Wikipedia:Reference desk/Archives/Science/2019 August 13

= August 13 =

Depression and insomnia
Is there a connection between depression and insomnia? Freeknowledgecreator (talk) 00:24, 13 August 2019 (UTC)


 * Insomnia is common among the depressed.. Count Iblis (talk) 00:51, 13 August 2019 (UTC)


 * The link is complex, and may go in both directions: . SinisterLefty (talk) 00:07, 15 August 2019 (UTC)

How is the rate of exoplanets shaping up?
I wonder if anyone knows or has a good link comparing predictions of the number and consistency of Milky Way planets according the (is it the Standard Model in this circumstance?), expectations, and the numbers and consistency according to what we are finding in the places we are looking? ~ R.T.G 17:58, 13 August 2019 (UTC)


 * It's just out of curiosity... I'm sorry if your swamped I didn't look... ~ R.T.G 17:59, 13 August 2019 (UTC)


 * Basically, as far as we can tell, every star in the galaxy should have planets around it (statistically speaking).See here. That is, since we have come up with methods to find planets, around just about every star we expect to find them, we find them.  You can see at the Wikipedia article Exoplanet, there are some statistics on the number of planets that have been discovered, the general history of their discovery, etc. etc.  -- Jayron 32 18:12, 13 August 2019 (UTC)


 * Thanks Jayron32. I suppose if there was significant divergence they'd report it as such a lot. ~ R.T.G 18:35, 13 August 2019 (UTC)


 * One canonical source of data is NASA and CalTech's Exoplanet Archive. This website includes scientific summaries, statistics, and detailed data access, largely derived from research associated with the Kepler space telescope exoplanet research, as well as the currently-operational TESS spacecraft program, designed as a small satellite to follow the Kepler mission.
 * In a simplified summary: as of this writing there are more than 4,000 exoplanets whose observations are marked as "confirmed," which broadly means that they are published observations that have been scrutinized in peer-reviewed literature. Beyond that number, there are many (around 3,000) additional candidate observations for which the data is still being analyzed, or for which the signals are present but inconclusive.  Consider this analogy: it might be difficult to read the license-plates in a series of blurry photographs of automobiles, so there is a spectrum of confidence about exactly how much we agree about the numbers on the 3,000 "most blurry" data sets.  On the other hand, there are over 4,000 planets for which the "picture" is indisputably clear.
 * As for how these numbers compare with predictions: I'm not sure there ever had been meaningful, data-driven predictions about planetary formation rates: we understand the basic science by way of our stellar evolution models, but we had very little statistically-relevant data. For this reason, we typically just leave fp unspecified.
 * If you want to compare the discovery rate against its "predicted" discovery rate, have a look at the pre-launch science that was published by the Kepler mission scientists. For example, here is the publication list of one William J. Borucki, Kepler's principle investigator.  This 2003-vintage SPIE paper, The Kepler Mission..., details why the instrument was designed in this way: specifically, it was designed with parameters that could yield "statistically-significant" observations - and those statistics were motivated by prior research.
 * Nimur (talk) 15:17, 14 August 2019 (UTC)


 * Note that this Q touches on two variables of the Drake equation:


 * fp = the fraction of stars that have planets


 * ne = the average number of planets that can potentially support life per star that has planets


 * If those numbers are high, that would increase the number of civilizations out there we might communicate with. Thus, to account for the apparent lack of such civilizations we have discovered, we must adjust other variables of the equation downward.  SinisterLefty (talk) 04:22, 15 August 2019 (UTC)


 * How about not adjusting the priors without more evidence about the other factors you're adjusting them for? Your argument leads to the silliness where every time they checked a place where Saddam might have had some weapons they just said that he must be even more evil and cunning than they first thought. Dmcq (talk) 11:53, 15 August 2019 (UTC)


 * No, just the reverse. If we had an equation for predicting how many WMDs he had, something like C + B + N = T (chemical + biological + nuclear = total), then not finding the total we expected would require lowering the C, B and N values to make the equation fit. (Of course, in most cases, the C, B and N could be observed directly, but there could be cases where "special weapons", like rockets, that were guarded excessively to be conventional warheads, were observed.)    SinisterLefty (talk) 12:47, 15 August 2019 (UTC)


 * Can't really add anything but just to express appreciation... In a similar vein, supposedly the calculations on the Big Bang are a great fit, except for this big gap some time shortly after the main event, which could never be satisfactorily explained, but otherwise the theories are a great fit all the way through. So it's just interesting if there are gaps in other relative theories, thanks again. ~ R.T.G 11:32, 18 August 2019 (UTC)

Energy and matter
We are taught at school etc that neither enegy nor matter can be created or destroyed but only converted one into the other. Fair enough. So where did all the energy and matter come from at the very start of the universe? -- 80.2.20.134
 * Big_Bang  Eve rgr een Fir  (talk) 20:03, 13 August 2019 (UTC)


 * From the hand of God, of course. ←Baseball Bugs What's up, Doc? carrots→ 20:42, 13 August 2019 (UTC)
 * Ok bb, so where exactly was god sitting when he created the big bang? Please be serious in answering serious questions. Thanks.80.2.20.134 (talk) 22:00, 13 August 2019 (UTC)
 * Sorry, but science cannot answer this question, as of today, and most probably never will. You enter metaphysics and one of its most fundamental question: Why there is anything at all? I personally stand more or less with Spinoza : god was (and still is) the whole fucking universe. But then again, this is just one among many solutions, we have no way to say one is better than another. Gem fr (talk) 00:17, 14 August 2019 (UTC)


 * See also here. Count Iblis (talk) 01:10, 14 August 2019 (UTC)


 * The mass+energy of the universe might always have been zero if you count gravitational potential energy as negative, as most physicist do, with zero at infinity. You might like to read Vacuum genesis and Zero-energy universe.  Stephen Hawking said "We might decide that there wasn't any singularity. The point is that the raw material doesn't really have to come from anywhere. When you have strong gravitational fields, they can create matter. It may be that there aren't really any quantities which are constant in time in the universe. The quantity of matter is not constant, because matter can be created or destroyed. But we might say that the energy of the universe would be constant, because when you create matter, you need to use energy. And in a sense the energy of the universe is constant; it is a constant whose value is zero. The positive energy of the matter is exactly balanced by the negative energy of the gravitational field. So the universe can start off with zero energy and still create matter. Obviously, the universe starts off at a certain time. Now you can ask: what sets the universe off. There doesn't really have to be any beginning to the universe. It might be that space and time together are like the surface of the Earth, but with two more dimensions, with degrees of latitude playing the role of time".   Dbfirs  14:43, 17 August 2019 (UTC)


 * I was under the impression that gravity was a bi-product of mass warping space time. Without space-time, there can be be no mass, without mass, space-time cannot be warped. Hence, no gravity and therefore, no gravitational fields. Unless the dilemma of quantum gravity was cracked when I wasn't looking. So I've never understood the explanation of potential negative energy from gravitational fields before the big bang created space-time. Unless we can verify quantum gravity, or the existence of other universes to supply these gravitational fields. It seems to me to just be fancy guesswork. Gem is correct, science cannot answer this question yet. — Preceding unsigned comment added by Timfitz42 (talk • contribs) 22:44, 21 August 2019 (UTC)