61

Physics, Astronomy & Cosmology / Re: Optical illusion in GR diagram?

« on: 11/04/2013 04:28:48 »

If you consider a rhombus. The opposite sides are the same distance apart as they would be for a square of equal sides, however the area is reduced. So while there is the same distance between equivalent points on the lines, there is actually less space between the two lines.

Which I think is what Pincho said, but anything I can do to confuse the issue further... []

62

General Science / Re: Please help settle a bet on fluid density?!

« on: 04/04/2013 04:38:04 »

I'm not a scientist but I'm pretty sure you're right. When the density inside the container is the same as the outside, it's weight cancels out.

Another way of thinking about it is if you have a balloon full of air, it doesn't become heavier in air simply because it is sealed.

I know someone will pick me up on the intracacies of mass and weight and how technically, a balloon full of air DOES weigh more. I think I mean bouyency rather than "weight", but I'm not sure...

63

General Science / Re: Is there any reason for parents to make their children eat crusts?

« on: 03/04/2013 23:55:48 »

Do you wish to encourage waste? Do you wish perfectly good food to be thrown away? Are you in favour of careless consumption? Do you think symbolism and good habits have no place in life?

I understand your concerns and I'm more than happy to tell my kid to eat his crusts because otherwise it's a waste of food. I just get annoyed when I hear people tell kids that there is some sort of nutritional benefit to eating what is essentially just an over-cooked portion of the rest of the bread. Clearly if a kid doesn't want to eat it, it is not "the best part" for them. I wondered if there was any scientific validity to claims that it's important to eat crusts for anything other than they taste great (I'm in agreeance there!) and it's wasteful not to.

64

Physiology & Medicine / Is it possible to completely relax all our muscles?

« on: 03/04/2013 03:21:17 »

I've heard that muscles either contract, or relax but we can only create movement by contracting a muscle. So..
a) Is this correct?
b) If so, what would we look like if all of our muscles were relaxed at the same time?
c) What would happen if someone managed to simultaneously contract all their muscles at the same time? (I have an image of horrible muscle damage due to all the muscles pulling away from eachother).

65

General Science / Is there any reason for parents to make their children eat crusts?

« on: 03/04/2013 03:15:13 »

If we're talking about regular white bread, surely the crust holds no more nutritional value than the rest of the bread. So why make kids eat something that is the same as the rest but a bit chewier and (for some) unpleasant to eat?

I know the crusts give you curly hair, but is that the only reason?  []

66

Physics, Astronomy & Cosmology / Re: How do I launder the fabric of space/time?

« on: 28/03/2013 12:47:58 »

Recent results from Planck suggest that this fabric is a bit older than previously believed...

I hope it doesn't start fraying around the edges..

I can never find the edges. Which makes folding it a challenge.

67

Physics, Astronomy & Cosmology / Re: How do I launder the fabric of space/time?

« on: 27/03/2013 21:39:14 »

I find no matter how delicate the cycle is, I always get those pesky 11 dimensional knots in it. (or is it up to 12 now?) []

68

Just Chat! / Re: Punning is hard(ly) work! Groaning aloud here?

« on: 26/03/2013 21:16:10 »

Do you think we should move on? I think these puns are just about eggsahusted now.

Of course, if you have any more to eggstrapolate, do carry on, I'm easy over here.

Move on?!? Ova my dead body!

ps. demo, where do you poach all your pictures from?

bizerl, omletting you know that you understand how to keep the sunny side up.

I'm sure he poached that from me. Him and his egg. No going back now. Heed the warning shell or I'll scramble the RAF.

You're right. There's nothing new here. I fall opianly into submission. It's too hard. Boiled over into ridiculousness this topic has.

who let Yoda in here?

69

Just Chat! / Re: Punning is hard(ly) work! Groaning aloud here?

« on: 26/03/2013 21:10:30 »

Do you think we should move on? I think these puns are just about eggsahusted now.

Of course, if you have any more to eggstrapolate, do carry on, I'm easy over here.

Move on?!? Ova my dead body!

ps. demo, where do you poach all your pictures from?

70

Physics, Astronomy & Cosmology / Re: How do I launder the fabric of space/time?

« on: 26/03/2013 04:50:49 »

It will shrink if the dryer rotates at close to the speed of light.

When ironing anything made from space-time, you need an iron that removes all mass, including dark matter. Any mass will just cause creasing.

71

Just Chat! / Re: Punning is hard(ly) work! Groaning aloud here?

« on: 20/03/2013 10:11:23 »

I was going to post a picture of me in an omelette mask, but I thought I'd just end up with egg on my face.

I bumped into a chick from Kentucky named Dixie who was a delight. She was a small fry so I scrambled to take her under my wing. Hey, she egged me on.

Glad that's over. Easy mistake to make!

72

Geology, Palaeontology & Archaeology / Re: Most Utopian Society In Your Opinion In The Following Specifications

« on: 18/03/2013 23:54:36 »

I'll kick in another two cents here (actually, five cents. We don't have a two cent coin in Australia any more).

I've often thought that a lot of issues could be solved if people lived a lot longer, say 500 years. If people could personally experience large scale changes, it would change our thinking and we'd be more prepared to make changes that might be short-term detrimental, in order to ensure the long-term benefits.

These espers are far from not conscious of their environment, they have clean and sustainable means of energy.  They, however, do not care much about diplomacy and other races.

I have to wonder why a society that seems so highly advanced and "utopian" in itself, does not see the value in bestowing its way of life on others. A key aspect to this sort of society getting to where it did is selflessness. If a society has acheived selflessness, why are they wanting to invade others?

Perhaps the stereotypical "utopia" that we know is a sham (a dictatorship for instance) might serve your purposes better.

73

Marine Science / Does anything eat whale sharks?

« on: 18/03/2013 05:13:24 »

This came from my 5 year old son. I know there are bigger beasts in the ocean, but would they bother with a whale shark?

74

Physics, Astronomy & Cosmology / What comes first? The comet or the tail?

« on: 18/03/2013 01:06:54 »

I'm led to believe that the comet's tail is caused by the solar wind heating the surface and turning the ice into vapour. The pop-culture view is that of a tail streaming out behind a comet as it hurtles through space.

Now, this seems obvious while the comet is heading towards the sun, but what happens when it is on it's way back to the outer solar system? Is the tail still behind the comet's direction of travel, or does it continue to be pointing away from the sun, in which case, the comet would actually be travelling through it's own tail?

75

Physics, Astronomy & Cosmology / Re: Electrons and light speed?

« on: 15/03/2013 01:24:55 »

True EO

But what I'm wondering about there is what properties one could expect from a infinitely dense material. Would sound treat it as some ideal description of mass? meaning no 'vibrations' between its 'property' at all, or would it really 'vibrate' to sound?

If we're talking about crazy infinity stuff, wouldn't an infinitely dense material be a black hole, and therefore any vibrational movement would be damped by gravity? [insert "someone just mentioned black holes on this forum again" smiley]

Also, I always saw sound as a compression wave. If something is infinitely dense, can it be compressed further in order to propogate an oscillating sound wave?

76

General Science / Re: What can you mix with vinegar to create a home made cleaning paste?

« on: 14/03/2013 22:35:03 »

It's funny. I actually find that making a paste out of water and bicarb soda works really well for cleaning the grout between tiles.

77

Question of the Week / Re: QotW - 13.03.14 - Are we the only species which practises dental care?

« on: 14/03/2013 22:24:33 »

We had a dog with bad teeth at one stage. The vet told us to feed her raw chicken bones as the act of chewing and crunching the hard(ish) bones, helped keep the teeth clean.

I'm not sure how herbivores would manage but I'd imagine the occasional chew on a piece of bark might help keep the plaque at bay.

78

Physics, Astronomy & Cosmology / Re: Electrons and light speed?

« on: 14/03/2013 04:59:32 »

When a voltage is applied to something, is there any one particular electron that travels from one terminal to another? I had a (totally unfounded) idea that the effect was more like Newton's cradle where the electrons jumped between the copper (or in this case, silver) atoms.

If we were watching this rod shoot past on Earth and could somehow "see" the electrons "flowing" (in whatever way they flowed) through the rod, it would seem to flow much slower through the rod due to time dilation. The same way that someone running really fast across the top of the rod would seem to be running in slow motion.

If we were travelling on the rod, or at the same speed next to the rod, and we were watching the electrons, they would move just as fast as electrons should move, however the rod would also be at rest in this frame, so it is still slower than c.

I think.

In terms of sound, that's just stuff banging into eachother back and forth. The reason it doesn't propogate through space is there is not enough for it to bang into something else. The reason we can't "hear" a supernova is because not enough particles are being displaced through space for the compression wave to affect the air molecules next to our eardrum. I suppose the denser the material, the easier it is for particles to interact and the compression waves to propogate.

I have heard (on this forum) of something called Cherenkov Radiation which is when something travels faster than light through a medium. So I suppose it is possible for sound to travel faster than light in certain situations, just not in a vacuum.

79

Physics, Astronomy & Cosmology / How is an absolute reference for GPS maintained?

« on: 13/03/2013 23:37:30 »

After skimming through a slightly related post, I find myself wondering how GPS satellites (is that a tautology?) know where the lines of lattitude and longitude are. It seems possible for the equator to be the most stable baseline, but how is that measured? And what about lines of longitude? If there is a slow but measureable shifting of all landmassess, how can we establish a permanent reference point?

80

Geology, Palaeontology & Archaeology / Re: Most Utopian Society In Your Opinion In The Following Specifications

« on: 08/03/2013 04:54:32 »

I've always thought that a sufficiently advanced society would operate without a government or politics and the interactions within would be governed by each members knowledge of what is required for the greater good.

You could look at something like Ursula Le Guin's "The Dispossessed" for an example of such a society.

Another idea was explored by Frank Herbert in "God Emperor of Dune" where an entire galaxy was kept in line by a single (man? worm?) who had altered himself to live for thousands of years in order to conduct his "enforced peace".