Wikipedia:Reference desk/Archives/Science/2016 February 6

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February 6

List of people who have walked on the Moon

I just stumbled upon this article: List of people who have walked on the Moon. So, is it true that no one at all has ever walked on the moon, other than people from the USA? That seems odd to me. Joseph A. Spadaro (talk) 06:48, 6 February 2016 (UTC)

Well, it shouldn't be too much of a surprise, given that only the US has ever sent successful missions to the Moon, and the age of international cooperation in space travel didn't really get going until after Apollo was over. To me, maybe the sadder stat is that no one born after 1935 has ever walked on the Moon. I hope that will change. --Trovatore (talk) 08:15, 6 February 2016 (UTC)

Quibble: Only NASA has attempted manned Moon missions (as far as we know), but other projects have successfully landed there. —Tamfang (talk) 08:26, 6 February 2016 (UTC)

The Iron Sky link is fantastic. Cannolis (talk) 09:06, 6 February 2016 (UTC)

As for why, the only serious competitor to NASA, until recently, was the Soviet Union, and they didn't want to put in the massive resources it would take to get to the Moon, especially just to become the 2nd to land somebody there. They preferred to put their resources into places where they could be first, like first ship into space, first dog, etc. After all, the purpose of their space program was to prove to the world that they were #1, not #2. StuRat (talk) 14:52, 6 February 2016 (UTC)

Arguably, that's what the US was doing too...which explains why the USA never went back there after the Apollo program was ended. The USSR had plans to send men to the moon - they just dropped them once they knew they wouldn't get there first. (See Soviet manned lunar programs). If they'd kept to their schedule, they might actually have beaten the US to getting a man onto the moon by a matter of months - but the unexpected death of their chief rocket engineer, Sergei Korolev, due to cancer - and then financial cutbacks - threw enough delays into the program that allowed the USA to beat them to it...and within a very short span of that happening, the plans were dropped and buried as if they'd never happened. SteveBaker (talk) 16:09, 6 February 2016 (UTC)

And, as far as the first ship into space, there's been the suggestion that some in the US didn't want to be first, both to allow the Soviet Union to establish the precedent that overflying other nations was not a violation of airspace, and to gain the massive taxpayer support needed for future programs. StuRat (talk) 16:23, 6 February 2016 (UTC)

Got a ref for the second claim, on airspace? SemanticMantis (talk) 16:55, 6 February 2016 (UTC)

Here's a discussion at BBC News. StuRat (talk) 19:52, 6 February 2016 (UTC)

Even before we went, no small number of Americans thought it was a waste of taxpayer money. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:11, 6 February 2016 (UTC)

Yes, this is my point. After seeing that space ships were possible, and that the Soviet Union could launch them, this changed the minds of most US taxpayers. Later, JFK's speech certainly helped, too. StuRat (talk)

Many, especially in the older generation, argued it was a waste of taxpayer money even after we had achieved it. Their typical response to that accomplishment was, "So what?" ←Baseball Bugs ^{What's up, Doc?} carrots→ 08:29, 7 February 2016 (UTC)

Yeah, I never paid it much mind. I think I had assumed that other nations (especially Russia) had done so, just with much less fanfare than the US's "first" men up there. Joseph A. Spadaro (talk) 18:11, 6 February 2016 (UTC)

Well, the Soviets tried to land a man on the moon in the 60s, but they gave it up because their chosen booster had the rather unfortunate habit of exploding every time they tried to launch something with it (the second time, it blew up on the pad, completely destroying the launch complex in what was both the largest explosion in the entire history of rocketry and believed to be the largest man-made non-nuclear explosion ever, with an approximate explosive yield of seven kilotonnes TNT equivalent). Whoop whoop pull up ^{Bitching Betty | Averted crashes} 20:18, 6 February 2016 (UTC)

OMFG, that's almost half the yield of Hiroshima! I suppose that's not good for the launch complex. Wnt (talk) 00:37, 7 February 2016 (UTC)

Video of failed Cygnus CRS Orb-3 mission

To be fair - many new (and ultimately successful) rocket programs go through phases of blowing up...(although perhaps not as disasterously as the N1 did). It only takes one teeny-tiny design flaw to make that happen - and quite often one explosion is sufficient to enable the designers to figure out what needs to be fixed. So just because one or two prototypes had problems, you can't extrapolate from that to say that it would never have worked had they kept working on it. The very next launch attempt could have succeeded perfectly. Just so you don't think the N1 was unique in that regard, a commercial launch at the Wallops Island launch site (under NASA auspices) left a 60' wide, 30' deep crater where the launchpad was used to be. That happened in October 2014. — Preceding unsigned comment added by SteveBaker (talk • contribs) 15:59, 7 February 2016 (UTC)

Funny you should mention the loss of that Orb-3 flight of Orbital's Antares rocket, as its first stage was powered by Aerojet AJ-26 engines, which are refurbished, 40-years old, Soviet NK-33s which were originally intended for the N-1 moon shot rocket discussed above. An engine failed due to an explosion in its LOX turbopump. During the investigation, it was leaked that Foreign Object Debris had been detected in the turbopumps, possibly from desiccant left in a tank. The final report confirms the FOD, but states that "there is no clear forensic evidence that FOD directly or indirectly led to the E15 [engine] failure", and also reports on inadequate design robustness and a manufacturing flaw in the engine. See NASA Independent Review Team Orb–3 Accident Investigation Report Executive Summary. -- ToE 02:51, 8 February 2016 (UTC)

I'm shocked that your school paid so little attention to the history of the manned space program. Of course, I lived through it, so it was front-page all the time, until Congress stopped funding Apollo four missions short of its original intended duration. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:09, 6 February 2016 (UTC)

@Baseball Bugs: What time frame are we talking about? Late 50's and early 60's? Joseph A. Spadaro (talk) 03:09, 7 February 2016 (UTC)

Yes. Of course that wasn't "history", it was "current events". ←Baseball Bugs ^{What's up, Doc?} carrots→ 08:27, 7 February 2016 (UTC)

OK. That was "before my time". And I guess it lost all of its "sexiness" (newness) as a topic in school by the time I got there. Joseph A. Spadaro (talk) 19:44, 7 February 2016 (UTC)

I've noticed that there's a hole between current events and history. For example, if you were in high school during Watergate, it was probably discussed as current events. And if you were in high school by the 1980's, it might have made it into the history books by then. But if you were in high school in the late 1970's, it was no longer a current event, and wasn't yet in the history books, either. StuRat (talk) 19:54, 7 February 2016 (UTC)

posting by banned user removed.

Apollo was expensive, but not that expensive. Per Apollo program#Costs, each Saturn V launch in 1970 cost $375M, against total outlays that year of $195B (see here). I don't know whether the $375M was a marginal or average cost; obviously average cost will be much higher than marginal.

The total cost of the Apollo program altogether was estimated in 2010 as $109B in 2010 dollars. Not cheap, but that's the whole program, from 1961 to 1972. --Trovatore (talk) 20:00, 8 February 2016 (UTC)

The shuttle launches cost about $1.2 billion each (also in 2010 dollars) which sounds cheap...but the $109 billion that Apollo cost is a bit harder to adjust for number of launches because although there were only a dozen or so Saturn V launches - Apollo did a bunch of Saturn I and Little Joe launches before the moon landings - and of course developed a ton of technology and launch facilities that the Shuttle program later relied upon. The estimate for the money saved by NOT flying Apollo's 18, 19 and 20 amounted to about $500 million per launch (again, 2010 dollars) - but you can't use that to say that Apollo missions cost half what the Shuttle did because the Apollo hardware had already been built - and that some of it was ultimately re-used for Skylab.

This means it's unfair to suggest that Apollo was more expensive than the Shuttle program...or vice versa. There is simply no way to divorce spending on the former from benefits to the latter. SteveBaker (talk) 20:43, 8 February 2016 (UTC)

Can any problem be broken down into easy to understand parts?

Is there any problem that cannot be understood when you break it down to its constituents? Can you treat a big problem as a collection of small chunks of problems? And basically, understand any level of complexity with a little brain/computer? --Scicurious (talk) 14:48, 6 February 2016 (UTC)

So far we haven't been able to understand intelligence just by breaking it down, let alone consciousness. We understand neurons, but that doesn't seem to be enough. More generally, any emergent property seems to require looking at the whole system, as it is somehow literally more than the sum of it's parts.

Then there are things we could theoretically understand, if we could identify all the parts, but there's just too many and they are just too small. For example, accurately predicting the weather a year from today. StuRat (talk) 14:54, 6 February 2016 (UTC)

Firstly, we need to restrict ourselves to problems that can be solved. We know that in mathematics, there are fundamentally unsolvable problems. So let's restrict ourselves to problems that can actually be solved.

The question in the title is "Can any problem be broken down into easy to understand parts?" - but I think there are some small, minimum problems that can't be broken down any further. Ultimately, it starts to get difficult to break down "What is 1+1?" into sub-problems - the answer 'just is'. In mathematics, some things are taken to be "axioms" - and you can't break down an axiom...it just "is". However, when you get down to those smallest constituents, I think that most people should be able to understand them. So, I think the answer to this one is a tentative "Yes"...assuming the problem is at least in principle solveable.

The hard part is in the the next question: "Is there any problem that cannot be understood when you break it down to its constituents?". Imagine what happens in a computer program. The "problem" is inherently broken down into the tiniest steps that even a totally mindless computer can understand - things like addition, multiplication, moving a number from one place to another, testing a number to see if it's zero, jumping to a different place in the program. Those steps are definitely small enough that more or less anyone could understand them individually - no single machine-code instruction that a typical computer can run is beyond the capability of most human beings with a knowledge of basic arithmetic to comprehend.

If your theory is correct - then by examining these microscopic "problems" one by one - I can understand anything that a computer can be programmed to do.

But if someone writes a program to (lets say) play chess - and we give the list of individual machine-code instructions to someone who can't play chess. Would breaking down the program of playing chess well into (literally) a billion tiny addition/move/test/jump steps help you to understand how to play the game at grand-master levels?

In this case, breaking down the problem made it much harder to understand. In order to deduce the rules for playing chess, I don't want the ultimately broken-down version of the problem. I want the high-level description.

So, theoretically - yes, the information is in there - but in practice, definitely not!

SteveBaker (talk) 16:00, 6 February 2016 (UTC)

The theoretical way to make a perfect chess-playing program, by looking at every possible move and response by the opponent, to the end of the game, and selecting whatever move leads to the fewest loss and tie scenarios and most wins, is pretty easy to understand. However, that turns out to be impossible for a program (other than at the endgame), due to too many possibilities to calculate. So then you get more complex programs that are difficult to understand by a human. StuRat (talk) 16:17, 6 February 2016 (UTC)

As phrased, there's no simple answer, and no uncontroversial answer, but I'll give you some refs you might like: Emergent phenomena are basically things that are not simply sums of constituent parts, and Stu is right to bring that up as something that doesn't fit well into your scheme. Nonlinear dynamics in general don't lend themselves to clean decomposition. Divide and conquer only works really well for linear and additive systems/problems. Extremal_principles_in_non-equilibrium_thermodynamics and deterministic chaos are two examples of things that aren't that amenable to solving smaller chunks to get a bigger solution. Kolmogorov_complexity is also fun to think about in this context. Self organization is another good example of the need for some Holism in our inquiry. Here's a nice comic on the topic from SMBC [1]. It's telling that analyze literally means "to cut apart" - it's a very useful method and we've done wonderful things with it. But it is not the only way, and all problems are not tractable via decomposition or deconstruction. So while your questions are a little vague and ill-defined (what is a problem, what is understanding?), that's ok, these questions must necessarily be so. My WP:OR answers to your questions are: "Yes, Often, and No." :) SemanticMantis (talk) 16:19, 6 February 2016 (UTC)

I have a related question. The law of entropy is an "emergent property", but isn't it a consequence of Newton's law of motion? If a high speed particle hits a low speed particle, their speed is going to be distributed evenly, isn't this what causes the 2nd law? — Preceding unsigned comment added by Money is tight (talk • contribs) 00:10, 7 February 2016 (UTC)

In the classical mechanics that existed before Isaac Newton, Momentum is conserved in collisions between particles. Momentum is the product of mass and Velocity. Velocity is a vector quantity posessing a direction as well as a magnitude (while <speed> and <mass> have no direction) so momentum is likewise a vector. In 1687 Newton caused to be published in Principia:

Lex. II.

Mutationem motus proportionalem esse vi motrici impressae, & fieri secundum lineam rectam qua vis illa imprimitur.

This is the second of Newton's laws of motion which essentially expresses conservation of momentum in terms of its time derivative Force and of the time-derivative of velocity which is Acceleration. Today we state that the acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object. AllBestFaith (talk) 15:27, 7 February 2016 (UTC)