Pure speculation, isn't the most interesting time period in the signal the transition from signal to no-signal (and back again)? How high is the resolution of the sensors? Is it possible that some frequencies are blocked fractionally earlier than others? At a fine enough temporal resolution, there might be more clues regarding the source.
Good question. For many FRBs there is access to the original antenna time streams (which are essentially voltages samples at 800 MHz), so superficially that might give you 1.25ns resolution. However, the intrinsic width of the pulses seem to be more like ~1ms. That tells you something about the emission source, giving you a rough upper bound on it's size of c * 1ms ~ 300km.
However, lots of interesting plasma physics effect occur between us and the FRB. The dominant thing that happens is that low frequencies arrive later than high frequencies (as they travel slow in a plasma). This causes the FRB to be smeared over many seconds rather than a millisecond. There's also multi path interference effects and an whole bunch of other stuff that happens. So actual the temporal structure of the burst tells you much more about the intervening medium than it does about the source.
A broader question that puzzles me, not specific to this phenomenon. Pulse length is often used to bound the size of a source in space (it cannot be smaller than light takes to traverse the object). But it’s possible that two phenomena can be correlated without being close, if there is a delayed action (akin to setting two alarm clocks and separating them in space). How can we confidently use this as evidence of size?
I guess the assumption is that the phenomenon starts at a point, spreads across the object sized l at c, and lasts for only a period of time t at any location. Therefore the pulse ends after l/c + t = T. By measuring T you can put an upper bound on l.
Example of this inference, from the Wikipedia on Fast Radio Bursts (but I have seen in many contexts):
> The sources are thought to be a few hundred kilometers or less in size, as the bursts last for only a few milliseconds
I think of multipath being about signals bouncing off other objects (reflection) and bending through media (refraction) before reaching the receiver. At the cosmic scale, I'm guessing multipath also involves gravitational lensing. Correct?
There is some possibility of gravitational lensing of FRBs and people are definitely searching for it. However, in this case it is refraction caused by variation in the density of the ionised gas between us and the source (within our galaxy, the host galaxy, and at lower densities in the intervening medium).
You just made me realize that it would be cheaper for an advanced civilization to send a message light years away by altering the medium through which the signal passes than to control the source directly, e.g. a neutron star.
This is a good question. FRBs pose a lot of challenges for follow up because most of them are not observed to repeat (this doesn't mean they don't repeat, just that they haven't been seen to). So you see them for a few seconds and then they're gone. To follow up, you need to know where exactly to look, and most of the instruments like CHIME used to discover FRBs don't have the resolution to see exactly where on the sky it was. You can maybe pin point it to within 1/4 degree, but need more like 1000th degree resolution to meaningfully follow up in other wavebands.
The most useful follow up has been for repeating FRBs. What happens there is that the discovery telescope tells you were it is roughly, and you know it repeats, so you can point a high resolution radio telescope (something like https://www.evlbi.org) to get a more precise location and then you can follow up with other telescopes.
One thing telescopes like CHIME are trying to do in the near future is to build their own long baseline station to give much higher resolution, such that they can get localisation on bursts which don't repeat, and do better follow up.
Thank you. I had been slightly familiar with fast follow up for SNs (that were detected optically), but their follow up times are much more forgiving than FRBs. The localization issue is also interesting.
I think astronomers often make it worse. I mean, we like thinking about why things are actually aliens as much as anyone else (LGM1 was already mentioned), and while we mostly try to restrain ourselves, every now and again a famous astronomer breaks and lets out a paper about it.
That's great to hear!
If some credible evidence of aliens did appear, where do you think it would come from? Tabby's Star like data? atmospheric spectra? FRB's? other?
Would absolutely love to hear your thoughts :)
That already happened. Living cells are nanotechnology. Something loaded with them impacted billions of years ago, and we're currently working on AI and rockets.
Make yourself intra-universally interesting enough that the alien construction management AI might instantiate a simulation of you from the cached info at some point. It's a strange sort of Darwinism, but it's all we've got.
An instantiation of me from a backup, however accurate, would be no use to my sense of having survived as I would have ceased to exist and not even be aware of the copy.
That's fine! People with your philosophy of self will just cease to exist, as they presumably will refuse to optimize for likelihood of being simulated, and those with a more permissive notion of self-identity will be the ones willing to adapt to the hellish computational circumstances.
(Of course, you could say that everyone's ceasing to exist, here, because your rules of what counts as a person and what's their copy applies to everyone. But please realize that, from the point of view of those who think having a copy survive is better than all of them dying, and is partial survival in some sense, that being simulated is a form of winning, even if you think both the person and the copy are deluding themselves.)
(Though I do wonder how you go about the day without having a nervous breakdown, given that your evolving state is probably quantized, or at least sliceable, meaning there's no great physical difference between your pattern shifting from one [smallfractionofa]second to the next, destroying the old one and replacing it with a new one, and your old pattern being destroyed and replaced somewhere else. It's not like your past self is aware of your future copy in normal life, either!)
(I'm not saying you're wrong; just that the situation is a lot worse than you think it is, and that we should all be living (and repeatedly dying) in absolute existential terror.)
I think there was a HN thread not that long ago about speculation that (at least some) viruses come to earth from space, so perhaps it is happening all the time.
This seems such a "flat earth" type of hypothesis. I mean viruses depend on their hosts 100% so them coming from somewhere with no hosts and successfully slotting in with new hosts just seems immeasurably unlikely.
I think it makes more sense if you think of a virus as a software update for a genome. The question is not how a virus made it here--fashioning a delivery mechanism should be easy for a civilization advanced enough to hack into the genetics of a species on a distant planet--but who are it's authors and what new features or bug fixes does it provide?
Flu-like symptoms are probably just an unfortunate side effect. Things break during updates, it's an unfortunate fact of life. Maybe when a critical mass of people accept the update, they'll start building a giant transmitter for FRB's to let the sender know that the update was accepted.
I'm sure others have written more, and more intelligent things, but my general thinking about panspermia is:
- it seems like a universal rule there are more small things than large things
- there are more small red stars than stars like our sun
- there should probably be more brown dwarfs than small stars
- there are more small planets than large ones
- planets can and do form without stars
- planets should outnumber stars, and planets without stars should outnumber planets with stars
- there are probably more oceans below the surface of objects in our solar system than on the surface
- the universe existed for a long time before the solar system
...so it kind of seems intuitive to me that life should have developed underground where there's warmth from radioactivity and water, on countless free floating planets over billions of years and occasionally one of those gets blown to bits and something like that seeded our unusual planet.
...and it doesn't seem entirely implausible to me that there should be so much biological material in space that we get a certain amount all the time like micrometeoroids.
Imagine you're arbitrarily close to the physical limits of technology. You do or could understand how living things work, down to the molecular level, for example, and know how to engineer self-replicating machinery analogous to DNA. At the very least, you could build a 'spaceship' that can grow something at least as efficient as people, who can replicate however and disassemble earth for raw materials. Presumably, you can do much better, and you end up with something like a self-packaged deployable technological superintelligent ecosystem.
Haha, nah, it was more the general idea. An amalgam of sci-fi. Greg Egan had a story where an advanced civ sends a gram-sized slug into the gas giant of a solar system, which bootstraps to machinery that 3d prints people and machinery, which is a plausible enough inspiration that I can give it here. Just remove the implausible 'nobody just decides to go bacteria-mode' aspect from Egan's far-future stories.
It's not the Egan book but Accelerando by Charles Stross is my favorite near-current day up to post-singularity book and it covers topics like this in a fantastic and fun way.
I haven't seen the original paper (maybe that should've been linked instead?), but the MIT press release is dripping with "Not it's saying aliens..." innuendo.
It's kind of hypocritical to use nod-wink-aliens-clickbait to drum up media attention, then ridicule the first rube who asks if aliens could possibly be involved.
That's a fair comment. I mostly think the MIT press release is pretty good and doesn't go down that route, except for the title, which is definitely hinting at it.
Also agree that it would make sense to replace the link with the actual paper, or an article about it. University press releases are mostly there to play up their own contribution.
I'm not super involved on the FRB side of CHIME, so I'm not 100% clear what is public and what isn't. But you can an idea from public info around the internet. I think the last total number made public was over 700 in March this year, and the previous one 30 in October 2018 (https://aasnova.org/2020/03/13/chime-detects-even-more-repea...).
Yeah, that's definitely one of the main hypotheses. There aren't any other repeating FRBs known to do this yet, so how general a mechanism this is, is not known.
In order to maximize impact. Press doesn't want to talk about this unless there is an embargo, otherwise they might be 'late' in which case they would rather not mention it at all (and not have to spend costly journalist time)
The more powerful technology provides the more powerful chips and telescopes and microscopes. On the basis of new data obtained with the help of new devices, new theories are created that help in creating even more microscopic components, which will help in creating even more powerful devices recursively. The singularity in the action of CHIME and AI made it possible to determine the signal; a major breakthrough is coming in all areas. Interestingly, somewhere there is a miscalculation when we can look into the space using a smartphone in real time? Any related theorems?
Assuming that it is aliens, for a moment, we can not know if these aliens are friendly or hostile, right? So, given that there is a 50/50 chance of them being hostile, and given their awesome show of strength, the precautionary principal dictates that we not advertise our presence too loudly.
They wouldn't know about us for 500 million years, assuming we could emit a strong enough signal for them to detect that far away. Any aliens that could actually pose a threat would probably be close enough to pick up our emissions anyway.
Since it hasn't come up yet: whenever a new astronomical phenomenon is detected, people think "Aliens!" as the reason.
In fact, when the first pulsar was discovered, it was (somewhat jokingly) called LGM-1 for "little green men".
I'm sure the news hype cycle will come up with similar ideas this time, and I'm just as sure that we'll find a perfectly reasonable explanation not involving intelligent, extraterrestrial life forms.
There was a time when people thought a ball of fire moving across the sky every day must be alive. The universe is full of strange phenomena perfectly explainable by physics. This is no different.
It's really not "perfectly" explainable by physics since we don't understand all aspects of physics yet. If you said "mostly" explainable by physics I would believe you.
Also, if an alien happens to be shining a beam at us rhythmically, that's also "explained" by physics but we won't actually know if the source is a natural phenomena or an alien shining his super flashlight at us.
Of course life at a deep level is just physics. But given that the information content of this signal is relatively low (regular patterns of repeats) and that the amount of energy it requires is immense, I'd bet much more heavily on a natural phenomenon than life-directed activity.
I’m not saying there’s evidence, I’m just pointing out that it’s a strange dichotomy to say that one one hand, we have explainable phenomena, and on the other hand we have extraterrestrial life. If we ever do find proof of it, I don’t understand why the assumption should be that it won’t be explainable.
The problem is, any form of intelligent life that exists in the same universe as us is going to have to be able to be explained by physics, since that’s what physics does - explain the way the universe gives rise to the phenomena in it which we observe. I mean, if we detected signs of intelligent life that can’t be explained by physics, that either means we have some new physics to discover, or physics has to give up because it turns out there is a form of life not subject to its rules.
Some of the earliest radio broadcasts are Hitler's speeches, as well as other world leaders preparing their nations for global conflict. So there's that.
That would be TV broadcasts as I’m guessing everyone here seen Contact.
Ironically in 1948 when FM was standardized and countries were assigned spectrums Germany wasn’t really invited as it wasn’t a state for that short period and wasn’t assigned a spectrum so they started broadcasting in VHF because that wasn’t covered by the Copenhagen Agreement.
A few years later people realized that VHF was supper efficient for FM unlike AM and (W)Germany ended up holding all the cards.
This is why (primarily older) VHF FM radio compatible receivers in Europe will have UKW FM or UKW option in the turner which stands for Ultrakurzwelle (Ultra short wave) that was before UHF was standardized above the VHF spectrum.
Alien dad goes windsurfing with SETI daughter, but the only evidence he leaves that it's not the hoax of some rich bald dude is 18 hours of static, so the audience can have both their faith and science, but no blackhole for Matthew McConaughey.
There's a story in which aliens unexpectedly destroy nearly everything in the solar system and when asked why, they explain that they received transmissions of Star Trek episodes and people singing "We Are The World" and so they put together the fantasies of galactic domination with the idea that humans might be close to global unification, and decided it was time to apply a bug bomb to Earth.
In other words, the things we see as negative might not bother aliens much, if they mostly indicate we might destroy ourselves.
There's a few ways to do it (and the press release is surprisingly good and mentions most of them), but certainly one of the more obvious explanations is that the emitting object, is in a binary system with some other object, and that modulates the emission mechanism somehow.
I don't think either needs to be a black hole though. What I consider the most plausible candidate for emission is probably magnetars (i.e. neutron stars with extremely strong magnetic fields), and there's no reason the companion would need to be a black hole either, you just need a companion that gives a 16 day orbit and that's very easy to do with another star or neutron star.
Variable stars, something involving a cyclic phase transition (from silent to active and back). Something like the Type Ia supernova, where the dense white dwarf siphons off mass from its companion until it reaches the Chandrasekhar limit and bang.
Maybe, but perhaps not in the way you think. A source that emits radiation only at certain angles (think a stellar disco ball) would only "flash" us infrequently as we moved relative to it.
arxiv Jan 28 paper "Periodic activity from a fast radio burst source" [1] via Feb 7 Vice article [2] and Wikipedia "Canadian Hydrogen Intensity Mapping Experiment (CHIME)" page [3].
Obviously the weird, non-euclidean geometry of some vast and incomprehensible machine built by eldritch abominations. When the stars have properly aligned, we will understand its true purpose all to well.
There are a lot of cool concepts in those books, but the sophon faster-than-light communication that props up a lot of the story was a bit too much for me.
The theory of quantum entanglement is sound though, and it took a while for a single sophon to arrive before the FTL communication. Layman here, but I thought it was relatively had science/speculative fiction.
Give distances to pulsars with an arbitrary scale. The receiver can solve for the scale once they figure out which pulsars you are referring to. Identifying pulsars could be as easy as a pulse modulated with the frequency of the pulsar...
1) The one relative to the receiver of the coordinates
2) You start by explaining the encoding first, before sending coordinates, maybe by establishing X and Y axes as well as compass direction based on “landmarks” that should be visible from the receiver.
That’s the first thing that came to my mind at least.
My first thought was that this sounds like a pulsar, and I was surprised to not see that among the list of possible phenomenon. After looking it up, I still wasn't quite sure why these couldn't be pulsars. Is it because the period is much higher than typical pulsars?
The article suggests it could be a spinning neutron star, which is what a pulsar is. But a pulsar produces an extremely regular sequence of pulses. (Well, actually it emits a continuous beam of radio waves, but its rotation causes the beam to point towards any given observer at regular intervals.)
This article describes a source that seems to start and stop at regular intervals of several days (much longer than any known pulsar's rotational period) but within the active intervals, the bursts appear to be random. That suggests a more complex mechanism is at work.
I just throw some gasoline on the "It must be Aliens!" theory (to which I do not subscribe!) and point out that heavily compressed data looks random...
What protocol do you use to represent the sequence? Bytes, Morse, Amplitude modulation, frequency modulation? All of these combinations may appear random to one without the right codec.
You would need to set up the satellites in such a way that anyone receiving your message is viewing their orbits edge on. Your satellites would also have to be extremely large and fairly close to your host star. And there’d have to be no dust between your star and the receiver.
As a method to communicate with people you don’t know exist, it’s not very good because chances are they won’t be viewing your satellites edge on. For people you know are there, it’s needlessly complicated and expensive.
If you’re going to go to the trouble, you’d be better off making a Dyson swarm and cloaking your star completely. You’d get energy back and be just as detectable for a civilization that thought to compare visible and IR sources (which some Earth scientists have done, with negative results).
Pulsars aren't 100% ruled out, but I think they're considered reasonably unlikely. The problem is mostly the apparent brightness. If you place almost any known pulsar (which are all in our galaxy) at the in the host galaxy of a localised FRB which(only a fraction of FRB's do we have measured distances for, but they're all quite far away), if would be far too dim.
The only exception to this is the Crab pulsar, which is observed to occasionally have "giant pulses" which are 1000s of times brighter than a typical pulse. If you put the a somewhat brighter version of the Crab pulsar in an FRB host galaxy at the low end of the known distances, you might just about be able to see it.
Earth has had life for more maybe as long as 4 billion years, and in all that time there has been less than 200 years when a species had the intelligence, the motivation, and the technological advancement to send communications into space.
I know the odds of this being life are (literally) astronomically low, but every time I hear news like this, I can't help hoping there's another species out there that found the will & the way to reach out.
Same feelings. It's never aliens, but it sure would be cool to meet a benevolent super advanced species or catch an intergalactic soap opera with octopus people. Really, any indication that we're not alone.
Given the size of the Universe, I would guess this as well 10/10, but so far we have zero evidence.
I wonder if we're all destined to stay within our own solar systems due to the light speed barrier, or if we'll ever figure out how to do FTL or bend space. It's frustrating that we can't seem to break out of our tiny bubble.
Maybe there is a prime directive that has nothing to do with a species achieving warp, but instead attempts to see if a species can work together on a planetary scale to tackle disease, hunger, energy, climate...etc? If so, we're doing a poor job, but are making progress.
Isn't it strange that the periods mentioned are integer multiples of days?
Don't known much about astronomy, but day as a unit of time is just a constant specific to our particular solar system. I guess a function of the sizes of the sun and the planets here. There should be nothing special about it. To think that 500M light years away there is something that has similar time proportions to be observed here as periodic is amazing by itself.
The period is 16.35 +/-0.18 days [1] so it's not exactly 16 days. The unit days is just the next best convenient unit to use for this range of time scale. 392 hours +/- 4 hours just isn't as intuitive as 16 days.
So the period is neither an integer multiple of days, nor exactly the same each time. There's some small variance involved - about 1%.
If aliens did exist, they would probably compress their communications. And they might use a fault tolerant infrastructure like TCP/IP. In either scenario, real communications would not be periodic but closer to random noise. Has anyone performed a Zipf plot or calculated shannon entropy of non-periodic radio signals?
TCP over radio? Direct communication by is the simplest implementation. Encoding a signal further seems counter intuitive, as opposed to a short repeating beacon that serves initial groundwork for a handshake. If the signal is supposed to cross vast interruptible distance, the bodies interrupting a continuous straightforward signal would appear periodic to the receiver.
Exactly. If you wanted to get someone's attention, you make your signal something that would standout from all of the background noise. If someone send a RCPT signal back, then you could consider sending a more complicated signal.
Maybe the transmitter is located far away from their civilization's main location.
It should be a stronghold, just for comms, fully expendable, probably with no information in any local hard/soft/wetware about where they actually reside.
If we answer, we would be probably be talking to "a phone tapped to another phone"
My pet theory for a while has been that they use point-to-point communications (lasers), rather than wasteful omnidirectional radio waves, so that you have to get very lucky in order to eavesdrop on them.
> This new FRB source, which the team has catalogued as FRB 180916.J0158+65, is the first to produce a periodic, or cyclical pattern of fast radio bursts. The pattern begins with a noisy, four-day window, during which the source emits random bursts of radio waves, followed by a 12-day period of radio silence.
The astronomers observed that this 16-day pattern of fast radio bursts reoccurred consistently over 500 days of observations.
I wonder how these aliens manage to work only for 4 days and then rest for almost 2 whole weeks. They must be quite advanced.
Let's run wild some imagination. So 500 million light years as distance, meaning it started at least 500 millions years ago. Dinosaurs weren't existing back then. Imagine a civilization which has this energy output that is detected 500 million light years away. Wasn't some quote where a type 4 civilization technology is indistinguishable from natural phenomenons?
Shouldn't they be able to discriminate the type of object (single star with orbiting planets that obstruct radio waves, or dual star plus planets where the emitter itself also moves around an orbit) by analyzing the received carrier frequency and see if it's also modulated by a much lower frequency (Doppler effect) compatible with orbital motion?
FRBs don't really have a "carrier frequency" in that sense. The radio burst occurs a broad range of frequencies, which can vary substantially from one burst to the next (there are graphs of this in the paper linked above). But there's no sharp peak that can be accurately measured, as far as I know.
And even if there was, we don't understand the mechanism behind FRBs, so we wouldn't necessarily be able to distinguish a Doppler shift from some other effect that caused the frequency to change.
If it’s regular like clockwork it’s nothing but a cog in the universe we’re looking at, all in all interesting to study.
Next irregular signal will be even more interesting though that does not necessarily imply alien communication
To be slightly fair, the policies of the journals have a lot to do with this. I'll try and explain:
This paper was submitted to Nature as it would be fairly high profile, and Nature does now allow you to put in on the arXiv at submission, which was done in January. Since then it has been going through peer review, and being queued up to get published in the journal which finally happened on June 17th. However, during that whole time there is a press embargo. So although you may have seen it back in January, that was because a few outlets picked it up by scanning the arXiv themselves, and no one within the collaboration has been allowed to talk about it to the press, and no universities to publicise it in the intervening time. That embargo has presumably just been lifted which is why this is all coming out now.
Because of the embargo you wouldn't have seen quotes and comments from people involved in the initial coverage back in January, and even if I'd noticed it getting posted to HN back in January I would have not been allowed to comment on it like I'm doing now.
The search for aliens within aliens just insane. They've communicated with us for years. The idea itself a communication. It's matter of time until we get more civilized.
It seems like so long ago the paper actually went public onto the arXiv, but I guess the press embargo just ended.