
Mysterious deep-space flashes repeat every 157 days - hhs
https://www.space.com/mysterious-fast-radio-burst-repeater.html
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mandarg
Here is an index of different theories that astrophysics departments have
developed to explain these FRBs (Fast Radio Bursts):
[https://frbtheorycat.org/index.php/Main_Page](https://frbtheorycat.org/index.php/Main_Page).
There are links to all of the corresponding papers as well.

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airstrike
Thanks. Found what I was looking for: "Fast Radio Bursts from Extragalactic
Light Sails"

[https://ui.adsabs.harvard.edu/abs/2017ApJ...837L..23L/abstra...](https://ui.adsabs.harvard.edu/abs/2017ApJ...837L..23L/abstract)

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raghava
> Researchers monitored the known repeater FRB 121102 with the Lovell
> Telescope, a 250-foot-wide (76 meters) radio dish at Jodrell Bank
> Observatory in England, over the course of five years. They found strong
> indications of a 157-day activity cycle; 121102 seems to flare up for 90
> days and then go silent for 67, the team reported in a new study.

> It's unclear what's behind such cyclic activity, though scientists do have a
> few ideas. For example, periodic flare-ups could be caused by a wobble in
> the rotational axis of a highly magnetized neutron star known as a magnetar.
> Or they could be linked to the orbital motions of a neutron star in a binary
> system.

Could this be the Dzhanibekov Effect ? Funny I just stumbled upon it today!

[https://www.youtube.com/watch?v=1VPfZ_XzisU](https://www.youtube.com/watch?v=1VPfZ_XzisU)

If Earth can maintain a stable axis, such wobbly oscillating axis could be
that star's "normal". Just guessing! Or may be am too wrong. I am not a
physicist!

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simonebrunozzi
> I am not a physicist!

Man, don't be too modest. With these few lines I'd be tempted to award you a
Nobel prize if I were the judge :)

(exaggerating a bit, but more seriously: you seem to have your chops in this
department).

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Vysero
The idea that aliens would use these to propel ships is rather ludicrous, and
highly unlikely. The nearest galaxy is 25k light years away so even at the
maximum speed it would take 25 thousand years to travel here.

That being said, it must be something exceptionally energetic.. wish I could
see it.

~~~
marcinzm
Why do you assume they need to travel between galaxies? They could be going to
the next solar system over and we're simply seeing the leakage of their
propulsion. Just because the light travels across galaxies doesn't mean it's
purpose is to travel across galaxies. Moreover, a species that can unleash
this much energy has probably conquered such things as mortality and age
related decay.

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Vysero
That's a good point perhaps I jumped to conclusions.

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gremlinsinc
you also assume they're traveling AT or NEAR light speed, they could be
traveling many times that OR not traveling via speed at all, but warping space
and literally folding it over on itself and going THROUGH space like basically
creating a controlled wormhole.

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Vysero
No they couldn't actually. You didn't read the article.. here it is:

[https://www.space.com/35996-fast-radio-bursts-powering-
alien...](https://www.space.com/35996-fast-radio-bursts-powering-alien-
spacecraft.html)

the suggestion is that they would be gathering the waves in a light sails.
Also you can't travel faster than light, end of story. Warping space or
traveling through "wormholes" is not faster than light travel.

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codefreakxff
Oh man, I don't want to get into an argument on HN. But you didn't really read
the previous comment with a generous eye. The poster never mentioned "faster
than light" travel at all. In fact, they specifically called out AT or NEAR
light speed, and then gave wormhole travel as an example of "not traveling via
speed".

~~~
marcinzm
gremlinsinc literally said "they could be traveling many times that" in
respect to "AT or NEAR light speed." As in they could be traveling many time
faster than light. He didn't use the exact phrase "faster than light" but his
meaning is pretty clear.

~~~
gremlinsinc
Transportation technically is faster than the speed of light, because if
travelling at the speed of light you get to point B in 5 years, and by using a
warp drive/worm hole device you get their in 3 days, you've traveled faster
than light, doesn't matter if you cheated using physics, you still got their
in a fraction of the time. Sure you're 'speed limit' didn't exceed the speed
of light, but the distance/normal travel time DID exceed the speed of light,
so it's just semantics.

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kristopolous
The stable period is fascinating. Celestial machinery is an actual thing.

~~~
kitd
Even more so when the period is at normal everyday human timescales.

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raxxorrax
Astronomy is certainly an endeavor of multigenerational patience. Mazing and
frustrating at the same time.

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cgriswald
Astronomers substitute "lots and lots of similar objects at different stages
of evolution" for time. Most of the timescales involved are longer than the
time humans have existed on Earth and much longer than civilization.

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zachrip
What if it's something simple like a galactic lighthouse of sorts? Not sure
why I'm being downvoted. Lighthouses use directional light and if you're
stationary you'll see the light at certain increments of time. An advanced
race might be saying "don't go here" or "be careful." Just like we do for
ships here.

~~~
imglorp
There are lots of naturally occurring ones such as pulsars, enough to the
point they could be used for 3D navigation, if you can find your distance to
them.

It's an old idea: Pioneer and later spacecraft have a plaque showing our
location relative to distances to pulsars we can see from Earth.

[https://en.wikipedia.org/wiki/Pulsar](https://en.wikipedia.org/wiki/Pulsar)

[https://en.wikipedia.org/wiki/Pulsar#/media/File:Pioneer_pla...](https://en.wikipedia.org/wiki/Pulsar#/media/File:Pioneer_plaque_sun.svg)

edit: I guess if you're a Type 3 civilization with nothing better to do, you
wouldn't have to set up lighthouses but you could better direct your attention
to moving galaxies around or whatever.

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privong
> There are lots of naturally occurring ones such as pulsars, enough to the
> point they could be used for 3D navigation, if you can find your distance to
> them.

There's work towards this, from the X-ray emission of pulsars[0]. I don't
think you'd need a precise distance to the pulsars to measure your own
position, as long as you're measuring your own position relative to some other
object (e.g., Solar System barycenter). If it's a relative measurement then
you should be able to determine that by comparing the time-of-arrival (TOA) of
the pulsed emission from multiple pulsars with the TOAs at Earth.

[0] [https://en.wikipedia.org/wiki/X-ray_pulsar-
based_navigation](https://en.wikipedia.org/wiki/X-ray_pulsar-based_navigation)

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kabdib
Pulsar glitches are a thing, here's a great resource:
[http://www.jb.man.ac.uk/pulsar/glitches.html](http://www.jb.man.ac.uk/pulsar/glitches.html)

I'd worry about pulse identification over any significant period of time.

~~~
privong
And pulsars spin rates slowly change over time do to energy losses.

But I don't think these things would cripple a pulsar-based navigation system.
Presumably any network of pulsars used for this purpose would be regularly
monitored and timing solutions would be updated regularly. The updated timing
solutions could be transmitted as-needed.

At any rate, a robust navigation network of pulsars would need a sufficient
number of sources to guard against glitches breaking the navigation system.

~~~
TeMPOraL
Also, in context of an alien civilization finding our XX century probes a
million years from now, I think they could reconstruct the location anyway -
I'd assume there would be only one combination of pulsars you could pattern-
match to what's on Voyager plaques, even if each of them shifted in frequency
a bit.

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throw1234651234
Do we have any way to know whether or not these are directional?

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aruggirello
AFAIK, not directly. The only way possible would be to observe one behind a
gravitational lens. That would appear as multiple sources, allowing us to
observe the object from _slightly_ different directions, confirming that the
flashes are indeed at least cone-shaped.

Edit: clarified

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bkrishnan
"They found strong indications of a 157-day activity cycle; 121102 seems to
flare up for 90 days and then go silent for 67, the team reported in a new
study."

Maybe there's nothing to it, but both 157 and 67 are primes.

~~~
slg
A "day" has no meaning anywhere but on Earth. So if you are going to make the
leap that the usage of primes is a sign of intelligence, you would also have
to believe that this message was meant for us and only us. However the burst
seems to originate from 3 billion light-years away so they would have had to
start sending the message very shortly after life began on the Earth. Seems
incredibly unlikely.

EDIT: Also an Earth day is not a constant value. It would have been much
shorter 3 billion years ago and this cycle wouldn't be repeating in prime
numbers. This theoretical alien intelligence would therefore need to not only
be able to recognize life on Earth in the first few hundred million years it
existed. It would also need to be able to accurately model the Earths orbit
over the next 3 billion years in order to customize the message for when it
would be received. All that work to send the message and they still needed to
luck out that the 3 billion year journey happened to reach us at nearly the
perfect time for our technology to advance enough so we could hear it.

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saas_sam
It wouldn't have to do any of that if it was simply keeping an activity:non-
activity ratio that resulted in 2 primes. I'm not sure to what degree of
precision this flashing is happening but if it's very precise then there you
go. 2 primes result no matter what your day/timescale/number system is.

~~~
SketchySeaBeast
But it's not, it's active for 90 days. You'd think they'd go for the trio.

~~~
ncmncm
Good one. It is rare that two primes can be added to get a third prime. And
one of them is always 2. :-)

~~~
SketchySeaBeast
Admittedly, the options are more limited.

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biolurker1
what can be sure is that they are not trying to make their presence known
because at then they would make them non-repeating on purpose

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womitt
Just the admin taking snapshots in case he has to roll back ;)

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isoprophlex
Imagine it's coming from a bunch of alien networking gear, sending packets of
data across galaxies...

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m00dy
then it hits the planet Earth and then package is now dropped

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zelphirkalt
The cavemen ate our packages again! Need to clean up that pipe at some point.

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myself248
It obstructs my view of Venus!

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perseusprime11
Every 157 days feels like travel time. Can we isolate everything that in the
Universe that takes 157 days from Earth and scanning the sky?

