Wikipedia:Reference desk archive/Science/2006 September 14

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September 14[edit]

The Rooster of Bankiva?[edit]

Someone who looks like they have ESL has added a bunch of stuff to the Crest (bird) article. At the moment, I'm trying to read through it, try to get the gist of what the anon was trying to say and see if any of it is salvagable. There is a reference in the article to Rooster of Bankiva. Anyone know what the heck that is? Cheers. --Kurt Shaped Box 00:31, 14 September 2006 (UTC)

Gallus gallus bankiva is one of the Red Junglefowl species, believed to be the ancestors of the domestic chicken.---Sluzzelin 00:45, 14 September 2006 (UTC)

Northern Hemishere[edit]

The Northern Hemisphere is located between ______ and the _______? I think the second blank in the equator but I am not sure what the first blank may be.

This sounds like a homework question dude, so I'm just gonna give you a hint. Think Santa Claus --AstoVidatu 02:53, 14 September 2006 (UTC)
The original Santa Claus came from present day Turkey, and the modern version comes from Lapland, so that was a lousy hint. :) DirkvdM 09:59, 14 September 2006 (UTC)
Actually that's wrong, it isn't like at the north pole you aren't in the Northern Hemispehre anymore. Everything north of the equator would be the right answer. — [Mac Davis](talk) (New! SUPERDESK|Help me improve)03:52, 14 September 2006 (UTC)
The Northern Hemisphere is located between the Southern Hemisphere and the Very Northern Hemisphere. Peter Grey 04:13, 14 September 2006 (UTC)
How about "The Northern Hemisphere is located between the Southern Hemisphere and Polaris"? -- Deville (Talk) 04:23, 14 September 2006 (UTC)
The zeroeth latitude and Polaris. -- Fuzzyeric 04:27, 14 September 2006 (UTC)
mexico and canada? you'd think it sometimes. Xcomradex 05:33, 14 September 2006 (UTC)
Bwfsssahahaha! —Bromskloss 07:50, 14 September 2006 (UTC)
A gull sitting right on top of a pole at the north pole? If it's a homework question it's a pretty dumb one.--Shantavira 08:18, 14 September 2006 (UTC)
Yeah, USians also seem to think that the Western hemisphere equals America, while the name is an obvious hint that it refers to a whole hemisphere. DirkvdM 09:59, 14 September 2006 (UTC)
If you are complaining about far Western Europe and Africa, then you're right, we lump those in with the Eastern Hemisphere, since they are geologically, physically, politically, socially, and economically tied to the Eastern Hemisphere. The line really should have been drawn between Iceland and Greenland, that would have been far more logical. StuRat 16:40, 14 September 2006 (UTC)
Is that possible without bending the line? JackofOz 00:48, 16 September 2006 (UTC)
You might have to put some zig-zags in it, like the International Date Line, or you could cut Greenland in half (since Greenland has such a low population, you wouldn't affect many people if you did). StuRat 05:57, 22 September 2006 (UTC)
THe northern hemisphere is located between the equator and the northern edge of the universe--Light current 17:20, 14 September 2006 (UTC)
The equator and the next turtle's feet? -- Plutortalkcontribs 19:00, 14 September 2006 (UTC)
So where is the East Pole located? -- 8:44 15 September 2006 (PST)
At the intersection of the prime meridian and the equator. --Bowlhover 05:28, 16 September 2006 (UTC)

Speed Of Light[edit]

I am seriously confused on some things on the topic of craft moving near the speed of light. I would like to know first does time slow down for the passengers in the craft as they approce light speed? Second If so would they barely age on lets say a fifty year mission traveling at about 90percent the speed of light compaared to the same fifty years on earth which people aged fifty years? Once again I'm seriously confused thanks for all the help. 04:32, 14 September 2006 (UTC)

Sounds about right to me... am I missing something? Why do you doubt your own answers? If you haven't already, see time dilation (and maybe twin paradox as well). --Allen 04:45, 14 September 2006 (UTC)
Assuming constant motion, the passengers would not notice anything different in the spacecraft. If they looked out of the window however, they would see everything aging more slowley. The twins paradox is very confusing for people who only understand special relativity. This confusion arises from there being no preferred inertial frame of reference (it is not possible for an observer to tell if he is moving or or everything else is moving). This, however, only applies to constant motion frames of reference. It is possible for an observer to tell if he/she is accelerating (changing their velocity - yes this could mean slowing down). In the twins paradox, the twin on the spaceship will be younger on the return because he/she will have accelerated.
If one has accelerated from the other, why not has the other accelerated away from the one? (as measured by determining the red shift of their beams of light pointing at each other?) 8-)--Light current 02:50, 15 September 2006 (UTC)
One will experience a force (Newton's second law: F = dp/dt). The other will not. Even if you're trapped in an opaque box, you can tell whether you've been accelerated. -- Fuzzyeric 03:57, 15 September 2006 (UTC)
OK you can tell whether youre being accelerated or not. How does that age one twin rather than the other. Everything else is reciprocal--Light current 00:58, 16 September 2006 (UTC)
Gravitational time dilation describes the differential time effect for an accelerated twin. As described in introduction to general relativity gravitational acceleration is indistinguishable from any other form of acceleration. (Think about being in the opaque box and trying to tell the diffrence.) So, we have this timline:
  1. Traveling twin experiences a force, after which he knows that his reference frame is moving relative to his initial frame. The stationary twin is unaccelerated and therefore knows that his reference frame is not moving relative to his initial frame.
  2. Traveling twin hurtles through space, his clock running slow relative to his initial frame and (equivalently) the stationary twin. The stationary twin knows that his clock is right (as long as he feels no forces).
  3. Traveling twin has a big acceleration turning around. His clock runs even slower during the acceleration.
  4. Traveling twin returns, with a slow clock.
  5. Traveling twin decelerates, his clock running even slower due to the acceleration.
  6. When traveling twin arrives back, his clock has been running slow the entire time. Stationary twin has experienced no accelerations, so both twins know that the traveling twin's clock was running slower pretty much all the time.
The situation isn't symmetric. One twin has been pressed to the walls of his black box several times and the other has not. This is explained at twin paradox as referenced above. -- Fuzzyeric 02:59, 16 September 2006 (UTC)
So its accn that slows the clock. OK Say the traveller accelerates away at only 1g. The stay home twin also experiences 1 g on earth. How now? Whose time is going slower?--Light current 03:46, 16 September 2006 (UTC)
Is it really that difficult to read the referenced articles? And no, the traveling twin originally experiences > 1 g as he accelerates out of the potential well the stationary twin is stuck in. However, the situation you're tring to describe, where each twin experiences 1 g acceleration continuous is still discriminable because one twin experiences the acceleration in the same direction all the time and the other does not. Really, go read the articles. Right now. Don't delay. -- Fuzzyeric 04:18, 16 September 2006 (UTC)
Maybe some of the foregoing should be move out of the way to talk:gravitational time dilation?--Light current 04:27, 16 September 2006 (UTC)

Eye exercises[edit]

Anybody know any good ones? I've been doing some of my own devising, and they're working, but I'd like to know of others. The google sites I found were all commercial. Anchoress 05:03, 14 September 2006 (UTC)

Too much Wikipedia reading? —Bromskloss 07:48, 14 September 2006 (UTC)
LOL well, too much computer work I think (while wearing my glasses rather than my contacts). Anchoress 08:49, 14 September 2006 (UTC)
Presumably you've tried the Bates method, which is supposed to be good, but I can't speak from experience.--Shantavira 08:21, 14 September 2006 (UTC)
No I haven't, but thanks for the link. I'm not trying to wean myself off glasses/contacts, I'm just trying to restore the full range of functional motion (focus) to both my eyes. I've just noticed that my peripheral vision is asymmetrical, there's a few degrees in the range where I can't focus, and my dominant eye is becoming more dominant, my weaker eye weaker. Anchoress 08:49, 14 September 2006 (UTC)

My general impression from years of experience and research is that there is nothing you can do. My optometrist said that, years ago, myoptic vision used to improve as you went over 50, due to shrinkage of the eyeball. Now, with computers, it rarely happens. --Zeizmic 17:11, 14 September 2006 (UTC)

Huh? LOL. As I said above, I'm not trying to fix myopia. I'm trying to strengthen my eye muscles, which (again, as above) seems to be working. What I meant by 'too much computer work' was not that it was causing myopia, but rather that (esp with my coke-bottle glasses rather than contacts), I was using a smaller range of motion and less varied focus lengths. Anchoress 17:15, 14 September 2006 (UTC)

As we sgould always say with Wikipedia, this is not the place for medical advice. But if you have noticed changes in your vision, it might be a sign of something needing medical attention. An optometrist or opthalmologist can test your peripheral vision. Changes in your visual field can be a sign of some neurological serious conditions. Vision changes can also be a sign of diabetes. Edison 18:05, 14 September 2006 (UTC)

Yeah I know all that, but I'm just asking if people know any good eye exercises :-). I've had a recent eye exam. I'm not asking for medical advice. Anchoress 18:08, 14 September 2006 (UTC)
How much improvement have you seen? --Proficient 05:51, 15 September 2006 (UTC)
Well I've been doing them every day for a week, and here's what's happened so far:
  • When I started some of my eye muscles were so weak they got sore from the exercises, and now they don't at all;
  • My range of vision is already greater;
  • When I started there were places in my field of vision I couldn't get my eyes to even move to, the muscles were so weak; that's pretty much gone now;
  • I have more control over movement outside the normal range of motion (as in looking as far to one side as possible);
  • When I do the exercises my sinuses drain and I feel really refreshed.
That's it so far. Anchoress 06:02, 15 September 2006 (UTC)
Now I'm curious. What exercises of your own devising do you use?---Sluzzelin 06:57, 15 September 2006 (UTC)
Hey, I’m the one asking for help, lol. But it’s probably a good idea for me to write them down, I’ll do my best to describe them.
OK, so some caveats; first, this is not medical advice. For medical advice, consult an Optometrist or Ophthalmologist. :-) Second, I have no idea if I’m using the right words to describe what I’m doing, so please don’t flame me if I describe something in a goofy way.
All the exercises I do are to stretch the boundaries of my peripheral vision and to strengthen the muscles that control movement and focus.
  1. Imagine the outer boundary of your vision as a big clock. Sitting comfortably, preferably somewhere where your view to both sides is symmetrical (I sit in the middle of a room), look along the boundary of your vision in overlapping 90 degree arcs. First look up at 12, then carefully along the boundary down to 9, then back to 12. Repeat 6 times. Rest and take a breath. Then do 12 to 3 six times, then 6 to 9, then 6 to 3, with a break and a breath in between each. Make the movement slow and smooth like a fastish second hand. Note any places where your eyes jump or fail to focus. Gently push to keep your vision as far out as you comfortably can. Note and correct the tendency to move your head. Then overlap by going from 10:30 to 1:30, 4:30-7:30, 7:30-10:30 and 4:30-1:30.
  2. Now go in straight lines, from 12 to 6 and back six times, 9 to 3, 10:30 to 4:30, and 1:30-7:30. Don’t just jump from one to the other, focus on all the objects along the path. Take a breath break between each pair of coordinates. Take a second to do your best to focus at each end. Keep your head still.
  3. Now go in a big circle, three times clockwise, then 3 times anti-clockwise, then repeat. I don’t cover an eye each time, but I do concentrate on switching between my dominant and subordinate eyes. Meaning, the first six times around I’m concentrating on using my left eye, then the last 6 times my right.
  4. I do some crossed-eyes stuff, just fooling around, that’s difficult to describe. If you ever saw Madeline Kahn in the credits of – Blazing Saddles I think – it’s like that.
  5. I should also say that the first few times I did these exercises they made me kinda nauseous.
I’d like to learn some other exercises, particularly the ones that are supposed to be so good that utilise differing focus distances. I just don’t know how to do them, so I’m not bothering to make up any exercises for them.
Hope that helps. Anchoress 17:59, 15 September 2006 (UTC)
I see. Yes it does help, thank you. FWIW, I try to perform (very rudimentary) focus exercises daily. I always sit near a window when using the computer and, every half hour or so, I look outside for a minute (it helps when there's daylight outside). I try to focus on things in the distance and observe them consciously without thinking of anything else, watch clouds, mountain tops, buildings, cranes. While commuting, I sometimes look outside the train window and switch back and forth from close to distant without moving my eyes or head by focusing on a smudge on the window and the distant horizon respectively (and perhaps an intermediary target as well). I used to enjoy looking at the Magic Eye Autostereogram books, but got tired of all the dolphins and dinosaurs after a while. ---Sluzzelin 02:02, 16 September 2006 (UTC)
Cool, glad it was of interest to you. I do a couple of little focus exercises every now and then, one of them in the loo, :-). But unlike the other exercises I do, which I can 'see' the results of very very clearly, I have no idea if the focus exercises are helping, which is why I'd love to find some that have had actual results, or that were developed by experts. Anchoress 20:33, 18 September 2006 (UTC)

Gravitational pull between moving objects[edit]

Is it possible that I can detect a small attractive force between two staffs when I spin them close and parallel? They are made of aluminium, so are fairly light, about 5 feet long and two centimetres in diameter. It feels, once I have them close and parallel, like it suddenly requires less effort to keep them there. The 'spinning' I describe is a little like Chinese stick fighting manouvres, one staff in each hand. 10:19, 14 September 2006 (UTC)Steph

No, you wont be feeling the gravitational force between them. Without actually being there and seeing what is going on I doubt I can help explain it much. Hopefully someone else has experienced this same thing and can explain it.

There is probably some air coupling going on. --Zeizmic 12:06, 14 September 2006 (UTC)

Isn't that what passenger pigeons used to do ? :-) StuRat 13:54, 14 September 2006 (UTC)

And geese in a V-formation. --Zeizmic 17:06, 14 September 2006 (UTC)

Sounds a bit like drag cup but thats a rotating magnet inside an aluminium cup (use as a speedometer in the past)--Light current 17:13, 14 September 2006 (UTC)
First of all, spinning will not have any effect on the gravitational pull between bodies. Secondly, the force of attraction between any 'normal' (not massive) bodies will be very very less and can be detected only with precise measuring instruments. So I don't think that you can actually feel the attraction between the staffs - Wikicheng 07:11, 15 September 2006 (UTC)
You can even do it mathematically - the gravitational force between two objects is (from gravity). Plugging in some reasonable numbers (each staff weighs about 0.5 kg, and say they are 20 cm apart) and the force between the staffs is 4.2x10-11 N. This is 200,000 times less than the weight of a flea. So, really, not very much... — QuantumEleven 11:10, 15 September 2006 (UTC)

Ok, I accept that the maths above is probably accurate - Thanks. But another phenomenon, which I have observed but never had explained, might be related - That is, when two streams of water are falling close to each other, the streams seem to come closer to each other the further the water falls. So if they are, say, a half a centimetre apart at the top, they come together to form a single stream after a metre of falling. To me it seems there is some kind of attraction going on, but the water must have a similar mass to the staffs. Does that help at all?

Think hydrodynamics, not gravity. ---CH 04:28, 18 September 2006 (UTC)
This has something to do with low pressure created by moving fluids. See Bernoulli's principle. A google search on this will yield and many other interesting sites -- Wikicheng 04:41, 18 September 2006 (UTC)

It is starting to come together - the fluid theories would also apply to fire? I didn't say earlier, but there is a burning wick each end of the staff. Maybe that is the key ingredient, rather than the staffs themselves. I am thinking along the lines of - the burning wicks comsume oxygen in the local area, resulting in an area of low pressure. This would occur equally all around each wick, but when two wicks are close to each other, the area between them would be the lowest, resulting in a tendancy for the wicks to move towards each other. If this occurs at both ends at the same time, the staff draw together. If that sounds completely wrong, I welcome further criticism. Thank you all for your help so far!


Why is sulphur used for making skin ointments? Thanks!

Because it smells so nice ? :-) StuRat 13:52, 14 September 2006 (UTC)
But seriously, I suspect that, being an irritant, it causes the top layers of skin to fall off. "Beauty can be ugly." StuRat 13:52, 14 September 2006 (UTC)
In the 1940s before modern antiseptics became available, I think sulphur was used. Perhaps it is used for this reason, and to stop things growing in the ointment. But I'm only guessing.

earth science[edit]

what are the composition of lithosphere ?kellane hannam

We really like to see the teeniest bit of effort here. This is an encyclopedia; it has stuff. Think it through! --Zeizmic 12:04, 14 September 2006 (UTC)
  • Zeizmic means you should take a look at the lithosphere article. (note: your question should read "what is..."). - Mgm|(talk) 19:36, 14 September 2006 (UTC)

I knew somebody would be a softie, but perhaps they will learn enough to see that there is no simple answer. --Zeizmic 22:00, 14 September 2006 (UTC)

The principle components of the Earth's are protons, neutrons, and electrons. They tend to be organized into frequently repeating elements and lattices. There are probably a lot of liths there as well. Saturn's lithosphere is trivial. -- Fuzzyeric 04:02, 15 September 2006 (UTC)


Could anybody tell me how many tentacle housefly has does spider, earthworm ??

Do you mean how many legs do they have ? Insects (including flies) have 6, arachnids (including spiders) have 8, and worms have zero. StuRat 13:49, 14 September 2006 (UTC)
Maybe he is referring to the antennae? If so, houseflies have two antennae, spiders and earthworms have none. Gary 19:00, 14 September 2006 (UTC)
Maybe setae? Which is trickier to count, and varies from species to species. —Pengo talk · contribs 01:48, 15 September 2006 (UTC)
Nobody seems to want to assume he was actually talking about tentacles, to which the answers would be zero, zero, and zero (one?).  freshofftheufoΓΛĿЌ  02:22, 15 September 2006 (UTC)

Fordson tractor[edit]

Henry Ford introduced the Fordson tractor in 1917 but started experimental work in 1915 - 1916. I have a picture of one of these experimental tractors and it looks diffrent than the production model, it appears to have a diffrent engine. Do you have any information about what engine was used? Did Ford buy some engines from other companys such as continantal for the experimental tractors? Thank you for any help you can give me.

Actually Ford built his first prototype "automobile plow" in 1907 (See image at [1]) Since Ford was the probably the largest single maker of engines in the world and that Ford's policy was devoted to producing every part in shop from raw materials (except tires), it is hard to imagine them going to another supplier for an engine, even for a prototype. Rmhermen 15:50, 16 September 2006 (UTC)

Is this a Dracaena?[edit]

Is the houseplant pictured at right a species of the Dracaena genus? If so which species/cultivar? The closest match seems to be Dracaena marginata, although the habit is somewhat different. Additional photos or verbal description can be posted if necessary. Thanks. --Theodore Kloba 16:46, 14 September 2006 (UTC)

It looks to me somewhat like a Beaucarnea recurvata, or something from that genus. BenC7 06:42, 16 September 2006 (UTC)

looking for medical word ...[edit]

... that means subcortical seat of subconscious memory.

It sounds phonetically like emiglia ... 19:36, 14 September 2006 (UTC)

Amygdala. -- Finlay McWalter | Talk 19:38, 14 September 2006 (UTC)
That's Princess Amygdala to you. Clarityfiend 01:49, 15 September 2006 (UTC)


Could someone explain why certain colours when put together, form patterns? Specifically I'm referring to Image:Visiblecolour.svg on Commons, small version: Visiblecolour.svg, which I can see a kind of + (plus) shape when looking at the yellow hue values and the cyan. I thought it might have been just me but asked others who said they could see them too. It's not very pronounced but is definitly visible. Why do those particular colours create the illusion of that shape? (I don't see it on any other parts). Or is it a flaw in the image? - Рэдхот 21:50, 14 September 2006 (UTC)

It's an artifact in the image. The person who made that image made it out of a single gradient object, but the object has 7 points on it, and the colour curve is kinda flat at those points. -- Finlay McWalter | Talk 22:07, 14 September 2006 (UTC)
It's an artifact of the way colour is displayed on an RGB monitor. To make red, green, or blue, you crank up that single colour of pixel up to 100%. To generate cyan or yellow you combine green and blue or red and green—in this case, it was done using the 100% maximum intensity of both component colours. Consequently, the yellow and cyan appear very bright. TenOfAllTrades(talk) 22:11, 14 September 2006 (UTC)
There may be artifacts in the image, but I have noticed that some color regions seem wide, like blue, red and green, while others seem narrow, like yellow, orange, cyan and violet. Does everyone see this same difference ? I've noticed the same thing when looking directly at a rainbow. StuRat 07:43, 15 September 2006 (UTC)
Yeah, I've wondered about that too. If this image shows an objective representation of colours and we see green as a broader band then the logical conclusion would be that we don't differentiate very much between the different shades of green. But that doesn't make sense if our specific colour perception evolved when we were swinging around in trees. Wouldn't it make more sense for us to actually differentiate better between those shades of green, helping us to disitnguish the various types of vegetation that surround us? DirkvdM 08:29, 15 September 2006 (UTC)
I'm sure Wikipedia has an article on it somewhere. Try Color space or gamut or XYZ colorspace. Basically, computer monitors cannot display the full range of colors that humans can see, and because of the way they work, they've got better coverage of the greens than of any other color. --Serie 21:45, 15 September 2006 (UTC)
But I see the same thing when looking directly at a rainbow, so I don't buy that argument. StuRat 00:01, 16 September 2006 (UTC)
Cool thanks for all the answers. I actually made the image myself which is why I wanted to know. I checked several times to make sure there wasn't a flaw in the gradient and couldn't find one, so thought it might have been the screen. - Рэдхот 11:59, 15 September 2006 (UTC)

Expanding universe[edit]

Almost everyone agrees the universe is expanding. THe question is: into what is it expanding?--Light current 22:27, 14 September 2006 (UTC)

Eternity? I guess once the universe has expanded into it, it's called outer space. I don't know what it's called before the universe got there though.---Sluzzelin 22:46, 14 September 2006 (UTC)
A really (infinitely?) huge vacuum? - Dammit 22:57, 14 September 2006 (UTC)
(edit conflict) No the huge vacuum is the universe, outside the universe the are no dimension (no spacial or time dimensions) so it is impossible to exist outside of it, so there is not anything outside of, not just space, there is no space outside of it, there isnt anything for it to expand into, its not expanding into anything, its just getting bigger. The outside of the universe is not atached to the universe by a time structure, so there can be no concept of movement of the boundary. And anyway the universe doesnt have edges. The whole thing is pretty complicated really, but here goes;
  1. the universe in a boundary-less, yet finite in size object.
  2. it is getting bigger
  3. there is nothing outside, not because it hasnt got there yet, but because it is impssible to exist outside of it
Basically anything that is possible for you to percieve is inside the universe. All the space and time are inside (various) universe(s) but, these universes, are all the same universe, which ahs collapsed, and expanded an infinite amount of times, but, due to the fact that time structures were destroyed every time aswell, there is no relation in time between these universes, so every universe is happening ate every point. Hmm, basically, yeh its expanding, nah theres nothing out there (atall, not even a vacuum, because thats something). Philc TECI 23:11, 14 September 2006 (UTC)
Who says it has to expand into anything? See Metric expansion of space. Consider this: if the universe were in contact with something "outside", wouldn't the outside be part of the universe too? Melchoir 23:06, 14 September 2006 (UTC)
So is the universe expansion due to the galaxies moving away from each other (due to the initial big bang etc) OR is it just the space between them expanding for some reason? --Light current 23:17, 14 September 2006 (UTC)
Unfortunately for the refdesk's purposes, why is still kind of an experimental question. Dark energy is an okay place to start. Melchoir 23:25, 14 September 2006 (UTC)
Even if nothing exists outside the universe, as explained above, can we still have a word for it (something better than 'non-universe' perhaps)? After all, we human beings like having names even for things that don't exist.---Sluzzelin 23:23, 14 September 2006 (UTC)
Multiverse (science)? Melchoir 23:28, 14 September 2006 (UTC) about nothing? Clarityfiend 02:15, 15 September 2006 (UTC)

The real answer is this: nobody knows. However, there is one thing that we can be fairly sure of: space isn't static. That is, the galaxies, when we speak of the expanding universe, are not actually hurdling through space, but rather space itself is expanding. In addition, this expansion appears to be accelerating. One might expect the universe to either slow down, or stay at constant speed. Yet this is not what is observed. Things appear to be speeding up, which may in time clue us in to exactly what is going on "beyond" our universe, if there is such a thing. - R_Lee_E Flag of the United States.svg (talk, contribs) 23:26, 14 September 2006 (UTC)

Not 100% true. The various galaxies are moving with respect to each other, in addition to the expansion of the universe. I think we're scheduled to gulp down (yeah, that's the scientific term) the Magellenic Clouds at some point. Clarityfiend 01:37, 15 September 2006 (UTC)
Yes. That is why I said, "when we speak of the expanding universe." - R_Lee_E Flag of the United States.svg (talk, contribs) 01:44, 15 September 2006 (UTC)
Sir! Yes, sir! Clarityfiend 02:17, 15 September 2006 (UTC)
It's expanding into the future. Really. Consider the common "surface of an inflating balloon" model. Run the film backward and it contracts into the past. Run it forwards and it expands into the future. This really is what's going on.
Of course, there are two things going on... The observable universe has a radius of ~13.7 Gly (billion light years) because our past light cone extends far enough to see that far away/back. Inconveniently Hubble's law induces in-place expansion and details of that theory lead to estimates of 46-78 Gly. The first effect is similar to the balloon model. The second would be similar to some weird force causing the surface of the balloon to get wrinklier and wrinklier. -- Fuzzyeric 04:11, 15 September 2006 (UTC)
I also wondered about the (im)possibility of expansion of something that has to be assumed to be of fixed size when I was a kid and that (plus other thoughts) eventually led to my alternative to the Big Bang theory. But assuming the correctness of the theory of a Big Bang leading to an expanding universe, it is quite immaginable that there is another 'universe' that grew from another Big Bang. If they both expand, then could these ever touch? If so, how could their distance be expressed if there is nothing between them? And if there is no 'expressable distance', then how could their approach be expressed? And if that can't exist, then how can they ever meet or have been apart? DirkvdM 08:45, 15 September 2006 (UTC)
Two parallel patches of Flatland can approach each other and (perhaps) pass through each other. The distance between them is inexpressible because the only directions in which there is distance in either universe is perpendicular to the direction of separation. Imagine that the answer to the principle question were "3 meters"; then the follow-up question is "in which direction", which is unanswerable. Now, if there is brane cosmology then this could be exactly the situation in which we find ourselves, but (hopefully) measurable dynamics would set a metric in the direction of brane separation and so "distance" could be meaningful, i.e. would set a norm (mathematics). -- Fuzzyeric 03:06, 16 September 2006 (UTC)

brain disorder[edit]

my sister had a CT of her brain and they found dark area in the frontal lobe. Is there a specific disease that this is a symptom of? She has frequent "migraines" which they have been treating for yrs. She has some speech difficulty, ex; finding the right words, etc. Any info will be greatly appreciated Thanks ahead of time. 23:58, 14 September 2006 (UTC)

There's no single disease that's associated with a "dark area" on a CT: there are lots of different problems that might cause such a finding. A dark area is an area that is relatively more permeable to x-rays than the light areas. You need the radiologist or neurologist who actuallu looked at the x-ray to tell you what they think it might be, there's no way to tell from just a description. They will also be able to suggest if there would be any value to further studies like a CT scan with contrast, or an MRI. - Nunh-huh 04:36, 15 September 2006 (UTC)