Fred56

Please stop trying to confuse things. You said it first' date=' so explain why you said it. ...remember? You and me both. I would say a course in Logic and possibly a review of the meanings of 'transitive' and 'commutative' might help... One more time, just so we're clear: Photons have a mass equivalent, as Einstein demonstrated when explaining the photoelectric effect (among other papers he wrote). Photons have no intrinsic mass, but because they are (pure) energy, they are therefore equivalent to some mass. [/me]

Cheers for those links. It's been a while since I looked all that closely at anatomy and so on --the Bio terminology might need a review on my part. Interesting that the 2nd article uses video cameras as an analogy. The first one looks like a good overview or intro to what's happening in this field (btw how old is the 1st one?) What I'm after is any studies (can't find much) about what effect modern image and colour processing could have on discrimination. Maybe I'll need to do the study myself, or something (I asked a lecturer the other day about doing an Optometry course, he said "sure, but it won't count towards the qual.") I read that post (here) by that Honours stud. who asked for some participation in a colour experiment, and wondered about what difference there might be between colours on a screen, and 'natural' colours. Maybe someone already knows...

Isn't stealing someones work exercising a "right to copy", then, you would say?

What about image 'compression', using JPEG or MPEG which discards certain visual information, which the algorithm decides isn't important. This possibly applies to MP3 too, because it does a similar thing with sound. JPEG, MPEG and so on are 'lossy' algorithms, so does it affect our perception at all?

Imagine if Gandalf the Grey had stood with his staff on the bridge at Khazad Dum, and spake thus unto the Balrog: "No admittance to public. I am authorised to inform you as employee of the Secret Fire and administrator of the flame of Anor, that you must return and exit via public access. No admittance! Authorised personnel only."

To get the ball rolling, I'll post stuff from another forum where a bunch of other dudes has tried to figure this out. I got into a stoush with someone who appears to be stuck on the idea that we can't say it's even meaningful, and is no use in any definition (even though he then seems to be quite happy to use purposeful behaviour as a distinctive, and observable phenomenon). I can't figure out why he can't see what the problem is with the approach he is using, so maybe some bright spark can shed a bit of light:

K, I'll have a look at this, but my first q is: say the cat isn't given a dose of LSD, now explain how what happened in the cat's subjective brain wasn't something like what a dose of LSD would do?

How good is the visual system in humans at discriminating colour shades or hues (millions)? What difference does it make if they are processed or compressed images (of natural colours), to the discrimination?

What differences might a brain discriminate between natural pigments and JPEG copies of those same 'hues' on a screen. Or what difference the particular type of screen -plasma or lcd or analog might also make?

Just a thought. Lots of color we see is from compressed or otherwise processed images. So what differences might there be between her experiment and natural colours, or pigments in a painting (or the compressed copy of the 'control' colours)?

Religion is arguably an institution that gets hijacked (because it is an institution of 'believers' who have a leader or two ready-made), often by men with quite different goals than 'peace and love everywhere'. Guatama Buddha left strict instructions not to ever build or carve any likeness or image of himself. Christ was also quite plain about this issue. Hindu traditions and the overall religious theme (which has evolved over at least as long as European 'traditions'), I think represent almost the pantheon of religious themes, but the (evolved) undercurrent or tradition has a strong sense of the same, individual sense of godhood that are common to the others (if you're still with me here).

Is the notion of copyright, of exclusive authorship and ownership (especially of any financial benefit), an anachronism? Is this idea doomed to the scrap-heap of publishing history? Who hasn't 'helped themselves' (a legally proscribed action) to 'copyrighted' material that you know, you know? [mod note: moved out of medical to general discussion]

I don't think an appeal to the spirit world is going to help here. Sorry, this makes little sense to me, or to the relevant question (why don't photons have a mass equivalent?). Are you avoiding the required substantiation of your claim which is the exact opposite of Albert Einstein's conclusion? (JaKiri: Energy is not photons, photons don't have a "mass equivilent") sic. Then, in your last post, we see: "You can't be denying that the photon has energy, so this is consistent." which disagrees totally with your earlier post: "Energy is not photons". Are you saying a photon "carries energy around", in some container? That a photon is "something" which can have energy? Einstein said (some time ago): "It followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing —a somewhat unfamiliar conception for the average mind. Furthermore, the equation E = mc², in which energy is put equal to mass, multiplied by the square of the velocity of light, showed that very small amounts of mass may be converted into a very large amount of energy and vice versa." You seem to understand this, but then go on to claim, apparently, that he got it all wrong. As to the photoelectric question (which is from a grad. Physics exam), why are you asking: "What part of that question requires that the photon has a mass (or equivilent quantity)?" where does the question ask about the mass of anything? Except you know (I hope) that electrons have mass... Time to ante up, dude. Please explain why photons have no mass equivalent, and why photons "are not energy". P.S. you did notice I used the "wrong" form of the constant -Dirac's version instead of Planck's- well done.

The expansion (recession) of galaxies has to overcome any gravitational field (which isn't so hard), and atoms aren't expanding, nor is our planet, nor are we (because an atom is something that is bound by stronger forces, EM and quarks, the planet is gravitationally bound together, and we are in the gravitational 'well')... You can analyse matter as particles, but also as waves (that interfere like other kinds of waves).

I'd be 'happy' to discuss his belief system with him (and try to get under the epidermal layer simultaneously). Unless he's a rhino in disguise...

Shouldn't we be asking if chickens are commutative (or transitive)? And eggs, how do those funny sort of round things turn into chickens, is what I would like to know.

Bacteria and other prokaryotes do seem to have some evolutionary advantage over us more developed and complex critters, and the prokaryotes outnumber and outweigh every other kind of life by a 'large amount'. An extinction 'event' is more precarious for lifeforms like us, bacteria can live in environments that we can't (even miles and miles underground, and up in the atmosphere), and would have a better chance of survival. Also they evolve a lot quicker. Other mammals have a lot more to worry about from the threat of human dominance than any teeny-tiny bugs do. We aren't as 'overwhelming' as we sometimes think we are, for a kick-off. An example might be something like an oil spill. This is generally pretty devastating for many forms of life (birds, mammals, fish, bivalves, marine flora), but some "bugs" tuck right in (dinner is served). The concept of (us) dealing to the world of prokaryotes is a bit far-fetched (but we might invent some kind of universal super-bug that proves to be a problem for them, so they would then need to evolve a solution to deal with it, which is quite a probable or even inevitable outcome).

A disaster would have a local effect (unless it was real big, say a supervolcano, which is still a theory, isn't it?). So it's down to any survivors. Obviously, there were some of these (in our case).

I believe the current theories of Homo extinction are focused on climate change as being the proximate cause. The end of an ice age usually means a lot of this occurs, and there have been a few ice ages. And I just realised I made a mistake in another post about the Holocene being the onset of ice-ages (instead of the latest one). They started when the continents got to roughly where they are now, the Cenozoic, the start of which geologic period is marked by the KT boundary, ~65m yrs ago. But we or our predecessors weren't around until the Miocene , I think.

Dominance is a vague target, which depends on what you're describing. We are the dominant vertebrate mammal, currently (which means we are much more efficient at getting resources, at dealing with competing species, ...). Some bacteria are dominant in the world of prokaryotes (but it depends where you look), which we have little chance of dominating (but we like to think we can get rid of the little buggers).

I read somewhere that Homo sapiens was initially a small group of survivors at the edge of the African savannah (~10^6 yrs ago), following major climate change and desertification. Lots of other Homo species disappeared, due to large changes back in the day (the end of the Pleistocene?). The Holocene is the current interglacial. Also there is evidence that modern humans are descended from Asian ancestors (who left Africa much earlier). Neanderthals went extinct before the interglacial, by about 20k yrs.

Apparently so.

There is a way of describing momentum as fundamental to (inertial) mass. Electrons have a mass (vector), so if they 'change' in an inertial field, they acquire energy (but this is all observation, electrons don't acquire, or change, we just 'see' them do this). The energy acquired has an equivalent (measurable in EM terms), but we don't usually define or describe it this way.

The last part of this sentence is absolutely correct, photons (and everything else), never get to stop and have a rest. But why can't you say [math] E = \hbar\nu [/math], and the equivalent mass is [math] E/c^2 = \hbar\nu/c^2 [/math], which is what your objection appears to be? Notice the term 'm' does not appear... And why do you claim: 'Energy is not photons, photons don't have a "mass equiv[a]lent"'. This statement is clearly the opposite of Einstein's. So are you going to have a crack at the (exam) question I posted? Would you like a definition of "work-function of a metal"?

At present, the map of the cortex (never mind -sorry about that pun- the rest of the brain anatomy) isn't exactly complete. And we have only rudimentary understanding of how the cortex functions. We still have no good understanding of how any sensory input is encoded, or processed (beyond watching activity using fMRI, or PET), so we certainly need to find out a lot more. And we need the technology that will get us "in" there. This sounds, to me, like 'electronic', or equivalent, devices that will be interfaced directly. This is how we will get whatever is happening in there onto some kind of blackboard, and I also think this is probably inevitable (and it will allow the converse, a brain communicating with a machine directly -like by thinking, something available right now). Current IS models are somewhere along the path, but where exactly? What sort of changes will be brought by the eventual introduction of brain/machine direct interfaces? As long as you aren't too upset about having to plug yourself in every now and then.