising that astronomers haven't tried ruling them out since at the moment we don't even know if they exist or, if they do, what properties they have.
[0]http://www.projectrho.com/public_html/rocket/spacewardetect....
[1]https://worldbuilding.stackexchange.com/questions/23313/stea...
It seems like now might be the perfect time, for the price of a single space telescope, to build an exa-scale computer capable of simulating every extreme astrophysical event.
Technosignature "clues", and all probable causes could be instantly classified. It's now also possible to add gravity waves and neutrinos to the simulation ;)
This axiom works in the fictional universe of Sherlock Holmes, where it's guaranteed that the protagonist will know all of the variables with perfect unbiased clarity and can, therefore, eliminate all unnecessary possibilities and solve the case.
But in the real universe, one often cannot "eliminate the impossible," because one cannot always know everything that is possible, or where ones assumptions are wrong.
>It seems like now might be the perfect time, for the price of a single space telescope, to build an exa-scale computer capable of simulating every extreme astrophysical event.
This is a good example of what I mean. We don't know what the set of all extreme astrophysical events contains, or what their nature is (ex: dark matter and dark energy) and we're constantly discovering new events and phenomena. If we could perfectly simulate the universe in this manner, we wouldn't need to.
And this is why, despite many fields of science already spending far more than 'the price of a single space telescope' to simulate everything from the Big Bang to biology and neurons to particle collisions, "instant classification of everything" isn't possible.
That's just not a thing that computers can do outside of science fiction.
Perhaps not worthy of exa-scale computing resource allocation. When it could be put to better use in say, nuclear fusion instability prediction. And with the qualifier "possible" conditioned on "known astrophysics by humans in the early 21st Century". But still an interesting tool for likelihood candidate detection.
And it still seems constrained to me at least (not a professional astronomer) by the scale of astrophysical phenomena which would be detectable here across the vast expanse of space. It could be an infinite set, certainly.
But so far we have cataloged only a handful of significant sources of, in the case of gravitational wave interferometry, bursts: black holes, quasars, pulsars, neutron stars...