gib65

Right, and who's to say the fourth dimension isn't time? I sometimes like to think of the radius of the 4D sphere universe as time.

Oh, that makes a bit more sense. So then the curvature of the universe must be extremely large, and its rate of expansion in the beginning extremely fast.

I just learnt that the geometry of the universe has recently been measured. It turns out to be Euclidian after all (as opposed to spherical or saddle-shaped). I learnt it here, a course you can order on cosmology, taught by Mark Whittle. Whittle says this: "The geometry of the universe, as best we can measure, is Euclidian. Giant triangles do add up to 180 degrees. Giant sphere do have surface area 4(pi)r^2, and volumes (4/3)(pi)r^3. All the geometry you learnt in high school applies not only to surveying your property, but also to surveying billion light year galaxies maps." What are the implications of this? Thinking of the 3D universe as the surface of a 4D sphere was convenient because I didn't have to ask where the ends of the universe lay. No matter which direction you travel, you eventually end up back at the same spot you started. Now I have to question what would happen if I kept moving outward indefinitely. Would I end up reaching an area of space that was devoid of matter and energy? Would matter and energy continue to surround you no matter how far out you went (I doubt it considering this would mean an infinite amount of matter and energy exists)? Would I suddenly hit a "wall" - the edge of the universe, so to speak (I doubt this too)? What does this say about the creation of space itself. As the 3D surface of a 4D sphere, one could imagine that space was created with the Big Bang, but in a Euclidian universe, it's hard to imagine how space was created (unless one imagined that there really is an expanding edge to space). Can anyone shed light on these questions?

Ah, so an electron just is energy; not convertable to energy (in the form of a photon). But still, the question lingers: has any material particle (electron or quark) ever been converted to energy (i.e. in a usable form) experimentally? I mean, one of the reasons E=mc2 is so exciting is because it points towards the potential prospect of actually harnessing huge quantities of energy from only small amounts of matter. Is there any hope of this at all?

So E = mc2 right? That means that matter can be converted to energy, and visa-versa. What particles does this apply to? It must apply at least to electrons, protons, and neutrons, which in turn means it applies to quarks. Now what form does this energy take once an electron or quark is converted to it? Would it be a photon? How many photons per particle? This must mean that electrons and quarks can be converted into photons and visa-versa. Am I right?

So then what is an "action potential" precisely?

And would muscle cells do it the same way as nerve cells? I mean, do they have action potentials that travel down their length (consisting of sodium and potassium ion channels opening to allow an inverse in charge to occur between inside and outside the cell) and neurotransmitters released at their ends that bind to receptors on the adjacent muscle in order to begin the process again?

Are neurons the only cells in the body that are capable of transmitting electric signals?

What definition do you think would make the most sense in the context of my question?

When did language first evolve? Was it the result of a genetic mutation or did man always have the genetic capacity for language but only develop it fully later on?

But it can be done, right?

What does it take to remove the salt from ocean water. I was just thinking if this were possible and cost-effective, it could solve the world's water shortage porblems. What's stopping us?

When the brain develops a tolerance to certain drugs, is there a limit to how tolerant it can be? I ask because I develop a serious tolerance to caffein, and when that happens, it doesn't matter how much coffee I drink, I'm just crashing. I have to abstain from it for a week to get back to my normal level (after which point, one cup of coffee will send me buzzing for 18 hours). The crash usually last about 3 days, but that's usually only after several days of drinking coffee. If I have a few cups on just one day of the week, I don't notice much of a crash at all afterwards. For this reason, I'm always perplexed how others can go day after day drinking 3 or 4 cups of coffee and aparently function normally. No one I've asked has ever reported experiencing crashes due to their tolerance being too high. So I'm wondering if there's such a thing as one's tolerance reaching an upper limit so that they can drink however many cups of coffee they need to stay alert and their tolerance doesn't go any higher. That way, we could say they've reached their daily amount which will be the same amount they'll need day after day from here on in. Maybe my daily amount is just extremely high (I've heard of people who need upwards of 10 cups of coffee to keep them going through the day).

I always assumed puss was white blood cells until someone told me it wasn't. She told me she'd seen white blood cells and it look like a clear yellow liquid (like urine). I still wagered that puss could be white blood cells because the urine looking solution she saw may have been very diluted with water, making it translucide, and that perhaps puss is white blood cells that have captured bacteria or viruses rendering them more opaque (like clear garbage bags that have been filled and are been purged). So what is puss?

I'm not sure if this is what swansont said - he's rather cryptic at times (no offense swansont), but from what I understand, you only get amplitude when you have a whole stream of photons - the reason being that amplitude = the number of photons. BTW, I've always wondered how E is said to come only in descrete units when f is a continuous quantity. Couldn't you make E whatever you want by plugging in the right value for f in E = hf? Does the quantization of E assuming that f is fixed (and that we have a constant k standing for the number of photons: E = khf)?

Hello, Last weekend I got a splinter in my finger. I hardly noticed it at all until a few days later when it started to hurt a little and the skin around it turned red. I ignored for the longest time, but it kept getting worse. Now my finger is all puffed up. It's dark red at the center, a circle of white puss around it, and a large area (about a centimeter and a half in diameter) of red - almost purple - around that. I hurts to bend my finger and it hurts to touch it. Is this something I should worry about? Go see a doctor about? Will it heal itself in time? I also want to know, just our of pure curiocity, what my system is doing. How does it get rid of splinters and other foreign debris in the skin? What's the point of swelling up with blood and puss?

So what about solar panelled houses? I've heard stories of people who could live comfortably in houses powered exclusively by solar panels, but this probably entails no top-of-the-line entertainment systems or a TV and computer in every room or things of luxury like that. No?

Have they invented fossil fuel free car yet? A car that runs on solar energy or electricity or something green? I know the answer is obviously 'yes' but I'm wondering how much milage can one get out of it and how cheap is it to use and maintain? In other words, would it be to the advantage of the average consumer to purchase one?

Right! Now that I think about it, what we'd probably see is the star becoming more and more faint. In fact, we do see this. The distant stars are the harder ones to make out. Am I right in thinking this is due to the concentration of photons becoming less and less?

Yes, I'm familiar with GR. I've also heard that massive rotating objects will not only bend space and time towards itself but will twist them in the direction of their rotation, and that this can somehow create loops in time that could take one into the past. I'm not sure how this works but it sounds similar to the quote above. Is it the same idea?

I found this excerpt on the internet and I want to know if it's true: Is this true?

But I thought there was no difference. I thought the wave nature of particles derives from their superposition. That is, the wave is made up of a superposition of the particle concentrated at the highest amplitude of the wave. Is this wrong? Merged post follows: Consecutive posts mergedIt doesn't seem like this thread is progress too fast, so let me just cut to the chase: If I'm right that light waves constitute photons in superposition states, and that in order for them to be intercepted by the human eye, it must interact with a molecule in the retina, thereby causing it to collapse (or be absorbed), then there must be billions upon billions of photons just in one's local vicinity. At least, this is the case when the photons in question come from distant stars. When I look up at the stars at night, I don't ever fail to see them - regardless of when it is or where I am - at least for the ones bright enough to see. This blows my mind when I think about the odds of a single photon being emitted by the star, traverse the great expanse of space between it and me, and happening to finally collapse upon interacting with a single molecule in my retina, a molecule out of trillions of others in interstellar space that it could have interacted with. Now, these odds might not seem so striking if we consider that there are billions and billions (probably more like trillions and trillions) of photons being emitted by the star in question. With that many photons, the odds of one interacting with molecules in my retina are not that far off (are they?). It might not be that far off even when we consider that it isn't just a single photon interacting with my retinal molecule just once in momentary interval of time, but a whole stream of them constantly interacting with the same molecule such that I can see the star at any time in the night and at any angle I direct my eye and at any position on the Earth's surface. Add to that that there would have to be plenty of photons left over for billions of other human beings (and other animals) to see the same star. But I would think that there would have to be a point at which the star becomes so distant that the odds of one of its photons hitting the eye would become noticeably deminished - such that seeing the star wasn't always guaranteed. It would have to be a point at which one would look up at the star and sometimes see it (if he were so lucky as to have the photon interact with his retina) but sometimes not (if he weren't so lucky). There would have to be a noticeable chance that while one person sees the star at one moment, another person right next to him wouldn't. Is this what would happen if the star were distant enough and the number of photons limited to a certain amount?

When you look at the stars at night, you can see any one of them no matter where you are and no matter what time of night it is. This is possible becomes photons are emitted from these stars and they travel as waves until they reach your eye and interact with your retina. Is this interaction an example of the way the wave form of a particle collapses and becomes more like a tiny point in space that interacts only with things local to it? I have a follow up question, but let's start with this.

OK, makes sense. I don't know why I thought it couldn't move past the second generation and remain dormant. I just remember learning it that way.

I'm use to thinking that a recessive gene only survives as dormant through one generation. Is that wrong? Can a recessive gene be passed on through two generations and not show up as a phenotype, and then show up in the third generation (i.e. in one's great grandchild)?