GDG

An interesting thought for a little kid We all have pretty much the same physiological equipment, so should experience time in the same ways. Your subjective experience of time, though, tends to vary with your degree of attention and how much is going on. If you are really absorbed in a project, hours can go by without you noticing: time stands still. If you are at the opposite end of the interest/attention scale (perhaps a basic algebra class that you are overqualified for), time drags on and on... As for when your sister experienced "now", I'd have to say it was whenever she woke up. If you woke her up an hour after she went to sleep, she would not already be 30 minutes into her next morning. You just had a longer day than she did

Nope.

This is a matter of definition. "Density" is the amount of mass per unit volume; for example, water (at standard temperature and pressure, "STP") has a density of 1 g per cm3. In contrast, gasoline has a density of around 0.75 g/cm3, and mercury has a density of 13.5 g/cm3. Gasoline is less dense than water; mercury is more dense. 100 mL of water will weigh 100 g, while 100 mL of gasoline will weigh about 75 g. It weighs less by definition. The density of air at STP is about 0.0012 g/cm3. Air density varies with pressure (higher pressure raises density), temperature (density decreases with temperature), humidity (moist air is more dense than dry air), and composition (gases like CO2 increase the density). This is the principle upon which hot air balloons rely. Hot air is less dense than cold air. So, if you heat the air inside your balloon, it becomes less dense. Since the pressure has to remain the same as the surrounding atmosphere (hot air balloons are not sealed), and the volume remains constant, raising the temperature means that the number of moles of gas included must decrease: PV = nRT, or n = PV/(RT). "R" is the gas constant, and does not change. Gas (air) leaves the balloon, so that the whole system is less massive -- therefore, the air in the balloon is less dense, and the whole thing rises. Make sense?

Plus the several copies of the mitochondrial genome in each mitochondrion. Chloroplasts also have their own genomes, separate from the nuclear DNA.

A great albatross has a wingspan of over 11 feet (3 m), but weighs only up to about 24 lbs (11 kg). How big a wingspan would you need to lift a human, weighing around 70 kg? Now, how much muscle would you need just to flap those wings (add the weight of that muscle, along with the weight of the wings themselves, to the 70 kg body weight). Basically, we're a bit too big for practical flight. As for splicing avian DNA into humans, I think you'd quickly find yourself in prison.

I could not disagree more. Just for the avoidance of confusion, I am not the one opposing evolution here. I cannot agree with the use of the term "design" in this context, nor the idea that NS has a goal of any kind, short-term or not. "Design" implies an intention or purpose: there is none in evolution. NS is not an entity, and cannot have a purpose. It does not design organisms to their environment: it does not care (and in fact, there is no "it" to do the caring). In the absence of variation in the population, NS does not do any "fitting", nor does it cause the variation (although we have no doubt evolved to have natural variation: diversity is a survival trait in a changing environment). "Natural selection" is only a label for encapsulating a mathematical fact: the fact that organisms that reproduce more successfully than competing organisms will eventually dominate. I am not "throwing out purpose with the bathwater", I am deliberately rejecting it. There is no purpose in NS, it just happens. You might as well ascribe purposes to gravity, and say that it "designs" the planets. Such attribution serves only to confuse people who do not understand, and to provide support to those who would deny evolution (or science in general) in the name of religion.

Sorry, thought you already had one.

If you want to be technical about it, true. However, the H+ does not remain bound to any particular molecule for very long: the lifetime of a given H3O+ is on the order of 10^-13 seconds in water. I would call that, at best, a metastable complex. Did he say that he needed a completely naked proton?

Here are the basics: Your chromosomes are made up of DNA (there are some proteins involved, but we'll save that for another time). Each chromosome is one, long, double-stranded DNA molecule. Each chromosome is divided up into regions called "genes". The genes come in many different sizes. Each gene encodes a protein (there are some more details here that I'm leaving out for purposes of clarity). In between the genes are other regions that are responsible for regulating transcription and expression of the genes: proteins bind to these regions to turn the genes on or off. When a gene is expressed, what happens is that a complex of proteins unwinds that part of the chromosome, makes an RNA copy of the DNA sequence, and zips the chromosome back up. The RNA copy is called "messenger" RNA (mRNA). The mRNA is processed a bit (introns removed, sequence spliced in some cases, and a cap put on one end), and exported from the cell nucleus into the cytoplasm. A complex of proteins and "ribosomal" RNA (rRNA) latches onto the "start" end of the mRNA. The complex is called a "ribosome". Also present in the cytoplasm are "transfer" RNA molecules (tRNA). Each tRNA has 3 specific bases that form an "anticodon" that can hybridize to a codon (sometimes capable of hybridizing to several related codons), and has an amino acid attached at one end. There is a different tRNA for each amino acid. The ribosome reads the mRNA 3 bases (i.e., one codon) at a time. It finds a tRNA with an anticodon that matches the current codon in the mRNA, and takes the amino acid that is attached. Then it shifts to the next codon, ejects the first tRNA, and finds a tRNA that matches the new current codon. It then takes the amino acid from that tRNA, and attaches it to the first amino acid. This step repeats until you get to the stop codon. Each time the ribosome shifts down the mRNA by another 3 bases (i.e., 1 codon), it finds a tRNA that matches that codon, takes its amino acid off, and attaches the amino acid to the growing chain of amino acids. Each possible amino acid is specified by a particular 3 base code. For example, methionine is encoded by ATG. Some amino acids have more than one possible codon. For example, glycine can be encoded by GGU, GGC, GGA, or GGG. At the end of the mRNA, the ribosome encounters a "stop" codon. The tRNA that recognizes this codon (actually, there are 3 different stop codons) does not have an amino acid (and so is called "release factor" instead). So, when the ribosome reaches the stop codon, it stops translating the mRNA, releases the amino acid chain (now a full protein or polypeptide), and falls off the mRNA. The mRNA can be translated multiple times, until it is degraded by other enzymes in the cytoplasm, and the bases are recycled. The proteins can be further processed too, e.g., by having carbohydrates or other molecules added, parts snipped out by proteases, etc. Does that clear things up for you?

They do go in straight lines. If you think of it as a particle, this is clear. If you think of it as a wave, you have to keep in mind that the "wave" aspect is a variation in electrical and magnetic fields, and not a geometric trace of the photon's trail. Although this is pretty much always drawn as a wavy line, the reality is a perfectly straight line, with variations in field intensity along its length.

The easiest way to get protons is to drop an acid into water: your acid ("B-H") dissociates into B- and H+. Not that this would be very useful for particle accelerators...

Remember, the atmosphere is already "open to space at the top". To get any usable pressure difference, you would have to evacuate the shaft above the elevator (and use a very light-weight elevator). To loft the elevator all the way to the top, you would need to pressurize the shaft below it. Considerably.

Nothing wrong with your question: questions like yours sometimes force us to reconsider our assumptions, which can be a profitable thing to do Theories do not universally require math. For example, you might hypothesize that the world is round, and that therefore when you watch ships sailing away out to sea, the lower part of the ship will disappear from view before the top of the mast, as the ship sails past the horizon. No math required. (OK, perhaps we are dealing with geometry even here...) However, most scientific theories concern things about which we already have some understanding. If your theory is to succeed and be accepted, it will need to make predictions that (a) differ from the prevailing view, and (b) are confirmed by experiment. Sometimes those differences may be qualitative, but most of the time they're going to be quantitative, e.g., your theory predicts a measurement of X+0.00067 instead of the X given by currently-accepted theory. In such cases, mathematics are almost essential (and often, lots and lots of very detailed calculations) to prove your point. And then, of course, you get to cosmology and particle physics, where mathematics seems to drive the theories, for example, M-theory which seems to be based on elegant (but difficult) mathematical and topological arguments -- perhaps inevitable due to the difficulty of performing confirmatory experiments...

IIRC, sperm carrying an X chromosome have a different density from those carrying a Y chromosome, so that by careful ultracentrifugation you could separate them. Not sure the resulting mess would be viable, though On the other hand, you can apparently sort sperm by flow cytometry: still not 100% reliable, but supposedly >90%...

Mr. Skeptic has the right idea: it would probably be easier to clone the genes responsible for THC production into oaks, e.g., so that the THC was expressed in the leaves or acorns, rather than trying to get C. sativa to grow to oak-tree heights and support its own weight. How about cloning it into popcorn? Gives you the munchies and satisfies it at the same time

Some viruses, yes. Baculovirus provides an expression system commonly used for protein production in insect cells by biotech companies. Bacteriophage (viruses that infect bacteria) are commonly used as cloning vectors.

There is a science fiction story by David Brin ("The Giving Plague", available online in its entirety) about a blood-borne disease that alters human behavior -- influencing people to donate blood. Given the number of genes expressed only in the human brain, and the increasing number of small regulatory RNAs being discovered, I would say that it may even be likely that there are viruses (or other pathogens) that have a direct (but subtle, currently undetected) influence on human behavior. I assume that most people would opt for purging any such pathogen from our systems, in the name of restoring our "free will" to behave without the influence of the pathogen. However, to the extent that it results in a culture diverse from others, this may not be such a good idea. Diversity in outlook is a quantitative Good Thing, and reducing your culture to a clone of another just discards the value of having something different. Assuming that the behavior induced is not simply something like a willingness to be a suicide bomber, without an overwhelming compensatory advantage, I'd say keep the pathogen.

Good to hear (no pun intended) things looking better. I used to have a dentist named Dr. Payne, and a dermatologist named Dr. Pitts.

"Free Will" -- wasn't that a movie about a whale? Seriously, I would first define the concept as "the belief that we consciously control our thoughts and actions." Of course, that just escalates the question into "what is consciousness"? Sidestepping that, I'll just say that "I know it when I feel it" A great deal of our thinking occurs "below" the level of consciousness. For example, think about how you read: some part of your subconscious brain has to recognize the signals from your eyes as indicating a screen, and that there are letters on the screen, and that the letters form words that you recognize, and that you know the meanings of each of those words, and then that you understand the thought that was (hopefully) conveyed by those words. Your conscious mind is probably involved only at the last step (if then). Studies show that your brain (i.e., subconscious) makes an identification, or a choice or decision, milliseconds before you are consciously aware of it (and sometimes even reacts before you are consciously aware of what you are reacting to). So are you "there", or just along for the ride? Other studes show that you can consciously override the subconscious decision, at least in some cases. My speculation is that consciousness is more involved with memory: this is the function that turns our daily experience into a story, rather than a database of sensations. When you get home, and someone asks you "how was your day today?", you respond with an extemporaneous story (assuming you don't just answer "OK"), making a small history out of your personal experiences. Returning to the point: whether your decisions arise from your subconscious or your conscious thoughts, all arise from your brain, which has to obey the laws of chemistry and physics. Is that deterministic? Perhaps, although the brain is so complex that I suspect that as a system it is chaotic (or at least mathematically complex), and thus not predictable. Regardless of whether the decision originates in your conscious or unconscious thoughts, it is still yours.

Assuming that your transporter accurately copies everything (and setting aside the technological impossibility of this), including the state of all your neurons, then each copy that walks out of the transporter will be identical to you. You (original) step out of the machine, still on Earth, as if nothing had happened. For you (original), there is no trip at all. You (Venus) step out of the machine and immediately burst into flames (it's pretty hot there... ). You (Mars) step out of the machine into the airlock, with all your memories and thoughts intact: as far as you (Mars) can tell, you are the same person as you (original). The thoughts that you (Mars) have rapidly diverge from the thoughts that you (original) have, because you are in different environments, but for all practical purposes you would start out as being identical people. The fact that you start out identical does not mean that you would share consciousness in any way: no telepathy, no feeling sensations experienced by the other you, no switching from body to body. Now, what happens when you (Mars) teleports "back" to Earth?

For that you have to look at the backbone: all those phosphates. Phosphoric acid is pretty strong - much stronger than the bases are basic...

They're called "bases" because chemically they are basic (i.e., not acidic). Each has nitrogen atoms in the molecule that are capable of accepting H+ ions from water at neutral pH - that makes them bases by definition.

In the Renaissance, it was common for learned men (sorry, it was mainly men) to literally memorize entire books . Before the printing press, libraries contained mainly books for which only a very copies existed. The point of illuminating manuscripts was not just decoration, but to make each individual page memorable. If you encountered a good book in your travels, you would memorize it because chances were that you would never run across it again. Today, of course, we memorize little. We basically exteriorize our memories, in books and Wikipedia. The trick is to remember enough so that you know what to search for, and where to look it up. If I didn't have a blackberry, I would probably never get to a meeting on time. Speaking of which...

Here's a few more podcasts (I knew I'd forgotten some...): Cell Futures in Biotech Hmmmm... Krulwich on Science Science Friday Whitehead Institute Enjoy!

Well, the Merck Manual says that it may be temporary in the case of salicylates. I'm just guessing that ibuprofen acts the same as the salicylates. Your doctor should know for sure. Best of luck!