gib65

So where would I be able to purchase some of these things? I called around to various places but most people have no idea what I'm talking about. Someone at Canadian Tire mentioned "Quick Start". Does anyone know about this?

I think this goes under classical mechanics (it's classical physics anyway). Suppose I had a cooky try with 1/4 inch deep water in it. If I let it sit on the kitchen counter, would it eventually evaporate? If it would, how long would it take? If it wouldn't, what conditions, in addition to those listed below, would be needed? My house is a little above room temperature (25 degrees celcius). I live in Calgary, Alberta, Canada which is at an altitude of about 1 KM above sea level (and I live 5 stories up). It's the spring season with temperatures around +20 celcius (on good days). What if I left it out on the balcony on an average day (~20 celcius with mild winds)?

Is this a Naptha product?

I'm sorry if this should go in the inorganic forum, but petroleum ether sounds like an organic compound to me. Anyway, this may sound like an odd question, but can one get petroleum ether from a local commercial outlet, or is there a lot of restriction to obtaining it? I live in Canada, BTW.

Thanks everyone. Makes sense now

What's the meaning of "proof" when it comes to alcohol? I thought it meant percentage of alcohol but then read something that said 150 proof. So what does it mean?

By "unchanged" I mean in terms of our genetic coding. But I guess genetic coding is always changing too. That trend you mention of female pelvic size becoming more adroid probably has something to do with selective breeding which would in turn select specific genes to be passed on. But what I'm talking about is genetic mutations. When was the last time the human species as a whole went through a genetic leap by way of mutation. The 50-100,000 year answer you gave is what I was after (I think). And now I have a follow up question: How long ago did oral language come into use? I've been told between 30 to 40 thousand years ago. If this is true, then oral language can't be genetically determined. I mean, if we haven't gone through a genetic leap within the last 50 to 100 thousand years, it would seem the ability to use spoken language is learnt. Is this true?

For how long has the current genome of the human species remained unchanged. That is, how old is the modern human being? I've been told we are 100,000 years old. Is this true (roughly)?

Agreed. If there was absolutely no difference between visualizing and apple and seeing one - in terms of brain activity - this would open a pandora's box of philosophical dilemmas. I suppose if you believed in free-will, this would be the Holy Grail of experimental evidence, but if you were a hardnosed determinist/materialist this would not sit well at all. To think that you could get blatantly different behavior from perfectly identical brain states is unnerving to a determinist/materialist. I mean, you can easily ask someone to raise their left arm (for example) if they were merely visualizing an apple, but raise their right arm if they were actually seeing it - obviously different behavior. But then you bring the MRI into the scenario and observe that, in both cases, there is no difference in brain activity whatsoever, and you become want for a physicalistic explanation for what's really causing their arm - either the right one or the left - to be lifted.

I know that quantum phenomena (superposition, uncertainty principle, quantum entanglement, probablistic outcomes, etc.) is readily observed in measurements of the states of fundamental particles. How readily are these phenomena observed at higher scales? Take atoms, for example. Has anyone ever observed atoms in superposition? What about complex molecules? Groups of molecules? How far up the ladder of scale can one go before quantum phenomena become practically unobservable?

So, tell me something. Have brain scans ever turned up observations showing any difference at all between visualizing something and actually seeing it? I mean, is there any difference in the brain activity when someone looks at an apple (say) compared to visualizing that same apple, or is the brain activity under both condition EXACTLY the same?

Yes, I've noticed this too. Something interesting that I noticed about this - and I don't know if there's anything to this (maybe you could enlighten me) - is that the most useful graphs are those based on nodes and connecting edges or arrows. For example, the structure of a business is often depicts by departments represented by nodes, and the way these departments interact with each other represented by arrows (a flow chart, essentially). This is uncannily like the networks that neurons form with each other where the nuclei represent the nodes and the axons represent the adges. Could it be that graphs of this sort work so well because they literally provide the brain with a complete and precise "blue print" for how to build a neural network - one that, when built, will make possible the understanding of the concepts represented by the graph? Do you think that the PFC "queries" the other, more sensory/perceptual areas of the brain for information? I have this idea of querying that seems to explain this. That is, if the PFC wants to visualize something, it needs information on how to build such a visualization. For example, if it wants to visualize a house, it needs to know what a house looks lke vis-a-vis lines, shapes, colors, textures, etc. Therefore, it "queries" the more sensory or perceptual parts of the brain for information on how to do this. Do you think this sounds plausible?

I was thinking about string theory the other day, and I thought that some of the details of string theory have implications for quantum physics. In particular, I was wondering if the vibration of strings can account for the "unstable" nature of states that particles can be in. For example, could something like spin change its value depending on exactly what state the vibration of a string was in? I don't really know the relation between spin and string vibrations, but I suspect that vibrations, being so variable as they are, must have variable effects on our measurements of particle states. Also, some string theorists believe that strings can vibrate in up to 10 or 11 dimensions. I was thinking about this, and I also thought about the concept of worm holes - that is, the idea that if one traveled through a worm hole, one would almost instantaneously travel from one point in space to another. That is, traveling through a worm hole is like "trans-dimensional" travel. Now, thinking about this, and thinking about string vibrations in multiple dimensions, I thought that a string could potentially extend itself, through its vibrations, into one of the 10 or 11 dimensions and, supposing these extra dimension it extended into was like a worm hole, it could poke its head out somewhere else in the common 3 dimension of our space. That is to say, a crest in the vibrational wave of the string could have a high enough amplitude that it reached far enough into the extra dimension that it reappeared elsewhere in "normal" space. Could this not account for the phenomenon of superposition? Just a few thoughts, but I would like to hear what other people think. Is this line of thought plausible? PS - I realize not everybody buys into string theory - I'm not particularly settled on the matter myself.

Ah, well I see that 'hidden variable theory' carries very specific connotations that can be disprove. I suppose I misused the phrase 'hidden variables', but the way I meant it goes beyond the scope of the conventional theory. Let me explain: "No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics." This is obviously from the link you provided. The key words in this quote are "physical" and "local". If hidden variable theory purports that there are physical and local - yet hidden - variables bringing about the quantum randomness, then I can see that being disproved. But what I meant by 'hidden variables' was something more abstract or metaphysical, not something that had to be physical and local. Also, I meant that such factors could not be disprove in a purely logical sense (i.e. one cannot make a purely logical argument proving that an unknown explanation doesn't exist for what appears to be random outcomes - the best you can do is show that we don't have an explanation yet). An example of an abstract, non-local explanation is to suppose God decides the outcomes of quantum phenomena. Don't worry, for the moment, whether God really exists or not - I don't believe in God myself (at least, not the conventional notion of 'God'). But for the sake of argument, suppose there was a God, and He decided the outcomes of quantum phenomena based on the roll of a dice. Also, suppose that the dice adheres to all the laws of physics. That is, it falls due to gravity, it rotates in the air according to the initial angular momentum given to it by God's hand, and when it lands, it obeys the laws of collision and impact with the ground - and it finally settles on one particular side. Therefore, the outcome of the dice is purely deterministic, but too complex for any human to notice a pattern. Furthermore, suppose God never deviates from the scheme of letting the dice decide the outcome of the quantum phenomena. So here we are performing quantum experiments, and there God is watching us, saying "Oh, great, those humans are at it again. Well, better get the dice out." So we conduct the experiment, God rolls the dice, and yields a 6, and so whatever a roll of 6 dictates for the results of the experiment, God sees to it that this result is indeed what happens. Now, say what you want about metaphysics. But if you keep in mind that my version of 'hidden variables' is meant in a purely logical (i.e. non-physical, non-local) sense, you see that it becomes a lot more difficult to disprove.

Well, does anybody know what that phenomenon is called, at least? That is, the phenomenon of the sensory cortex becoming active just by visualizing objects?

I guess, in a certain sense, spoken language can stir up our emotions and music can make us think. I still think music is better suited for effecting us emotionally though - just as spoken language is better suited for communicating ideas. Well, to a degree. Ah! Let's be careful. Let's not confuse musical listening with musical ability with emotions. What I'm curious about is strictly musical listening and what part of the brain (most of the time and generally) it is associated with. Yes, my question does concern emotion as well, but as far as this is concerned, I'm not that interested in where it is found in the brain (although it would be interesting to know). This is true. Makes sense to me. Fair enough. Although this doesn't QUITE answer my initial question, we are headed in the right direction.

Well, that's interesting. So do you mean to say that the genuine 'hidden variable' theories purport that there is absolutely NO room for randomness? How could such a theory be disproven? I can see a theory that predicts specific and well defined variables being disproven. For example, if I had a theory that little microscopic gremlins are responsible for the pseudo-random outcomes that we see in the quantum realm, then it's very possible to disprove that theory. But the idea of undefined variables that we simply haven't discovered or thought of being disproven seems logically impossible. How can you disprove that there might be an explanation for something that we just haven't figured out yet?

You've missed my point entirely. I'm not saying randomness and proabability are incompatible. I am saying' date=' however, that [b']complete[/b] randomness (i.e. there being perfectly equal chances of every possible outcome) is incompatible with asymmetrical probability (i.e. there being more of a chance of one outcome over other outcomes). But you're right that the latter will still fall short of having perfect predicting power, although it will be more useful in predicting outcomes than complete randomness. My point is, when you have "asymmetrical probability" (my term), it's a good sign that there are at least some hidden variables bringing about the asymmetry. In other words, if the probability is leaning in a certain direction, there a pattern of outcomes emerges. This pattern may not be perfectly clear with well defined parameters, but it becomes more noticeable the more asymmetric the probability. If there's a pattern, there is probably something determining the pattern, and those are the hidden variables. Note that I'm not saying that asymmetric probability MUST mean there are hidden variables, just that it's a good sign that they exist. Also note that I'm not saying ALL of it can be traced o hidden variables, just enough to account for the asymmetric probability.

Uh... sure. You know' date=' Wernicke's area - the small section at the junction between the temporal, occipital, and parietal lobes on the left side of the brain. It seems to be involved in language comprehension. Here's a link: http://en.wikipedia.org/wiki/Wernicke%27s_area.

I have a theory and I want to know if you neuro-experts can confirm it. I believe that music is to our emotions as spoken language is to our thoughts. That is, spoken language is processed by our auditory cortex and translated into concepts. Music is also processed by our auditory cortex but translated into emotions. So my theory is that music and language serve the same function: communication - but one communicates concepts whereas the other communicates emotions. If this is right, there should be some kind of lateralization in the brain for such functions. That is to say, if spoken language is processed by Wernicke's area in the left hemisphere, there should be a part of the brain directly across in the right hemisphere for processing music and stimulating emotions. Can anybody confirm this?

Yes, good point. In fact, I've always suspected that the probablistic nature of quantum mechanics - as opposed to a completely random nature - is a sign that its non-deterministic appearance is the result of too many unknown variables interacting, making it too complex to understand. Usually, high complexity with too many unknowns results in probablistic outcomes, not complete randomness (think of the social science).

Where does thinking occur? Isn't the frontal lobe the seat of cognition? I've heard stories, however, about subjects who were asked to think of particular things while their brains were being imaged, and the parts of their brains that showed more activity were those involved in the sensual/perceptive parts. For example, if one subject was asked to think of a banana, areas in the visual cortex would become active. Or if a subject was ask to think of a song, areas in their auditory cortex would become active. But then what roll does the frontal lobe play? Could it be that the sensory/perceptive areas are active when visualizing tangible objects whereas the front lobe is active when thinking about abstract ideas?

So we know that quantum mechanics is a non-deterministic field. Something I've always wondered though is how to interpret "non-deterministic" in this description. Does it mean the phenomena in the quantum world are completely random or is there is there more of a fine grained level of probability? What is mean is - suppose you wanted to measure the position of a particle. Would you expect your results to be completely random (as is the particle could be anywhere) or somehwhat probablistic (as in the particle is most like to be in a particular region)?

That makes 5 of us. For me, it's a symptom of ADHD (or so I'm told). There are ways of learning to remember things. A good rule of thumb is if you're doing something or being told something that you aught to remember, think about it for a good 5 to 10 seconds before going off to think about something else. This will give your memory a chance to work its association magic. Of course, the trick is to know when to do this. One thing I learnt is that there is no such thing as a general technique that will improove your memory overall, but there are many little techniques that you have to learn through time. For example, I've developped the habit of remembering to look around the house for lights that I've left on before leaving or going to bed. Or I've learnt to always put my flash drive back in my laptop case the second I'm done transfering files. These are techniques that are clear insofar as knowing what to do and how to do it, and with practice it becomes habit. It won't improve you memory for everything, but over time, with enough little tricks like this, you will get a general set of learnt habits that will have a noticeable effect on your overall memory.

I remember reading back in my student years that there are neurons in the visual system that seem to be involved in our perception of left and right, and also in our North/East/South/West orientations. For example, lesions in the left/right centers of the brain result in people neglecting the left or right side of the world (they will not eat food on the left/right side of their plates, they will not groom the left/right side of their face, etc.). Also, I've heard of a little autistic girl who would not face North (actually, I forget which orientation it was, but it was one of North, East, South, or West - but let's say it was North). You could spin in circles with her, and consistently, whenever her orientation faced North she ducked her head. Does anybody know what part of the brain is involved in this?