Ask MetaFilter questions in the science & nature category

Where can I go stargazing in the Boston area?

Plutor — Mon, 09 Nov 2009 09:03:09 -0800

Where can I go stargazing in the Boston area? I want to take my wife to see the Leonids next week. Where can we go in the area that's as dark as possible but is convenient, comfortable, and legal?

Never had a nightmare

Anonymous — Sun, 08 Nov 2009 18:25:29 -0800

I've never had a nightmare. Why? Is this normal? I can't fully account for when I was a small child, but in recent memory I cannot remember ever having had a nightmare, or even a truly disturbing dream. I've had exceptionally vivid dreams as well as the usual anxiety dreams of being naked or falling on rare occassions, but never anything close to nightmarish. Amongst my friends and family I can't find anyone else who has never had a nightmare. It feels weird.

Googling "never had a nightmare" shows I am not alone, I just wonder if there might be a cause, or an article or some sort of insight into this. I've had a normal-to-difficult life including problems with depression and anxiety and a fair share of waking problems, I can't think why I might be immune to having nightmares. Is there a cause, or am I just lucky? Any tips for inducing a nightmare? I guess I am coming from a view of nightmares being an accepted part of everyone's life, perhaps they aren't?

FWIW I'm not on any medications or diet, I drink moderately, no drugs, exercise daily, eat healthily. Slept in all sorts of environments home and abroad and no other sleep issues. Mid 30's.

Breathing holes from a giant undersea Cthulhu

shammack — Sat, 07 Nov 2009 09:09:58 -0800

What is this thing that we found on the beach? We saw several of these things in the sand during low tide in Panacea, Florida. My wife poked at one and it fell apart. What is it?

Germs: pretty much everywhere

Busoni — Sat, 07 Nov 2009 05:37:21 -0800

Epidemiology-and-Germ-Theory-Filter: are bacteria, viruses, fungi, etc. that cause common conditions (such as warts, conjunctivitis, and ringworm, for instance) pretty much everywhere (already)? The relevant literature suggests that they are fairly contagious, and spread by contact. But while one can take precautions towards limiting contagion, doesn't it seem that given the prevalence of these diseases and the lack of precautions most people take, that the agents that cause these diseases must already be pretty ubiquitous, and that the only reason that not everyone has warts and pink eye is that people's immune systems are functioning properly?

In other words, am I right in saying that: although you probably want to avoid wrestling nude in the shower room at the Y, and farting bare-assed on people's pillows, people usually get warts and pink eye not because they failed to take these precautions, but because the germs that cause them are already pretty much everywhere, and happened to catch these people on a bad day, immunologically speaking?

What's not working yet in the Theory of Natural Selection?

dpcoffin — Fri, 06 Nov 2009 17:13:53 -0800

When current/recent SCIENCE challenges Darwin, what does it say? I'm a layman interested to hear what not-Creationist, not-ID, not-paranormal challengers (or boundary-pushers) to natural selection might be exploring these days, explained for general readers… "13 Things that Don't Make Sense: The Darwin Version!" would be perfect. Failing that, are there any book/lecture summaries, web-sites, authors, etc. out there trying to let the person on the street know what some or any serious-science folk might feel is resisting explanation by, or still not quite fitting into, natural selection as the sole mechanism for the shaping of life forms and the building of symbiotic relationships?

There appear to be plenty of "How it all works" writings; are there any "Here's what doesn't quite work yet" books, chapters, footnotes, etc., either from within the ranks, or from other mainstream scientific disciplines?

Or perhaps: What are the still-unsolved, bleeding-edge aspects of the theory?

Or even: How has the theory had to stretch lately to keep pace with new findings?

Thanks!

Business leaders who made great strides for the environment?

carrolldamian — Fri, 06 Nov 2009 12:05:00 -0800

I am trying to come up with names of prominent business leaders through history who took major steps forward on environmental stewardship/protection. These should be industry titans who went against the grain in emphasizing environmentalism as part of their business model. Extra points if the person saw unexpected or un-predicted success as a result of their decision to "go green."

What is the chane of this event happening?

jackypaper — Fri, 06 Nov 2009 09:43:10 -0800

I have an event that has a 75% chance of happening. If I run the trial seven times, what is the probability of the event happening at least once? And what's the math behind it?

Interpretation of cross-correlation and cross-covariance plots

noztran — Fri, 06 Nov 2009 06:56:44 -0800

How to interpret certain features? I am looking for some help regarding interpretation of both cross-correlation and cross-covariance plots.

Namely, I have been struggling with these features:

* sudden negative spike immediately followed by positive spike
* broad ('smeared') bulge
* oscillation of the plot (i.e. the trace somewhat resembling a sine)
* ondulation of the trace (think of it as if you were writing u's continuously)

I have been going through google over and over again, but to no avail. Are there any good sources/books/etc. that deal with actual interpretation of cross-correlation and cross-covariance plots?

BONUS question: to what extent can cross-correlation and cross-covariance be treated as a representation of impulse response function?

Any thoughts will be appreciated.

Do I have a body language speech impediment?

bartleby — Thu, 05 Nov 2009 14:35:04 -0800

I've been watching a lot of Lie to Me, and it's making me think that I've got an answer to why I get misinterpreted a lot; is it possible that my microexpressions are "wrong"? So there's this US TV show called Lie to Me, which is based on the study of microexpressions and the work of Paul Ekman and others.

The premise is a lot like reading "tells" when playing poker, and goes like this, simplified:
1) when you smell something bad, you make a "stink-face"
2) pretty much everyone everywhere makes the same "stink-face"
3) even if you're trying to be polite or conceal your reaction, the mind-body(face) connection is so strong that unless you're very highly skilled, the "stink-face" is going to flash across your face as a microexpression
4) some people can consciously and clearly read these microexpressions in the faces of others, making them natural lie detectors; but most people only register them subconsciously. Even the subconscious registering of them is how we get clues to the emotional or mental states of others, to the point that people who can't read faces at all usually get diagnosed with a disorder like autism or Asperger's.

Now I've always had a problem going in the other direction; people seem to take subconscious cues from me that aren't accurate. They'll think I'm lying when I'm telling the truth, or that I'm upset about something when I have no feelings either way about it.

Could it be possible that my microexpressions are somehow off-kilter? Do I have a body language speech impediment?

What's more important, a magnet's surface area or thickness?

howling fantods — Thu, 05 Nov 2009 11:27:53 -0800

What contributes more to the attractive force between a magnet and a thin piece of metal - the magnet's surface area, or its thickness? Suppose I have thin piece of metal and a neodymium disc magnet. With everything else being equal, will a thin magnet with a large surface area provide a stronger pulling force than a thicker magnet with a smaller diameter? In either case, the piece of metal is no thicker than the magnet itself.

why are some clouds black while others are white

zeoslap — Thu, 05 Nov 2009 09:14:56 -0800

Why are some clouds black while others are white? So looking out of my window I can see storm clouds coming in and they are black (well dark grey) even the wispy bits at the top of them while other clouds higher up are white.

Do the dark clouds look that way because of water content?

How would I pick which equation to use?

lpctstr; — Wed, 04 Nov 2009 22:49:49 -0800

I want to determine the difference between distributions. When would I use kl-divergence and when would I use rmse? It seems like both equations reduce deviation to a single number, but couldn't find a comparison between them.

A mystery in the window of a pickup truck

longsleeves — Wed, 04 Nov 2009 16:20:49 -0800

What could be causing an image of Jesus to appear in this man's truck window? What sort of treatment or coating could cause an image to reccur like this handsome visage of Jesus is reported to?

Laboratory of iPhonology

roofus — Wed, 04 Nov 2009 13:10:37 -0800

Any recommendations for iPhone apps or Web apps that will be useful in a basic science lab. I would like suggestions for handy apps for:

- running multiple timers
- anything that will expand my understanding of modern molecular biology
- literature searching (particularly genetics)
- general productivity

I am already au fait with Things, Evernote, Papers, and iTunes U

Rates of success?

rollick — Wed, 04 Nov 2009 09:46:36 -0800

Statistics question: is it possible to test sets of cumulative data for significant differences in rate? I have three cumulative percentage graphs, measuring the germination rates of three different seed types. Is there a way to compare them and see if there are any statistically significant differences?

The seed types were planted in triplicate, on three dishes each (nine overall). Every day for the past few weeks I've observed how many seeds on each dish have begun germinating -- so for an individual dish I would have " Day 1: 0 ... Day 7: 14 ... Day 14: 29" etc, with each day's score a cumulative total. (There are 100 seeds on each dish, so it works as a percentage rate as well)

In Excel, I've graphed the average germination rates of the replicates, for a graph that resembles this one. (with three lines plotted, and x-axis = time in days, y-axis = percent germinated).

So is there a way to compare these different rates statistically? I can use Excel, Minitab, SPSS, and R.

You are not my quantum mechanic

Kid Charlemagne — Wed, 04 Nov 2009 07:57:42 -0800

I'm looking for something like Feynman's explanation for how a difraction grating works only for the absorbance of a colored chemical in solution. In biochemistry there is a technique where one measures protein concentration by looking at how much UV light the protein absorbs. Unfortunatly this technique doesn't see agregates (big blobs of amorphous protein) the same way it sees properly folded protein in solution.

The traditional explanation has to do with things being in the shadow of other things. But recently I've heard people making arguments about the wavelength of the light and how big the particles are. I can tell that both sides are way off base in terms of modern physics.

Can anyone point me at something that would explain this phenomenon the way it really happens, but with out too much (any) tensor calculus?

Magratheans, anyone?

The otter lady — Mon, 02 Nov 2009 18:06:41 -0800

How do I discover what day/night and seasonal cycles are like on a hypothetical unusual planet? I would like to be able to find out how, given, say, an earth-sized globe, with, say, two suns, and four moons, and a retrograde orbit.... or, wait, suppose my world is flat, like Terry Pratchett's Discworld; how fast does a miniature sun have to orbit to give the impression of normal daytime? What if the world is a cube; what does sunrise look like? What if the world is like a ball where the top half spins clockwise and the bottom half spins in the opposite direction; how do days and nights appear? What about if our Earth spun around the east-west axis instead of around the North/south one? What about a Dyson sphere, or a ringworld like the one in Halo? Spinning or stable? How long is a day, a year, a season? What's the climate like? Etc.!!

I'm not so much interested in the physics of how such a thing could exist, as how it would appear to people living on it. Obviously a lot of magic or fudging could be involved, but if there's something cool like "night only comes once every hundred years" or "a day is about an hour long, so the sun seems to whip across the sky like a comet" I would like to know it.

Is there a computer simulation program that could maybe help with this, or perhaps a well-written book that could make some of this understandable to the layman? Ideally I would have a pet mad scientist whom I could say, “Design me a planet that's shaped like a donut and tell me how it works!”... any volunteers?

How can you see what I saw?

history is a weapon — Sun, 01 Nov 2009 17:40:32 -0800

In 35 mm terms, how wide angle are our eyes? Understanding that we have our main vision, what we're actually focusing on, and our peripheral vision, what we can sort of see, what're the answers to this? For example, can we focus the equivalent of a 22mm lens on a fullframe 35mm? I understand that our eyes and brain are much more complex than a lens; I'm more interested in the physical frame in terms of what lens would most closely replicate natural vision.

Roaches in buildings

emilyd22222 — Sun, 01 Nov 2009 15:35:42 -0800

Are there roaches in every U.S. building? I distinctly remember hearing from a credible source (may have been the New Yorker) that every building in the U.S. has roaches in it. This was probably a qualified statement, like "every large building" or "every building over 10 years old" or something. Now I'm trying to settle an argument with a friend, who claims that there aren't roaches in the 8-floor, 30 year old university building in which we work. Help me, Hive Mind! Is there any data about the extent of roach infestation?

Incest taboos: do animals have them?

thisperon — Sun, 01 Nov 2009 02:07:47 -0800

How common is incest in the animal kingdom? Do lion cubs of the opposite sex mate with one another? Will a mother bird mate with her son? Do related domestic animals tend to mate with one another without any encouragement from humans?

What might one see hiking in the woods at night that looks like glowing eyes?

weston — Sat, 31 Oct 2009 18:31:52 -0800

What might one see hiking in the woods at night that looks like glowing eyes? A couple of years ago I was part of a hiking party of three to some hot springs in Utah (Diamond Fork). We started late and took a trail we didn't know well. Two hours into the hike, not only were we not finding our destination, but the woods were getting denser and darker, blocking the moonlight, and we were getting progressively more spooked. About 1 am, we stopped to discuss turning around and giving up. This was when a random flashlight probe into the nearby trees revealed... two spark-ish points light that looked for all the world like eyes.

We held the beam there for a moment and asked amongst ourselves to see if everybody thought the same thing. Each of us confirmed this.

Now, at this point, we were pretty much thinking/hoping it might be reflections of dew, or maybe some woodland creature like an owl or a deer. When we moved the flashlight beam away for a bit to test the reflection theory... the points of light remained.

We moved the beam back. The points were still there. We stared for a bit and again asked each other for visual confirmation, getting increasingly nervous. Then they were gone.

We decided to get back as quickly as possible.

Any ideas what we might have seen?

(While I appreciate the fact that the human mind has a large capacity to play tricks on itself, I'm particularly interested in other explanations.)

Countdown

Blazecock Pileon — Fri, 30 Oct 2009 13:31:34 -0800

Is there an enumeration of complete chess games? Has anyone made an accurate (ideally, "closed form") count of possible chess games?

I found an older article via Google that does a very rough guess-timate of how many complete chess games are possible.

I'm curious if anyone has since tried to count all possible games, given standard FIDE rules, played to completion. Presumably, for example, it is not exponential because some moves will result in an end state ("checkmate" or "stalemate") faster than other moves.

Please do not offer speculation about the answer
Please do not link to Google search results (unless you have found something that answers the question as specifically framed)
Thanks!

Website to sort and display different mountain heights?

seasparrow — Fri, 30 Oct 2009 05:56:36 -0800

Is there a website that would show the world sorted by elevation? I recently enjoyed reading Plague Year, a post-apocalyptic thriller. The main conceit of this science-fiction novel is that a nanotechnology plague that kills any warm blooded animal (including humans), but the disease self-destructs at altitudes above 10,000 feet. How much territory would this be across the whole planet? I liked the book. It isn't great literature, but the author, Jeff Carlson, thinks through the ramifications of a world where most mammals are now extinct and a tiny fragment of humanity clings to a few frozen mountain-tops. Carlson also doesn't shy away or sugar-coat the realities of such a situation. He also doesn't make it easy for his characters, unlike other authors in the post-apocalyptic genre. (Yes, I'm pointing at you, S.M. Stirling.) Some of the protagonists feel guilty about the cannibalism they had to resort to in order to survive, but at least they are alive, unlike 99.9% of the human race.

So, like I said, a fun read that got me thinking. My real question for the Hive Mind is-- in all the great variety of the internet, is there some sort of geographical website that would allow me to view the world through the filter of all elevations above 10,000 feet?

Which sparks another question: Have you seen the maps that occasionally appear showing what the world would look like if global warming caused the sea levels to rise 50 or 100 feet? Is there a website that will let you do that as well? Maybe even set your own parameters on how much you want the water levels to rise or fall, and then generate a map for you?

Does anyone work in the field? Isn't is called Geographical Information Systems? It sounds fascinating. I think I might enjoy working a GIS job eventually. Questions like these linger in my mind, so much so that I'm willing to spend my one-a-week currency of an AskMe question to see what the sophisticated and cosmopolitcal Mefite community has to say about it.

Thanks for your help, and I hope I'm not the only weirdo who thinks about these things!

How can I calculate side force on my car?

krisak — Thu, 29 Oct 2009 20:22:57 -0800

Physics question - involving cars, air, momentum, force, etc... Basically - how can I calculate the side force from a crosswind on my car at any given speed? (Yes, I googled as much as I could and couldn't come up with a formula for this.)

First off, I drive a 2001 Mazda Miata. 155.7 inches long by 48.4 inches tall. Considering the shape of the car, let's assume 155x35 inches as a side profile.

I'm not sure if the front dimensions are important, but I can measure the front end if necessary. For the sake of the math, I think we should disregard the front end of the car - I don't know what the drag ratio and force necessary to push through the air are on this car.

I guess my real question is how do I come up with a figure for how much force a cross wind applies to my car? And, at any given speed, how does that translate into lateral acceleration? (I understand I may be asking the wrong question here.) I know that a 10 mph crosswind will have a different effect when the car is traveling at 5 mph versus 50 mph.

This question comes out of the fact that while driving to work this morning I almost couldn't change lanes due to an 85 mph forward speed coupled with a 50 mph cross wind. I know that at a 10 mph forward speed the effect of that side wind would be lessened, I just want to understand the math behind why.

I apologize in advance for being unable to phrase this question properly. :) Perhaps part of this question is meant to ask "how do I phrase this properly such that I can get a solution to the question?"

Bicycles & physics

bluelight — Thu, 29 Oct 2009 06:49:13 -0800

bicyclefilter: Are there any sites or books that break down the science of a bicycle? I want to understand how a bicycle works. I have a pretty good bicycle mechanics book (Zinn and the art of mountain bike maintenance) but I want to gain a deeper understanding.

I don't have much of a physics background, but I want to understand things such as how/why the rear derailer pulley system works and how mechanical advantage and the braking system are related.

The Sheldon Brown website covers this a little bit (he does discuss MA) but I'm still looking for more sources.

Thanks!