mistermack

I apologise in advance for duplicating the post of others. I haven't read back the whole thread, it's a biggy. I don't think we have a free will, no more than a leaf-cutter ant has a free will. The ant can go wherever it wants. Nobody polices it. But it's ordered by it's genes, through the brain that it inherited, and by the pheremones left by others. We are the same. I'm not free to enjoy a gay relationship. I was born straight. I can't enjoy a ginger biscuit. I disliked them right from the start. Those are obvious things, but so much of my decision making is less obvious, but still guided by what I inherited. Like my fear of heights or nervousness around dogs. Even posting on discussion forums, I can look back and see the old traits repeating themselves that I would rather not repeat. We are free within certain boundaries, that's all. If freedom is a black and white thing, either free or not free, then we definitely don't have free will. If it's shades of grey, then yes, we have a bit. As far as consciousness goes, you need it even if you don't have a free will. I have to be conscious to reject a ginger biscuit. Even if it's a sub-conscious or pre-ordained decision. The same goes for every other thing I do that is pre-programmed in my brain. It's like a computer. It can't do much when it's off, apart from retain the programs and data.

The Pope should have a serious think about that. Since AGW is intrinsically linked to the level of human population, something which he is doing his very best to boost to the maximum. So which is the greater sin, using a condom, or causing loads more warming?

I think butterflies and moths are the best animals to study, to illustrate the different problems and advantages of the different body types. Caterpillars are ideal eating machines. They are just there to eat what is close by. With their soft relatively homogeneous bodies, they are not designed to travel far and wide to find a food source or mate. But a butterfly with it's stiff levers and strong but light wing material can fly huge distances, both to find a mate, and find an ideal food source for it's caterpillars, after it's eggs hatch. The same goes for a vast range of insects. So they manage to benefit from the advantages of both body plans in one lifetime, and to negate the disadvantages. That's why there are so many of them.

HI Eclipse, great links. I agree about the scale. However, just because you can't do it all, doesn't mean you should not bother. For instance, it's often said that you need XXX number of wind turbines, to replace fossil carbon. That's true, but it's not a reason for not using SOME wind turbines. I'm reacting to what I think is a loony idea, of sequestering CO2 underground. I think any money spent in that direction would be better spent on long-lived trees, that's all. You would fix more carbon for your money, and create a growing asset, not a liability.

In the end, the question "why hasn't evolution done X" is a particularly futile one. It's like starting a rock rolling down a hill, and asking "why didn't it hit this tree?" at the bottom. Or "why didn't I win the lottery?" If it all started again, the results of evolution would look dramatically different in the same timeframe. Yes, it's a definite process, but it's also hugely random. That's why.

Yeh. I think Churchill was really just reflecting the general speculation that was common at the time. If anything, people were MORE open to the existence of alien life back then. As the Orson Wells broadcast illustrates. Which is ironic, because now we know far more about the existence of exo-planets, and yet fewer of the public would accept the likelihood of alien life. Personally, I'm convince that the galaxy is teeming with life, but i'm not so sure about intelligent forms, capable of much more than what Chimpanzees can do. My suspicion is that we humans really are a freak occurrence, and intelligence will generally hit a brick wall, wherever it arises.

"How do you find the equilibrium temperature for earth given an input energy?" I think the best way is to look at the temperature record in the ice-cores of Antarctica and compare it to the best calculations of historical solar output. And I believe that has been done in peer-reviewed studies many times over.

I think there is every chance that if aliens ever came to Earth, it would be by way of un"manned" machines. After all, what kind of machines will we have in the year 3,000 ? And why would you send humans on such incredibly long journeys for no reward of any kind? There's every chance that by the year 3,000 we will be able to produce machines that are "superior" to humans. And you will be able to shut them down for a thousand years, and wake them up on arrival at the target. That's the sort of stuff I would expect to find, if aliens had bothered with coming our way.

Serious people WERE open to the notion of extra-terrestrial life in those days. Wasn't there serious discussion given to the existence of canals on the surface of Mars, well before Churchill was writing this stuff?

I would say that the first nuclear bomb test changed the world for all time as well. Maybe not for the better, but it was definitely the most influential experiment of the last century.

Yes, I'm sure that's right. I don't think it affects the topic particularly though. We don't know that EM is the most fundamental level of matter or energy. An EM clock might be a derivative of some even more fundamental processes that we are nowhere near discovering. But it all works at our present level of knowledge.

Microwave background radiation discovery.

Having looked at length contraction, there appears to be no reason why it should not occur in this hypothetical sound-clock scenario, IF you actually were able to use sound clocks. The length contraction arises as a result of time dilation, so observers using sound clocks in different reference frames will measure different lengths for the same object.

Janus, thanks for that. I found it very interesting. Forty five years ago, I would have sat down and dashed off something similar in no time, but no way could I today, I avoid maths like the plague these days. Just a few comments. Firstly, I'm not actually arguing for an aether. Back in the thread, I just made a comment that you could do the same for sound waves, (or something like that) and the discussion just rolled on from there. Secondly, you say that a light clock would also run at different speeds, for different angles, if it were not for length contraction. So it's length contraction that makes the difference between the light example and the sound example. Well, the answer might be that the sound clock we are talking about is not a true sound clock. Yes, the pings are the result of sound waves travelling. But the rest of the clock is made of material OTHER than sound waves. If the clock was ENTIRELY made of sound waves (however that might happen) then perhaps you would get a similar length contraction to the light clock. So in comparing the two clocks, we're not actually comparing like for like. For the last bit, whether it's movement through nothing, or movement through a medium, the result is the same. It's the combination of time dilation and length contraction that make the result the same for all observers.

Not at all. You are not responding to what I wrote. You're responding to a cut down version. If you look at MY post, it's made perfectly clear that I'm saying that we have no clocks that are not affected by the time dilation of SR. In the case of a sound clock, you have access to an external clock not affected by the motion through the medium. In the case of measuring the speed of light, there is no clock unaffected by time dilation. So here's a question for you : IF there was such a thing as a clock, that was not affected by time dilation, would all observers using it measure the same figure for the speed of light?

Strange, all three of your comments are either wrong, or miss the point entirely. Firstly, clocks aligned at different angles to the motion do NOT travel through the medium at different speeds. Secondly and thirdly, your posts contradict each other.

You've asserted that they would tick at different rates, but you haven't given any evidence for that. It might be right, but it also might not. As far as the second goes, an observer travelling with the clock could only note that it ticks at different rates, if he had a different clock to compare with it. When it comes to measuring the speed of light, we have no other clocks. Time dilation occurs for everything. Which igoes back to my original point. All observers measure the same value for the speed of light, because they use clocks that slow, with their relation to the speed of light.

Quite right. So using a sound clock to measure the speed of sound, is having the same effect as using a light clock to measure the speed of light.

The point is that highway speed is a tiny fraction of the speed of light. If your sound clock was moving at a similar tiny fraction of the speed of sound, then the time dilation would be equally minimal. If your atomic clock was travelling at one tenth the speed of light ( like highway speed is one tenth the speed of sound ), then you would expect some significant affect on the atomic clock.

Nobody's talking about a crappy clock. Or are you forgetting that atomic clocks slow as their velocity increases? A sound clock would definitely slow, as it's velocity in the medium increased. And would be stopped altogether, if the clock reached the speed of sound. Doesn't that remind you of anything?

That's an interesting point. But, are you assuming that the reflecting target is stationary? I was talking about a clock that co-moved with the observer in it's entirety. So the sender and target are moving through stationary air with the same velocity. In practice, they would be physically attached.

Well the answer is obvious. There are some advantages to having a skeleton. It seems you don't like the obvious answer, but that doesn't make it wrong. If you have an idea of some non-obvious answer, why not share it? There are plenty of animals that have more homogeneous bodies. Like grubs maggots and caterpillars. Billions of them. They are suited to their own niches. And have various ways of keeping going, such as being inaccessible, or being poisonous, or having enormous fertility. They don't survive just on one aspect, such as body form. Nothing does. Evolution works on variety. No single body form dominates. If you go on simple numbers, then grubs, maggots and caterpillars are probably as numerous as other types. But then they go the other way, with an exoskeleton, if they undergo metamorphism. The one form is successful in finding food, the other in mobility which helps finding a mate.

Strange, you completely missed my point. The speed of sound is NOT independent of the observer's speed through the medium. I didn't say it was. It's always the same, relative to the medium. (in standard conditions) BUT, if the observer's clock operated using sound, ( for example by pinging a sound to a target and measuring the time for the return ping ) then the observer's clock would slow with velocity, and they would consequently always get the same value for the speed of sound, regardless of velocity.

Can an infinitely thin plate exist? Can a massive particle have zero dimensions? Or can a two-dimensional plate actually have any mass, or exist at all? ( I don't know, I'm just asking )

The big assumption is that the permitivity and permeability of free space are always the same, everywhere. Which seems to be true. The same doesn't apply to sound waves in air or water, as the equivalent properties vary with temperature etc. Is the permeability and permittivity of free space dependent on the velocity of whoever measures it? That would seem likely, EXCEPT that the velocity of the observer also affects his clock. So, because of time dilation, an observer will always measure the same values for permittivity and permeability..And hence will always get the same figure for the speed of light.