[ExI] tabby's star dimming again

John Clark johnkclark at gmail.com
Wed May 24 22:31:01 UTC 2017


On Tue, May 23, 2017 at 9:49 PM, Stuart LaForge <avant at sollegro.com> wrote:

​> ​
> Irregardless of whatever explanation is found for it, Tabby's Star will go
> down in history as one of the luckiest breaks in all of science.


I
​have a hunch​
 the explanation will be more mundane. On January 26 2016  Tabetha
​ (Tabby)​
Boyajian
​ and her team wrote a paper:​

https://arxiv.org/pdf/1509.03622.pdf

​It hypothesized that the dimming was caused by something like a giant
comet in an elliptical orbit of 750 days and predicted (remember this was
over a year ago) that it would start to dim again in May 2017, this very
month. Just a few days ago it was reported that from the start to the
finish of a single night of observing Tabby's Star dimmed by 2%. We should
know more soon, if it's a cloud of dust and gas (like a comet) the dimming
should be greater at bluer wavelengths than red, but if it's a solid object
the dimming should be the same at all wavelengths,

​> ​
> Let's please constrain the search space to our own galaxy.


​Why?​



> ​> ​
> Apart from the
> ​ ​
> closest galaxies in our own cluster, we would have very little chance of
>> noticing engineered galaxies in the rest of the universe.


​Why? A engineered galaxy containing 100,000,000,000 Dyson Spheres would be
easily visible even 5 billion light yeas away, but we see no such thing,
instead we observe billions of suns in billions of galaxies radiating all
their valuable energy uselessly into the cold of empty space.


> ​> ​
> Most of the
> ​ ​
> galaxies could have been Dysoned off back in age of the dinosaurs and we
>> would be none-the-wiser for a few billion more years.
>

​Dinosaurs were around until yesterday, or rather until 66 million years
ago, but in a universe 13.8 billion years old that amounts to pretty much
the same thing.

​> ​
> Notice that Tabby's Star located in the constellation Cygnus is almost in
> the same orbit as we are around the galactic nucleus. That's amazing!
>

​If it's only 1480 light years away it would pretty much have to.​


​> ​
> most of the galaxies we can see didn't have metals when the light
> we observe left them. Without metals how do you engineer anything let
> alone galaxies?


​That's true for the most distant galaxies we can see, but not for the many
billion we can see that are closer than 5 or 6 billion light years. ​
    ​

> >
>> ​> ​
>> For intelligence to form on a planet life may have to
>> ​ ​
>> start freakishly early, if not their sun might not give Evolution enough
>> ​ ​
>> time to produce intelligence before it dies of old age. After all, in the
>> ​ ​
>> nearly 4 billion year history of life on this planet Evolution only
>> ​ ​
>> managed to come up with a technological civilization once, and it
>> ​ ​
>> only happened a few thousand years ago.
>
>
> ​> ​
> True but evolution is a stochastic process like a random walk. You might
> ​ ​
> never reach your destination or you might get lucky and reach it in the
> ​ ​
> first few steps. The point is that we don't know if we are early, late, or
> ​ ​
> somewhere in the middle.


​We know for sure that Earth wasn't late in inventing life, it started
almost as soon as liquid water appeared, it simply couldn't ​
​have happened sooner. As for intelligent life, either we're the first or
something destroys all technological civilizations when they get to about
our level.

​> Why [should photosynthesis occur more readily under a hotter star]? If
>>>>   it's a planet that can support liquid ​water and its sun is
>>>>  brighter than ours then it must be further from it's sun than we are from
>>>>  our sun. So from that planet the disk of the sun would look more
>> intensely
>>>>  bright than what we see from our planet but it would also look smaller,
>> so
>>>>  the total amount of solar energy reaching the surface would be the same
>> on
>>>>  both planets.
>
>
> ​> ​
> Yes but not all solar flux is created the same. In photosynthesis it is
> the blue wavelengths in the neighborhood of 450 nm that do most of the
> heavy lifting. A hotter more massive star should have it entire spectrum
> shifted blueward.


​And that means the star would produce more ultraviolet radiation which
destroys biological molecules.


> Thus more "high calorie" light for the plants to gobble
> ​ ​
> up. The increased vigor of plant growth should cascade up the food chain
> ​ ​
> such that even apex predators should have more offspring and thereby
> ​ ​
> evolve faster.
>

​
The time in Earth's history where the total amount of biomass
​ w
as greatest occurred
​
during the
​
Carboniferous
​
Era which ended about 80 million years before the first dinosaur. Back then
there was a huge amount of plant life, so mush so that there was nearly
twice as much oxygen in the air as now (forest fires must have been a
bitch) and about 3 times as much CO2; Yet
​
the most advanced land animals at the time were 9 foot
​
millipedes, dragonflies the size of falcons, and 18 inch
​
long cockroaches
​.​

.
And
​
I think it would be
​
very unlikely
​
sea creatures
​
could ever
​
develop technology. The laws of Newtonian Physics were hard enough to
discover
​by​
 humans who lived in a
​ ​
n
​
atmosphere not a vacuum, but it would be
​
enormously
​
harder
​
to do so
​
under water
​
where
​
it would look like
​
things
​
never
​
move at the same speed unless a force is constantly applied, and
​
smart
​
 fish wouldn't have the motions of the stars and planets to help them
figure out basic physics. Even humans would never have discovered Quantum
Mechanics if they hadn't figured out a way to make a vacuum
​
so the
​y​
could perform experiments
​ in it​
.
​
And intelligent fish would lack fire
​
, so they'd have no way to work metal, no iron or bronze or even copper
tools, and no steam engines
​
to start a industrial revolution.

​ ​
John K Clark
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.extropy.org/pipermail/extropy-chat/attachments/20170524/d9e1dc08/attachment.html>


More information about the extropy-chat mailing list