Hydroelectric power sort of depends on the sun to evaporate the water involved (that's where the water gets the potential energy it has, the sun does the initial work against gravity, and then later we harvest that energy).
Correct - the sun is the source of the energy.
I'm not sure about tidal, but I think the sun is at least involved in the tides.
No, it's the moon. The source was the supernova explosion that gave rise to the solar system, and kinetic/potential energy to the earth-moon system.
The winds also get their energy primarily from the sun.
Correct.
Geothermal is probably not dependent on the sun.
Correct - this time the energy comes from heating caused by radioactive decay of elements (and their decay products) created in the supernova explosion.
I saw Hamlet recently and one of the things that struck me was how strange it was to listen to dialogue which requires a lot of attention, and then to suddenly hear a "well-known-phrase-or-saying" that you'd heard many times before. Quite distracting in fact.
If the strong survive and the weak die off, it makes sense that the strong would survive long enough to evolve. Shouldn't there be MORE of these fossils? Why do we only find the dead end?
I'm not an expert but surely fossils of direct ancestors of current species should be exceedingly rare? This is exactly what we find.
Consider 2 eras A (early) and B (late) separated by a considerable time in evolution, but with approximately the same number of species in each, lets say 1 million. Now to be guaranteed that every fossil found at time B is a direct ancestor, no species from time A until time B can have given rise to more than one other species, and also no species can have become extinct. i.e. we would have a tree with no branches.
However we know that there are many branches is evolution, and this is what we should expect as some species are more adaptable and give rise to many other species. So one species may give rise to 2 others, which in turn give rise to 2 others and so on, yet another may become extinct. Go back far enough and you should expect the vast majority of the fossils you find to be from species that are on evolutionary dead-ends - unfortunately, fossilisation does not favour those species that continue to evolve and survive.
I'd be interested to know what proportion of species alive at time A were not on evolutionary dead-ends. Out of a million species it wouldn't be surprising if that number was of the order of 100 or less for sufficiently large timescales between A and B. As an example we know, of all the dinosaur species that existed that very few, the ancestors of all birds, have passed their genes onto species that exist today (10,000+).
Even when timescales are quite short (a few million years), you'll find most species do not go on to survive. For example, humans are the one remaining species in the homo genus of which we know of about 15 other species, none of which were ancestors.
So we should expect most fossils we find to have no living descendants. And even if we do find a direct ancestor, there are difficulties identifying it as an ancestor anyway - perhaps the fish that eventually gave rise to you and me exists in a museum already?
One of EFFs goals is personal privacy. Encryption is based on prime numbers, the larger the prime, the more secure it is. Having an insanely large prime would take nearly forever to crack the encrypted message.
I'm not convinced using one of the 48 known Mersenne primes as the basis for a new encryption algorithm is going to be particularly secure!
If we simply focussed on running the existing primes through 2^n-1, we'd find every prine through a few billion didgits in a couple of years.
Unfortunately it's not that simple. Not all primes are of the form 2^n-1, and numbers of that form are not necessarily prime.
Currently there's no efficient algorithm for generating a list of primes in sequence and your estimate of a couple of years is way off (as in "many many lifetimes of the universe way off"). Even testing whether a number is prime is not efficient.
The reason work is concentrated on Mersenne primes is that there there is a particularly fast test for primality for numbers of the form 2^n-1
You are making this more complicated than it needs to be.
Let's assume a population of 4 thousand if you like. I hope you'll agree there are 4 equally likely possibilities:
1) M - M 1000
2) M - F 1000
3) F - M 1000
4) F - F 1000
Then we apply the random selection and the further knowledge we are given, i.e. at least one of the children is a girl. This discounts M - M and we can deduce the probability of F - F is 1000/3000.
Also from the table above we can work out if we know the eldest is F then the chance of the other being a girl is 1/2 and if we know the youngest is F then the chance of the other being a girl is also 1/2.
And hence we have four options. Either we've got F/[M] or F/[F] if we've learned the first one, or we have [F]/F or [M]/F if we've learned the second one. We don't know which to use, because we don't know which we've learned, but luckily they have the same 50/50 odds.
The mistake here is you've included the F/F set twice because you are treating F/[F] and [F]/F as different sets, which they are not. Consider what you're saying here, that p([F]/F or F/[F]) is twice p(F/M) and twice p(M/F). Or another way of looking at it is the probability of the eldest being F is 75% if you consider F/[M], F/[F], [F]/F and [M]/F to be equally likely (25%), which is incorrect.
It's only when the original choice of the family, in some way, depended on one of the children being female that the probability changes to 1/3. Like if you go around selecting families with one daughter, which means there's a 2/3 chance the other is a son.
For the purpose of this probability calculation, the knowledge we have "at least one daughter" is equivalent to "randomly select from families with at least one girl". In both cases we start off with the same information on which to base the calculation. I'm interested to know why you see there's a difference.
Incidentally, if the question was phrased something like "a family was chosen at random, and I met just one of the children, who was a girl", you will get the 50% probability you mention, but this cannot be deduced from the original question . "First child I met was a girl" implies "at least one daughter" but the reverse is not true.
The GP is correct in this case as they did not specify whether a particular child was a girl. All we know is that at least one is a girl.
You are correct that "telling us the gender of a child tells us nothing about the other one", but we've not been told which of the children is a girl so this this is not relevant here. All we know is that we have 3 equally likely possibilities - M/F, F/M and F/F.
So in this example, these questions mean the same thing:
A family with two children is chosen at random from a large population. If I tell you only that they have at least one daughter, what is the probability that both children are girls?
If we pick out two parents who have at least one girl, what are the odds that their other child is a girl?
What is relevant is how the questioner knows that there is at least one daughter e.g. by asking the parents "Is your eldest a girl?" or "do you have any daughters?" gives probabilities of 0.5 and 1/3 respectively, but the way the question was phrased implies the latter.
In that case the probability will be "close to 50%" assuming Mary is a reasonably rare name amongst girls.
Assume 10% of girls are named Mary, and a sample size of 2000
Oldest child - Youngest
Boy - Boy 500
Boy - Mary 50
Boy - Girl not mary 450
Mary - Boy 50
Mary - Mary 5
Mary - Girl not mary 45
Girl not Mary - Boy 450
Girl not mary - mary 45
Girl not mary - girl not mary 405
Probability of 2 girls assuming at least one is called Mary = (5 + 45 + 45 + 405)/(2000 - 500 - 450) = 500/1050
This is still not 50% but p(2 girls) does approach 50% as p(girls name is Mary) approaches 0
Your second example is only true if you add an additional assumption: that a family never has 2 children with the same name, in which case your question is better expressed as "If I tell you only that they have exactly one child named Mary, what is the probability that both children are girls?". In this case the probability is 50% as you point out.
However, if a family can have 2 children with the same name the probability will depend on the proportion of Marys amongst girls. For example if all girls are called Mary, your second question *is* the same as the first one and the probability is 1/3. If Mary is a rare name (as in the real world), the probability will be slightly less than 50%.
Certain employees produce chunks of data - whether words or software code - that later pop up in other messages. The people copied most often, Cataphora concludes, are thought leaders.
In my experience the code that is discussed in emails is just as likely to be because it is bad as it is because it is good and I'm sure the examples at http://thedailywtf.com/ often "pop up in other messages".
Good managers already know the value of their staff by talking to them, talking to their colleagues and assessing their work. If a manager has to resort to analytics like this at least a corporation knows where their management problems lie.
As other replies have stated it depends on the pressure and at about 0.15 atm or less, it will be a gas at this temperature.
However, the triple-point of methane is at about 0.1 atm which means that methane cannot exist in liquid form anyway given the very low atmospheric pressure on Pluto (1/100,000 atm or less). If you reduce the temperature by just a few degrees the gaseous methane will deposit as a solid, without passing through the liquid phase and in fact, solid methane is found on the surface of pluto.
Clearly these subs were tracking the 2 satellites that collided last week http://science.slashdot.org/article.pl?sid=09/02/11/2318226. The six day delay can be explained by the difference in speed of a nuclear sub compared to a satellite.
_My_ problem however is: why did mutation _B_ happen and get selected by natural selection? And _if_ it causes a harmful trait, why didn't natural selection eliminate it yet?
I think the argument goes something like this:
Mutation B (tail-size preference) occurs randomly. Initially this provides neither a benefit or a hindrance.
A male individual with mutation A (larger tail size) appears. This male will chosen over males without the mutation by females with mutation B, and has an equal chance of being chosen by females without mutation B. So long as the larger tail size is not a hindrance at this stage, there is now a selection pressure for larger tails.
Being in a minority, males with larger tails have less male competition for females with mutation B than for those who don't have a preference, so tend to mate with females who have a preference. This means their offspring have a good chance of having genes for both the long-tail male trait, and the long-tail preference female trait. Mutations A and B now tend to appear together in individuals.
So now we have a situation where long-tailed peacocks are likely to pass on the long-tail preference gene and where they do averagely well with non-choosy females and better than average with choosy females, so the long-tail preference gene increases in the population in general.
Which means peacocks with short tails do poorly, until all members of the population eventually have both the long-tail gene and the long-tail preference gene. And there's still selection pressure for even longer tails, so average tail-length tends to increase until the benefits of having a long tail are outweighed by the disadvantages in terms of defense etc.
Bingo. That's the whole point: if it was a handicap for the species, it should have happened. That's the basic prediction of natural selection.
I think this is the basis for what I see as your mis-understandings regarding evolution. Evolution does not produce species which are optimally adapted to the environment in which they find themselves - natural selection can only work on the genes that already exist, and we need to remember that new genes are created in a random process. Over time you might expect deleterious traits to disappear but this can't happen unless there's a mutation (or a new/amended gene introduced through breeding).
You've also managed to underestimate the importance of sexual selection in evolution. Natural selection concerns the ability of genes to be passed on to following generations. Genes will only be passed on if the organism both survives to sexual maturity (i.e. is sufficiently adapted to the environment) and manages to mate successfully. The latter provides a _very_ strong selection pressure regarding genes affecting sexual attractiveness and behaviour.
You may be right that the peacock's tail provides other advantages other than sexual attractiveness, but even if it doesn't and it in fact makes the peacock less adapted to it's environment, its advantages in helping it reproduce can be enough to ensure it's genes are passed on rather than those of peacocks with smaller tails.
To explain why the gene doesn't disappear from the population you need to consider the long-term mating success of the lineage without the genes. And you need to take into account there are 2 traits here - there are genes that cause males to have large tails, and others that cause females to prefer males with large tails. The argument is too complex for me to remember accurately, but it's in one of Richard Dawkins books I think.
If a smaller tail were an advantage, then their kids live longer and get more chances to reproduce. With each other if nobody else wants them. Repeat a few generations, and that trait will be on its way to extinction.
They may have more chances to reproduce but you need to consider they're in a population of females that predominantly prefer large tails. And they themselves still carry the large tail preference gene.
Nobody has ever used the (non)existence of dinosaurs to push public policy that handicaps our society's productiveness while giving less scrupulous countries the ability to gain yet another competitive edge on us.
My response was not anything to do with the direction public policy should take, but with the science behind the predictions of climate change - I was merely highlighting that science often uses indirect evidence to formulate theories and this in no way means the science is not valid. IMO it's important the scientific research should be independent of the possible implications of any conclusion, one way or another.
The post to which I responded used emotive and unhelpful language to criticize a lot of good science - the debate would benefit from people concentrating more on the science sometimes, rather than the politics surrounding it.
Fantastic demands require fantastic proof.
So let's help the scientists do some "fantastic science" so we know more about the situation we're in, before knocking them. Unfortunately, we will never have access to direct measurements of historical climate so the more we refine these indirect measurement techniques the better. However, it's unlikely that there will ever be "proof" for those people who think indirect climate measurements should be ignored by climate scientists.
I wouldn't have thought climate scientists would have much of a problem with climate proxy indicators being referred to as indirect evidence so there's no need for your use of the pejorative term "euphemism" there.
And if you think "circumstantial evidence" includes race, sex, and religion in a court of law, you clearly don't have an understanding of this term either.
Read up a bit on the science involved and you might be surprised to find some of these proxy indicators are little different than using the existence of fossils to infer the presence of dinosaurs in prehistory.
Or perhaps you don't believe in dinosaurs?
This project appears to be good science, whatever your views on climate change - it's recognizing there is a limit to the accuracy of what we currently use as proxy indicators, but by comparing proxy indicator predictions against actual measurements, it hopes to refine our use of these indirect measurements so we can use them to get a clearer idea of the causes of current climate trends.
To people who don't know about UK politics this post might imply that Scotland is not governed by the British (Westminster) government. Scotland still is, though many powers have been devolved to the Scottish parliament.
If the Conservatives form the next British government, Scotland will still be affected.
Exceptions include information other that that covered by the Official Secrets Act.
There are also a whole lot of exemptions, such as data that is commercially sensitive, related to criminal investigations or where disclosure would contravene the Data Protection Act etc. When a request is refused the reason for the exemption must be given to the requester.
In practise the Act has meant a lot of information is now public where it wouldn't have been before.
The problem is that evolution is a very slow process. This has not been a problem in the past because environments tend to change slowly too, allowing species to adapt rather than become extinct. Many species don't adapt and become extinct, but in prehistoric times the rate that new species were created was faster than the rate at which they went extinct.
Man has the unique ability to change the environment to suit ourselves, it's what we are really good at, and this is one of the reasons why we are seeing so many extinctions at present, particularly in the last few hundred years or so.
It's not arrogance to realize our major role in the high current rate of extinction - other "natural" causes pale into significance compared to the effect man has. The only sign of hope (assuming bio-diversity is seen as a good thing) is that we're also intelligent enough to realize the effect we're having. I'm not so hopeful whether we'll be able to control our natural instincts and preserve environments rather than exploit them and move on. We might be able to do this for the next hundred years or so, but what about the next thousand or ten thousand years?
Mathematics provides a lot of the tools that show that evolution is not surprising, can explain "holes" in the fossil record etc. For example probability theory shows it would be unlikely for there to be no holes in the fossil record give the low probability that any individual organism is fossilised, let alone the low probability that we find it.
Mathematics can also help us understand why it is possible for single-celled organisms to eventually evolve into the complex life we see today - how many ancestors do you think a human has since multi-celled organisms appeared? It's a lot!! Each generation provides opportunities for random mutation and natural selection - add them all up and most mathematicians should see why evolution creates the diversity of life we have today.
We'll probably never have direct evidence of how DNA appeared but you might like to think about the following question: given a planet with the same general environment as the earth, a source of heat, and the same elemental composition, use your knowlededge of math and chemistry (particularly carbon-chemistry) to predict the nature of the most complex molecules that exist after 2 billion years or so. Can you really be sure that with such a large experiment and such long timescales, you wouldn't end up with a molecule that can self-replicate?
And once you have a molecule that can do that, there's no stopping it - it can continue to evolve so that it can begin to affect it's local environment to make it easier to survive and replicate etc etc. Eventually you have DNA.
If a mathematician has a problem grasping the theory of evolution it's due to their lack of knowledge about chemistry, not because the math doesn't add up.
> So the "Proof" of global warming is basically that we have no better theory?
I'm not sure what you mean by Proof of global warming. Global warming is a fact - there are measurements that show this clearly.
> We are being told that Global temperatures have gone up by fractions of a degree.
About 0.5 Celsius increase in 40 years I think. It doesn't sound like much but to climate scientists it's a big deal. It's a lot of extra heat in the atmosphere.
> I would be amazed if they could actually get all that data together without the margin of error being at least fractions of a degree.
Accurate readings of temperature have been possible for over a hundred years now and the margin of error estimating temperatures 1000 years ago using indirect means is only +/- 0.5 degrees. Statistical analysis of actual measurements means we can be effectively certain that global warming is real.
> I can have 3 different digital thermometers in different places in my yard and they will all read different.
Try an experiment then - take readings from each thermometer over a period of time and plot a graph of temperature against time for each of them. See how they track each other? Now consider doing this for 100 years in thousands of places around the world, analyse the results statistically and you'll see a similar pattern. They won't track each other as well as the thermometers in your back yard due to weather being different in different places but you will see a clear trend.
> Going back 100 years they didn't have digital thermometers.
They had mercury thermometers - a technology still used around the world today to decide whether to rush children to A&E. Sometimes it's surprising how good older measurements were (e.g. measurements taken in the same locality but by different people agree very well).
> Temperatures in Cities are warmer than outside cities.
This is true and you will find temperatures in urban areas that were once rural have increased significantly. Of course scientists are aware of this effect, and take this into account e.g. by discarding measurements from existing urban areas.
> Global warming appears to me to be science with an agenda behind it. With something as big and as complex as this, I think you could try to have the numbers say just about whatever you want them to say.
I think there are people on both sides who have an agenda and this doesn't help things. However, when you look at the data from a scientific viewpoint it clearly shows that global warming is real. There's really little doubt about this and even groups opposed to the scientific consensus of man-made warming now concede this fact.
The debate has moved on now - it's not whether global warming is happening, but whether its causes are man-made. And the majority of scientists feel this also is pretty much confirmed now and the debate should be about what we can do about it.
> The problem is the AGW guys shouting that the argument is over and that there's a consensus and everybody should just shut it and get in line. To hell with that. That's not science, but rather a nasty form of political orthodoxy.
The GP post concerned statistical fluctuations in mean temperatures - to me this is science.
You raise possible economic and human consequences of taking steps to deal with a perceived problem - to me this is political.
I think your post demonstrates how easy it is for the discussions on climate science to turn into political discussions. Somehow we have to keep these separate, as political considerations should never be a factor in determining scientific truth.
There is a discussion to be had regarding whether we should be making wide-ranging economic changes based on theories that are x% likely to be correct, but the consequence of these changes (or the impact of not taking action) should not have an impact on the science, other than to act as a guide to decision-makers where best to allocate research funds.
Slashdot Mirror
Hydroelectric power sort of depends on the sun to evaporate the water involved (that's where the water gets the potential energy it has, the sun does the initial work against gravity, and then later we harvest that energy).
Correct - the sun is the source of the energy.
I'm not sure about tidal, but I think the sun is at least involved in the tides.
No, it's the moon. The source was the supernova explosion that gave rise to the solar system, and kinetic/potential energy to the earth-moon system.
The winds also get their energy primarily from the sun.
Correct.
Geothermal is probably not dependent on the sun.
Correct - this time the energy comes from heating caused by radioactive decay of elements (and their decay products) created in the supernova explosion.
The GP is correct - it's the bacteria in root nodules of nitrogen-fixating plants that are do the fixing, not the cells of the plant themselves.
I saw Hamlet recently and one of the things that struck me was how strange it was to listen to dialogue which requires a lot of attention, and then to suddenly hear a "well-known-phrase-or-saying" that you'd heard many times before. Quite distracting in fact.
As for Richard III, most people haven't seen it.
Yeah, it was deservedly canned by the critics so Shakespeare never got to do the follow-up, Richard IV.
If the strong survive and the weak die off, it makes sense that the strong would survive long enough to evolve. Shouldn't there be MORE of these fossils? Why do we only find the dead end?
I'm not an expert but surely fossils of direct ancestors of current species should be exceedingly rare? This is exactly what we find.
Consider 2 eras A (early) and B (late) separated by a considerable time in evolution, but with approximately the same number of species in each, lets say 1 million. Now to be guaranteed that every fossil found at time B is a direct ancestor, no species from time A until time B can have given rise to more than one other species, and also no species can have become extinct. i.e. we would have a tree with no branches.
However we know that there are many branches is evolution, and this is what we should expect as some species are more adaptable and give rise to many other species. So one species may give rise to 2 others, which in turn give rise to 2 others and so on, yet another may become extinct. Go back far enough and you should expect the vast majority of the fossils you find to be from species that are on evolutionary dead-ends - unfortunately, fossilisation does not favour those species that continue to evolve and survive.
I'd be interested to know what proportion of species alive at time A were not on evolutionary dead-ends. Out of a million species it wouldn't be surprising if that number was of the order of 100 or less for sufficiently large timescales between A and B. As an example we know, of all the dinosaur species that existed that very few, the ancestors of all birds, have passed their genes onto species that exist today (10,000+).
Even when timescales are quite short (a few million years), you'll find most species do not go on to survive. For example, humans are the one remaining species in the homo genus of which we know of about 15 other species, none of which were ancestors.
So we should expect most fossils we find to have no living descendants. And even if we do find a direct ancestor, there are difficulties identifying it as an ancestor anyway - perhaps the fish that eventually gave rise to you and me exists in a museum already?
One of EFFs goals is personal privacy. Encryption is based on prime numbers, the larger the prime, the more secure it is. Having an insanely large prime would take nearly forever to crack the encrypted message.
I'm not convinced using one of the 48 known Mersenne primes as the basis for a new encryption algorithm is going to be particularly secure!
If we simply focussed on running the existing primes through 2^n-1, we'd find every prine through a few billion didgits in a couple of years.
Unfortunately it's not that simple. Not all primes are of the form 2^n-1, and numbers of that form are not necessarily prime.
Currently there's no efficient algorithm for generating a list of primes in sequence and your estimate of a couple of years is way off (as in "many many lifetimes of the universe way off"). Even testing whether a number is prime is not efficient.
The reason work is concentrated on Mersenne primes is that there there is a particularly fast test for primality for numbers of the form 2^n-1
"The particles are so far apart that if you were to stand in the ring, you wouldn't even know it," said Verbiscer.
Or perhaps you'd be too preoccupied wondering wtf you were standing on to notice whether there was a ring.
You are making this more complicated than it needs to be.
Let's assume a population of 4 thousand if you like. I hope you'll agree there are 4 equally likely possibilities:
1) M - M 1000
2) M - F 1000
3) F - M 1000
4) F - F 1000
Then we apply the random selection and the further knowledge we are given, i.e. at least one of the children is a girl. This discounts M - M and we can deduce the probability of F - F is 1000/3000.
Also from the table above we can work out if we know the eldest is F then the chance of the other being a girl is 1/2 and if we know the youngest is F then the chance of the other being a girl is also 1/2.
And hence we have four options. Either we've got F/[M] or F/[F] if we've learned the first one, or we have [F]/F or [M]/F if we've learned the second one. We don't know which to use, because we don't know which we've learned, but luckily they have the same 50/50 odds.
The mistake here is you've included the F/F set twice because you are treating F/[F] and [F]/F as different sets, which they are not. Consider what you're saying here, that p([F]/F or F/[F]) is twice p(F/M) and twice p(M/F). Or another way of looking at it is the probability of the eldest being F is 75% if you consider F/[M], F/[F], [F]/F and [M]/F to be equally likely (25%), which is incorrect.
It's only when the original choice of the family, in some way, depended on one of the children being female that the probability changes to 1/3. Like if you go around selecting families with one daughter, which means there's a 2/3 chance the other is a son.
For the purpose of this probability calculation, the knowledge we have "at least one daughter" is equivalent to "randomly select from families with at least one girl". In both cases we start off with the same information on which to base the calculation. I'm interested to know why you see there's a difference.
Incidentally, if the question was phrased something like "a family was chosen at random, and I met just one of the children, who was a girl", you will get the 50% probability you mention, but this cannot be deduced from the original question . "First child I met was a girl" implies "at least one daughter" but the reverse is not true.
The GP is correct in this case as they did not specify whether a particular child was a girl. All we know is that at least one is a girl.
You are correct that "telling us the gender of a child tells us nothing about the other one", but we've not been told which of the children is a girl so this this is not relevant here. All we know is that we have 3 equally likely possibilities - M/F, F/M and F/F.
So in this example, these questions mean the same thing:
A family with two children is chosen at random from a large population. If I tell you only that they have at least one daughter, what is the probability that both children are girls?
If we pick out two parents who have at least one girl, what are the odds that their other child is a girl?
What is relevant is how the questioner knows that there is at least one daughter e.g. by asking the parents "Is your eldest a girl?" or "do you have any daughters?" gives probabilities of 0.5 and 1/3 respectively, but the way the question was phrased implies the latter.
In that case the probability will be "close to 50%" assuming Mary is a reasonably rare name amongst girls.
Assume 10% of girls are named Mary, and a sample size of 2000
Oldest child - Youngest
Boy - Boy 500
Boy - Mary 50
Boy - Girl not mary 450
Mary - Boy 50
Mary - Mary 5
Mary - Girl not mary 45
Girl not Mary - Boy 450
Girl not mary - mary 45
Girl not mary - girl not mary 405
Probability of 2 girls assuming at least one is called Mary = (5 + 45 + 45 + 405)/(2000 - 500 - 450) = 500/1050
This is still not 50% but p(2 girls) does approach 50% as p(girls name is Mary) approaches 0
Your second example is only true if you add an additional assumption: that a family never has 2 children with the same name, in which case your question is better expressed as "If I tell you only that they have exactly one child named Mary, what is the probability that both children are girls?". In this case the probability is 50% as you point out.
However, if a family can have 2 children with the same name the probability will depend on the proportion of Marys amongst girls. For example if all girls are called Mary, your second question *is* the same as the first one and the probability is 1/3. If Mary is a rare name (as in the real world), the probability will be slightly less than 50%.
Certain employees produce chunks of data - whether words or software code - that later pop up in other messages. The people copied most often, Cataphora concludes, are thought leaders.
In my experience the code that is discussed in emails is just as likely to be because it is bad as it is because it is good and I'm sure the examples at http://thedailywtf.com/ often "pop up in other messages".
Good managers already know the value of their staff by talking to them, talking to their colleagues and assessing their work. If a manager has to resort to analytics like this at least a corporation knows where their management problems lie.
As other replies have stated it depends on the pressure and at about 0.15 atm or less, it will be a gas at this temperature.
However, the triple-point of methane is at about 0.1 atm which means that methane cannot exist in liquid form anyway given the very low atmospheric pressure on Pluto (1/100,000 atm or less). If you reduce the temperature by just a few degrees the gaseous methane will deposit as a solid, without passing through the liquid phase and in fact, solid methane is found on the surface of pluto.
Clearly these subs were tracking the 2 satellites that collided last week http://science.slashdot.org/article.pl?sid=09/02/11/2318226. The six day delay can be explained by the difference in speed of a nuclear sub compared to a satellite.
_My_ problem however is: why did mutation _B_ happen and get selected by natural selection? And _if_ it causes a harmful trait, why didn't natural selection eliminate it yet?
I think the argument goes something like this:
Mutation B (tail-size preference) occurs randomly. Initially this provides neither a benefit or a hindrance.
A male individual with mutation A (larger tail size) appears. This male will chosen over males without the mutation by females with mutation B, and has an equal chance of being chosen by females without mutation B. So long as the larger tail size is not a hindrance at this stage, there is now a selection pressure for larger tails.
Being in a minority, males with larger tails have less male competition for females with mutation B than for those who don't have a preference, so tend to mate with females who have a preference. This means their offspring have a good chance of having genes for both the long-tail male trait, and the long-tail preference female trait. Mutations A and B now tend to appear together in individuals.
So now we have a situation where long-tailed peacocks are likely to pass on the long-tail preference gene and where they do averagely well with non-choosy females and better than average with choosy females, so the long-tail preference gene increases in the population in general.
Which means peacocks with short tails do poorly, until all members of the population eventually have both the long-tail gene and the long-tail preference gene. And there's still selection pressure for even longer tails, so average tail-length tends to increase until the benefits of having a long tail are outweighed by the disadvantages in terms of defense etc.
Bingo. That's the whole point: if it was a handicap for the species, it should have happened. That's the basic prediction of natural selection.
I think this is the basis for what I see as your mis-understandings regarding evolution. Evolution does not produce species which are optimally adapted to the environment in which they find themselves - natural selection can only work on the genes that already exist, and we need to remember that new genes are created in a random process. Over time you might expect deleterious traits to disappear but this can't happen unless there's a mutation (or a new/amended gene introduced through breeding).
You've also managed to underestimate the importance of sexual selection in evolution. Natural selection concerns the ability of genes to be passed on to following generations. Genes will only be passed on if the organism both survives to sexual maturity (i.e. is sufficiently adapted to the environment) and manages to mate successfully. The latter provides a _very_ strong selection pressure regarding genes affecting sexual attractiveness and behaviour.
You may be right that the peacock's tail provides other advantages other than sexual attractiveness, but even if it doesn't and it in fact makes the peacock less adapted to it's environment, its advantages in helping it reproduce can be enough to ensure it's genes are passed on rather than those of peacocks with smaller tails.
To explain why the gene doesn't disappear from the population you need to consider the long-term mating success of the lineage without the genes. And you need to take into account there are 2 traits here - there are genes that cause males to have large tails, and others that cause females to prefer males with large tails. The argument is too complex for me to remember accurately, but it's in one of Richard Dawkins books I think.
If a smaller tail were an advantage, then their kids live longer and get more chances to reproduce. With each other if nobody else wants them. Repeat a few generations, and that trait will be on its way to extinction.
They may have more chances to reproduce but you need to consider they're in a population of females that predominantly prefer large tails. And they themselves still carry the large tail preference gene.
Nobody has ever used the (non)existence of dinosaurs to push public policy that handicaps our society's productiveness while giving less scrupulous countries the ability to gain yet another competitive edge on us.
My response was not anything to do with the direction public policy should take, but with the science behind the predictions of climate change - I was merely highlighting that science often uses indirect evidence to formulate theories and this in no way means the science is not valid. IMO it's important the scientific research should be independent of the possible implications of any conclusion, one way or another.
The post to which I responded used emotive and unhelpful language to criticize a lot of good science - the debate would benefit from people concentrating more on the science sometimes, rather than the politics surrounding it.
Fantastic demands require fantastic proof.
So let's help the scientists do some "fantastic science" so we know more about the situation we're in, before knocking them. Unfortunately, we will never have access to direct measurements of historical climate so the more we refine these indirect measurement techniques the better. However, it's unlikely that there will ever be "proof" for those people who think indirect climate measurements should be ignored by climate scientists.
I wouldn't have thought climate scientists would have much of a problem with climate proxy indicators being referred to as indirect evidence so there's no need for your use of the pejorative term "euphemism" there.
And if you think "circumstantial evidence" includes race, sex, and religion in a court of law, you clearly don't have an understanding of this term either.
Read up a bit on the science involved and you might be surprised to find some of these proxy indicators are little different than using the existence of fossils to infer the presence of dinosaurs in prehistory.
Or perhaps you don't believe in dinosaurs?
This project appears to be good science, whatever your views on climate change - it's recognizing there is a limit to the accuracy of what we currently use as proxy indicators, but by comparing proxy indicator predictions against actual measurements, it hopes to refine our use of these indirect measurements so we can use them to get a clearer idea of the causes of current climate trends.
To people who don't know about UK politics this post might imply that Scotland is not governed by the British (Westminster) government. Scotland still is, though many powers have been devolved to the Scottish parliament.
If the Conservatives form the next British government, Scotland will still be affected.
http://www.parliament.uk/about/how/role/devolved.cfm
Exceptions include information other that that covered by the Official Secrets Act.
There are also a whole lot of exemptions, such as data that is commercially sensitive, related to criminal investigations or where disclosure would contravene the Data Protection Act etc. When a request is refused the reason for the exemption must be given to the requester.
In practise the Act has meant a lot of information is now public where it wouldn't have been before.
The problem is that evolution is a very slow process. This has not been a problem in the past because environments tend to change slowly too, allowing species to adapt rather than become extinct. Many species don't adapt and become extinct, but in prehistoric times the rate that new species were created was faster than the rate at which they went extinct.
Man has the unique ability to change the environment to suit ourselves, it's what we are really good at, and this is one of the reasons why we are seeing so many extinctions at present, particularly in the last few hundred years or so.
It's not arrogance to realize our major role in the high current rate of extinction - other "natural" causes pale into significance compared to the effect man has. The only sign of hope (assuming bio-diversity is seen as a good thing) is that we're also intelligent enough to realize the effect we're having. I'm not so hopeful whether we'll be able to control our natural instincts and preserve environments rather than exploit them and move on. We might be able to do this for the next hundred years or so, but what about the next thousand or ten thousand years?
Of course you're quite wrong here.
Mathematics provides a lot of the tools that show that evolution is not surprising, can explain "holes" in the fossil record etc. For example probability theory shows it would be unlikely for there to be no holes in the fossil record give the low probability that any individual organism is fossilised, let alone the low probability that we find it.
Mathematics can also help us understand why it is possible for single-celled organisms to eventually evolve into the complex life we see today - how many ancestors do you think a human has since multi-celled organisms appeared? It's a lot!! Each generation provides opportunities for random mutation and natural selection - add them all up and most mathematicians should see why evolution creates the diversity of life we have today.
We'll probably never have direct evidence of how DNA appeared but you might like to think about the following question: given a planet with the same general environment as the earth, a source of heat, and the same elemental composition, use your knowlededge of math and chemistry (particularly carbon-chemistry) to predict the nature of the most complex molecules that exist after 2 billion years or so. Can you really be sure that with such a large experiment and such long timescales, you wouldn't end up with a molecule that can self-replicate?
And once you have a molecule that can do that, there's no stopping it - it can continue to evolve so that it can begin to affect it's local environment to make it easier to survive and replicate etc etc. Eventually you have DNA.
If a mathematician has a problem grasping the theory of evolution it's due to their lack of knowledge about chemistry, not because the math doesn't add up.
> So the "Proof" of global warming is basically that we have no better theory?
I'm not sure what you mean by Proof of global warming. Global warming is a fact - there are measurements that show this clearly.
> We are being told that Global temperatures have gone up by fractions of a degree.
About 0.5 Celsius increase in 40 years I think. It doesn't sound like much but to climate scientists it's a big deal. It's a lot of extra heat in the atmosphere.
> I would be amazed if they could actually get all that data together without the margin of error being at least fractions of a degree.
Accurate readings of temperature have been possible for over a hundred years now and the margin of error estimating temperatures 1000 years ago using indirect means is only +/- 0.5 degrees. Statistical analysis of actual measurements means we can be effectively certain that global warming is real.
> I can have 3 different digital thermometers in different places in my yard and they will all read different.
Try an experiment then - take readings from each thermometer over a period of time and plot a graph of temperature against time for each of them. See how they track each other? Now consider doing this for 100 years in thousands of places around the world, analyse the results statistically and you'll see a similar pattern. They won't track each other as well as the thermometers in your back yard due to weather being different in different places but you will see a clear trend.
> Going back 100 years they didn't have digital thermometers.
They had mercury thermometers - a technology still used around the world today to decide whether to rush children to A&E. Sometimes it's surprising how good older measurements were (e.g. measurements taken in the same locality but by different people agree very well).
> Temperatures in Cities are warmer than outside cities.
This is true and you will find temperatures in urban areas that were once rural have increased significantly. Of course scientists are aware of this effect, and take this into account e.g. by discarding measurements from existing urban areas.
> Global warming appears to me to be science with an agenda behind it. With something as big and as complex as this, I think you could try to have the numbers say just about whatever you want them to say.
I think there are people on both sides who have an agenda and this doesn't help things. However, when you look at the data from a scientific viewpoint it clearly shows that global warming is real. There's really little doubt about this and even groups opposed to the scientific consensus of man-made warming now concede this fact.
The debate has moved on now - it's not whether global warming is happening, but whether its causes are man-made. And the majority of scientists feel this also is pretty much confirmed now and the debate should be about what we can do about it.
> The problem is the AGW guys shouting that the argument is over and that there's a consensus and everybody should just shut it and get in line. To hell with that. That's not science, but rather a nasty form of political orthodoxy.
The GP post concerned statistical fluctuations in mean temperatures - to me this is science.
You raise possible economic and human consequences of taking steps to deal with a perceived problem - to me this is political.
I think your post demonstrates how easy it is for the discussions on climate science to turn into political discussions. Somehow we have to keep these separate, as political considerations should never be a factor in determining scientific truth.
There is a discussion to be had regarding whether we should be making wide-ranging economic changes based on theories that are x% likely to be correct, but the consequence of these changes (or the impact of not taking action) should not have an impact on the science, other than to act as a guide to decision-makers where best to allocate research funds.