<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><span style="font-family:arial,sans-serif">On Tue, May 23, 2017 at 9:49 PM, Stuart LaForge </span><span dir="ltr" style="font-family:arial,sans-serif"><<a href="mailto:avant@sollegro.com" target="_blank">avant@sollegro.com</a>></span><span style="font-family:arial,sans-serif"> wrote:</span><br></div><div class="gmail_extra"><div class="gmail_quote"><br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>Irregardless of whatever explanation is found for it, Tabby's Star will go<br>
down in history as one of the luckiest breaks in all of science.</blockquote><div><br></div><font size="4">I <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">have a hunch</div> the explanation will be more mundane. On January 26 2016 Tabetha<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> (Tabby)</div> Boyajian<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> and her team wrote a paper:</div></font><div><br></div><div><a href="https://arxiv.org/pdf/1509.03622.pdf" target="_blank">https://arxiv.org/pdf/1509.<wbr>03622.pdf</a><br></div><div><br></div><div><div class="gmail_default"><font size="4"><font face="arial, helvetica, sans-serif"></font>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, </font></div></div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>Let's please constrain the search space to our own galaxy.</blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">Why?</div> </font></div><div> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>Apart from the<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>closest galaxies in our own cluster, we would have very little chance of<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>noticing engineered galaxies in the rest of the universe. </blockquote><div><br></div><div><div class="gmail_default"><font face="arial, helvetica, sans-serif"></font><font size="4">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. </font></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><span style="font-family:arial,sans-serif"> </span><br></div></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"> <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>Most of the<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>galaxies could have been Dysoned off back in age of the dinosaurs and we<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>would be none-the-wiser for a few billion more years.<br></blockquote><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"><font size="4">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. </font></div></div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>Notice that Tabby's Star located in the constellation Cygnus is almost in<br>
the same orbit as we are around the galactic nucleus. That's amazing!<br></blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">If it's only 1480 light years away it would pretty much have to.</div> </font></div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>most of the galaxies we can see didn't have metals when the light<br>
we observe left them. Without metals how do you engineer anything let<br>
alone galaxies? </blockquote><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><font size="4">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. </font></div></div> <br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><span class="m_8146675306036746091gmail-"><font size="4">
><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div> For intelligence to form on a planet life may have to<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>start freakishly early, if not their sun might not give Evolution enough<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>time to produce intelligence before it dies of old age. After all, in the<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>nearly 4 billion year history of life on this planet Evolution only<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>managed to come up with a technological civilization once, and it<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>only happened a few thousand years ago.</font></span></blockquote><span class="m_8146675306036746091gmail-">
<br>
</span><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>True but evolution is a stochastic process like a random walk. You might<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>never reach your destination or you might get lucky and reach it in the<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>first few steps. The point is that we don't know if we are early, late, or<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>somewhere in the middle.</blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">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 </div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">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. </div></font></div><div><br></div></div></div><blockquote style="margin:0 0 0 40px;border:none;padding:0px"><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"></blockquote></blockquote></div></div></blockquote><blockquote style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex" class="gmail_quote"><div class="gmail_extra"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><font size="4">> Why [should photosynthesis occur more readily under a hotter star]? If<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div><span class="m_8146675306036746091gmail-"> it's a planet that can support liquid water and its sun is<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div> brighter than ours then it must be further from it's sun than we are from<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div> our sun. So from that planet the disk of the sun would look more intensely<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"></div> bright than what we see from our planet but it would also look smaller, so<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div> the total amount of solar energy reaching the surface would be the same on<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div> both planets.</span></font></blockquote></div></blockquote><div class="gmail_extra"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><span class="m_8146675306036746091gmail-"><br></span></blockquote><div class="gmail_quote"><span class="m_8146675306036746091gmail-">
</span></div></div><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>Yes but not all solar flux is created the same. In photosynthesis it is<br>
the blue wavelengths in the neighborhood of 450 nm that do most of the<br>
heavy lifting. A hotter more massive star should have it entire spectrum<br>
shifted blueward.</blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">And that means the star would produce more ultraviolet radiation which destroys biological molecules.</div></font></div><div> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">Thus more "high calorie" light for the plants to gobble<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>up. The increased vigor of plant growth should cascade up the food chain<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>such that even apex predators should have more offspring and thereby<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>evolve faster.<br></blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"></div>The time in Earth's history where the total amount of biomass<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> w</div>as greatest occurred<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>during the<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>Carboniferous<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>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<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>the most advanced land animals at the time were 9 foot<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>millipedes, dragonflies the size of falcons, and 18 inch<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>long cockroaches<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">.</div></font><br>.</div><font size="4">And<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>I think it would be<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>very unlikely<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>sea creatures<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>could ever<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>develop technology. The laws of Newtonian Physics were hard enough to discover <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">by</div> humans who lived in a<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>n<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"></div>atmosphere not a vacuum, but it would be<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>enormously<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>harder<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>to do so<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>under water<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>where<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>it would look like<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>things<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>never<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>move at the same speed unless a force is constantly applied, and<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>smart<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div> 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<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>so the<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">y</div> could perform experiments<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> in it</div>.<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>And intelligent fish would lack fire<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"></div>, so they'd have no way to work metal, no iron or bronze or even copper tools, and no steam engines<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>to start a industrial revolution.<br><br><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>John K Clark</font><div><span class="m_8146675306036746091gmail-il" style="font-size:12.8px"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"><br></div></span></div><div><span class="m_8146675306036746091gmail-il" style="font-size:12.8px"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"><br></div></span></div><div><span style="font-family:arial,helvetica,sans-serif"><br></span></div><div><span style="font-family:arial,helvetica,sans-serif"><br></span></div><div> <br></div></div></div></div>