At our honourable host D. Allan's suggestion, I'm going to kick in a little science each day (though readers of my blog will know I don't make it every single day). I've called it 'factoids' - which are basically facts separated from all their context - but in fact I'll try to give them enough context to make them meaningful and interesting. Others are very welcome to comment, or to contribute interesting factoids of their own... but I will be fact checking!

This should be fun!

We are outnumbered 10-fold in our own bodies by microorganisms. We have about 10^13 cells in our bodies, and about 10^14 bacteria, viruses and other microorganisms in and on us.

(Can't post a link or reference for this one because I heard it from a biologist at my university in conversation)

My oh my! Each one of us is a walking bio-environment! How does our personal populations compare with the population of our planet? Can you help this math-dunce? <:)

The (human) population of the planet is on the order of 10^10, so our personal bugatariums are 10,000 times more populous.

I think I have 10^5 bacteria congregating in my ears right now, making them hurt!

Ack, not good

/me sends Gail 10^6 virtual hugs

:)

Staying on the buggy tip for a while:

Scientists have only identified about 4,000 of the estimated 400,000 species of viruses in the world.

http://www.all-species.org/wsj_012202.html (from that well known scientific journal... the one from Wall Street)

(for those moments when we think most of the science is already done)

Insects rule : 950,000 identified out of 8 million estimated species. (same source)

I wonder how they compare in their populations: more viruses or more insects?

Hmm, yeah, not sure... but if say 1/10 of them there bugs on our bodies are viruses, then that's 10^13 per person, times 10^10 persons for 10^23 viruses, just in people, not in soil, water, animals and plants.

My guess is there are more virii, 'cos they're much tinier, and I couldn't find anything definitive on their relative populations.

That seems reasonable. They are our most formidable competitors, outside of our fellow humanoids!

Fleas can jump 130 times higher than their own height. In human terms this is equal to a 6ft. person jumping 780 ft. into the air.

Not a direct link to this factoid (which is disputed - some say 80 times their height, which would still translate to a pretty darn impressive 480 ft), but fun anyway: http://www.ftexploring.com/lifetech/flsbws1.html

It has a lot to do with the 'square-cube law'. Strength goes up as the square of size but mass goes up (and down) as the cube. I think I may have talked about this before with the ant, mouse, cat, person, horse and elephant falling down a mineshaft...

Interesting. For any type of object or matter?

Basically, yes, if you simply magnify/shrink a shape, keeping its proportions, and keeping well away from the atomic scale or continental scale sizes...

It is a bit trickier than that for biological material because muscle because there are limits to how large or small cells can be - so a mouse has similar size cells to a person.

Muscle strength is basically proportional to the cross-sectional area of the muscle. Making the muscle longer does not make it any stronger - it just increases the distance over which it can exert the same strength.

In fact individual muscle cells can't vary the strength of their pull - they are either pulling or they are not. We control how hard we pull by using more or less cells, not by having each cell pull less.

Weight is proportional to volume.

This is why you can't just scale an animal up and down. A 7ft+ human has problems caused by their cross-section not being adequate for the amount of material above that point.

/Bevin

Absolutely fascinating! I did wonder about some of the issues Bevin raised, in terms of mass/volume ratios for living organisms, depending on the type of body tissue involved. I did not know that muscle exertion is a function of the number of cells! Great info! Thanks, Bevin.

Not a factoid today but a link... One of my friends and former colleagues in Canada, Frank Jenkins, set me this (note that there's a link to a podcast online, so you don't have to live in Canada (or listen on Sabbath) to listen):

This week on Quirks & Quarks: (CBC Radio 740 at 12:05 PM)
http://www.cbc.ca/quirks/podcast.html

It's the Great Aussie/Canuck Science Adventure.

The moose goes walkabout with the wombat, and the beaver goes camping with the kangaroo, as Bob McDonald goes Down Under for the Great Aussie/Canuck Science Adventure.

Quirks & Quarks, Canada's national science program, and The Science Show, Australia's equivalent program on ABC Radio National, are joining forces for a unique exploration of
science, north and south. And here's the kicker: both programs first went on the air at virtually the same time in 1975.
And both are now broadcast on Saturdays at noon.

In the first program, the host of The Science Show, Robyn Williams, introduces Bob to leading Australian researchers. And in the second program, Bob introduces Robyn to Canadian scientists. And both programs get to hear both of the hosts doing the interviews.

April 21: Bob interviews the Australians:

Bob learns about farming and eating kangaroos; saving the Tasmanian Devil from extinction; discovering the fossils of marsupial lions; and avoiding the deadly sting of the Irukandji jellyfish.

All this and more on Quirks & Quarks, with host Bob McDonald, Saturday right after the noon news on Radio One, or anytime on our web page at cbc.ca/quirks.

Fun science fact(oid)s tend to be from biology most often... but chemistry and physics are my beloved fields of science, so I wanted to try to include some from those fields too.

Here's a fairly simple one:

A pendulum one metre long has a 'period' for its swing (the time it takes to swing out to the other end and back to where it started) of 2.0050 seconds.

Many people thought the metre should have been defined as the length of pendulum that produces a period of exactly 2.0000 seconds, because that would have made it simple to measure one metre anywhere in the world if you had a watch and a piece of string.

But as it is, if you have a ruler, a piece of string and a weight, you can make a pretty accurate 'counting clock'.

(A metre is pretty close to 39 inches)

The chemical element Gallium has a melting point of just under 30 C (86 F), which means that it melts in your hand (unlike M & Ms - and don't put it in your mouth!)

Gallium is a semiconductor material, used to make some computer parts.

Bentor, Yinon. Chemical Element.com - Gallium. Apr. 23, 2007 <http://www.chemicalelements.com/elements/ga.html>

Okay, then HOW can it be used in a computer, in which the internal temperature will easily go above 100 degrees F, particularly laptops with the tiny fans?

Dave

Great question (someone's thinking!) The form used in semiconductors is actually a compound of gallium, gallium arsenide, so gallium combined with arsenic. This compound has a melting point of 1238 C, so it's completely safe even in hot computers.

http://en.wikipedia.org/wiki/Gallium_arsenide

Unfortunately the period of a pendulum's swing depends on

(a) air density
(b) distance from the center of the earth

(b) is measurable - because the earth has a bulge at the equator, so pendulums swing measurably slower there...

Then, of course, there is the problem of getting a reliable clock that does not use a pendulum - easy today, but not 200 years ago...

/Bevin

I suspect that both (a) and (b) would have effects smaller than the .005 in the 2.005, so yeah, you wouldn't use a pendulum clock to time the 100 m race at the Olympics, but for timing an egg or taking a pulse it'd work fine. Incidentally, you've probably noticed that clock pendulums tend to be very thin in the plane in which they swing, presumably as a means of reducing the influence of (a).

Actually I realized there is an age-old reliable-enough clock - the rotation of the earth! So you would adjust the length of the pendulum until it did 24*60*(60/2) swings per day, where day is measured by a star crossing a hair in a telescope....

Of course that means having someone count about 50,000 swings... unless you also invented a counting device...

/Bevin

so it is about 50/12756 = 1/240 difference in radius

so g at one place is (240/240)**2 and the other ((240-1)/240)**2 so the difference is about (2*1*240/240)**2 or (1/120)**2 or about 0.0001 << 0.005

There is another effect also - centrifugal forces - but I suspect without calculation this is even more irrelevant...

A less irrelevant topic may be the shape and density of the pendulum - you would have to agree on that also...

Yeah, the equations for the pendulum require it to have a string of zero mass and a bob that is a point mass, so the denser the better. Lead is a good start, but in a war zone maybe you could pick up some depleted uranium.

This is all very interesting but way beyond me!!

I wish I hadn't skipped out of school so much!

I'm going to assume that they don't feel this elongating in space but what about when they are back on earth. Do they feel themselves shortening? How long does it take to shorten up?

And we can't ignore the 'human sciences':

In the developing world, fertility rates vary in inverse proportion with literacy rates. For example, Afghanistan, with a female literacy rate of only eight percent has a fertility rate of 6.9 per 1,000 population. Thailand, in contrast, has a literacy rate of 88% and a fertility rate of 2.6/1,000.

How do you know this? Have you counted all the stars?

Nevah, nevah, nevah understimate Bravus, Amelia!!!

The key phrase was "known universe"

Indeed. And, that calculation has been made. The boundaries of our universe have been theorized. The most distant observed celestial objects, to date, appear to be near the theoretical limits of this universe.

I didn't count them all, but these guys did: http://edition.cnn.com/2003/TECH/space/07/22/stars.survey/

Mind you, even they say it's possible there are an infinite number.

And while we're on astronomy, here's an exciting find just publicised:

http://www.theage.com.au/articles/2007/04/25/1177459786135.html

It's not an alternative home for humans, because the planet is 5 times as massive as earth, so we'd weigh 5 times as much, and we're not built for that, but it looks as though it has liquid water (or at least the potential for same). Wouldn't it be cool if there were living things there?

An infinite number? They must be exaggerating a little bit. :)

Well, I think they are acknowledging that, although most of our best current models see the universe as closed and expanding and of finite though huge extension, there are other models that see it as of infinite extent. In an infinitely large universe you would presumably have an infinite number of stars.

Mind you, 70 sextillion is not infinity, but you can almost see it from there. ;)

But my point was that we can get lost in how huge the universe is, and not realise that the glass of water in our hand contains 100 times as many particles as the number of stars! The simple stuff is amazing too! It's all amazing!

Here's my rough calculation:

70 sextillion stars is 7 x 10²².

One mole of water contains 6.02 x 10²³ water molecules, weighs 18 grams and fills 18 mls, because water has a density of 1 gram/ml. A cup of water is about 200 ml, or about 11 moles. 11 x 6.02 x 10²³ = 6.7 x 10²⁴... which is roughly 100 times 7 x10²².

I've really goofed. I asked Bevin to host a thread on Astronomy and then here I asked Bravus a question about the stars! Sorry Bevin. And if that was not a big enough goof I also forgot to inform Bravus about the new thread, Stars are God's Fireworks! I'm sorry, Bravus.

I apologize ... to Bevin, Bravus and everybody.

It's just all part of the fun :)

Yeah, no worries at all... and we seem to both be happy commenting on each other's threads anyway. I suspect us geeks are just happy to have someone to talk to about the awesomeness of creation.

Thanks, guys! BTW wasn't that an awesome movie clip from Nasa that Bevin linked to for us? I just put it on repeat and watched and watched!

No apology needed about the cross-fertilization!

Why don't these alligators and crocodiles get frost-bite?

/Bevin

Dunno - coldbloodedness?

The space shuttle has three rocket engines in the back, but there's absolutely no room inside for all the fuel it needs to launch itself up into space. All of that fuel is stored outside the shuttle, in the big brown cylinder, called the external tank.

The tank containing all the rocket fuel weighs seven times more than the space shuttle itself! That's a lot of really heavy fuel, and the space shuttle engines aren't quite strong enough to push the combined weight of the shuttle and the big bloated external tank up off the ground.

That's what the two long white solid rocket boosters strapped onto the sides of the external tank are for. They lift the tank! Fortunately, it was not necessary to strap an infinite series of smaller and smaller rockets to the sides of the solid rocket boosters.

From: http://www.coolsciencefacts.com/

Cool related factoid

The solid fuel motors have a hole right up the middle, and they burn the entire length of this hole, not just at the bottom end.

The fuel itself provides the protection for the surrounding casing during most of the burn...

By changing the shape of the hole, you can change the thrust-over-time curve of the burning rocket. A cylinder has the least surface area initially and, as it burns wider, the thrust grows.

A star-shaped hole is often used - you can get almost constant thrust out of that...

http://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster



/Bevin

That is cool - it seems in some ways a low-tech solution to a high-tech problem, in a good way.

This is the exact same fuel that hobby rocketeers use and they make it at home!

What I would like to know, is there ever a future possiblity of some type of fuel that would allow space flight without HUGE external rocket boosters?

It would have to be a fuel that packed even *more* energy into a smaller space, and I think we might already be approaching some of the limits of chemistry and bonding with the fuels we're already using. The other consideration is the exhaust: the shuttle uses oxygen and hydrogen, which means those big plumes of white exhaust are all just water vapor. (The solid boosters are something else, and presumably have some exhaust impact on the environment.)

The really cool future possibility is the 'space elevator'. ;)

Years ago when the concept first hit the news, I saw an animation of how it would work. It was a cable with a platform that road up and down and took hours of travel. Of course today the looks of the concept have changed greatly. But one blogger posed this question: What musak do you play in an elevator where the trip covers 62,000 miles? ROFL

Can we go back to the fertility rates? Could the higher fertility rate in the less educated countries make up for the lack of knowledge which would cause there to be a higher infant-mortality rate?

I'm not sure how those fertility rates are calculated, Dottie, and whether they are at birth or require survival to age 1 or so. If it's birth then yes, there would be some degree of that, but the populations are still growing over all. I don't usually have any agenda in posting these science bites, but one reason I'd remembered that one is that I think anyone who is concerned about over-population on this planet should be concentrating hard on access to education for women, since that's the thing that has been repeatedly shown to reduce birth rates.

Some spiders' feet are covered with tiny hairs. These hairs give spiders the strength to hold 170 times their body weight before coming unstuck. That would be the same as Spider-Man carrying 170 people from danger while clinging to a building with his fingers and toes.

Scientists hope that they can use the secret of spiders' stickiness to make better sticky notes, gloves for soccer goalies, and even boots for astronauts.

http://news.nationalgeographic.com/kids/2004/07/spiderman.html