Hardly. Given that there are only two countries, other than the US, on the planet not using metric I'd have actually thought it would be an amazing coincident to meet an alien who did NOT use metric. Since I used to have a green card I even used to be one of them.;-)
Volume and mass are defined based on a cube (length^3) of water and its specific gravity. Doesn't sound too specific to our planet.
Well I don't know which planet you are referring to as "our" but here on planet Earth the SI units of volume are defined using the length unit (metre) alone. Mass is based on a lump of platinum-iridium alloy kept in Paris. However there is an attempt to replace this with a more fundamental measurement based on a perfect sphere of pure silicon.
Wrong. Photons have energy because they have momentum, they have zero mass...and since mass is a Lorentz invariant that is always true in all inertial frames. Einstein's proper energy-momentum relationship is:
E^2 = p^2 c^2 + m^2 c^4
So next time you see someone with an "E=mc^2" T-shirt on when they are moving you can point out that their T-shirt is wrong!
The more you read the works of the ancient physicists, you will discover that they certainly were not people "without any clue", but often trying to wrap their minds around some serious observations.
If you use hindsight to hand pick the wild speculations which happened to hit near the mark and ignore the rest then of course it seems like they had some amazing insights. For example, Newton was an amazing physicist and mathematician, he even speculated that light was made of particles. He was also an alchemist and believed that he could transmute lead into gold.
The more you read ALL the works the ancient physicists, and not the works which have been selected with modern hindsight, the more you will realize that, while they were brilliant people, when they were making wild speculation they really were doing just that - making wild speculations.
Firstly you are wrong in saying that a photon has no mass. It has no rest mass, but it certainly has energy, and even momentum (hv/c).
Wrong. I am completely and absolutely correct to say that the photon has no mass. Mass is something called a Lorentz invariant and does not change - it is a common mistake which people often make. The gamma in p=gamma*m*v comes from the velocity (look up 4-velocity) and not the mass. Hence a photon has zero mass in all inertial reference frames regardless of its energy. Even Einstein warned that it was wrong to think of the mass as changing.
Force is not just m*a, but even more correctly described as the change of momentum dp/dt.
Under Newtonian mechanics, which is what we are talking about here, the two are identically equivalent for particles of constant mass. Since, even under relativity, photons have a constant mass this certainly applies. Since Newtonian gravity uses mass as the charge of the gravitational force any particle with no mass feels no force.
There are many papers that speculate that is light is a particular, what must be the effect of gravity upon it, dating from several years before Cavendish even.
True, in fact Newton was probably the first, but the key word here is speculate. They had absolutely no idea of the properties of the particle nor any evidence for it. Also none of these, to my knowledge, considered the effect on light if the light "corpuscles" (as Newton called them) had zero mass.
Perhaps a kernel upgrade would be a better analogy for slashdot? The core of the system has had a major improvement but the desktop GUI is not really affected. So, unless you are a kernel hacker/gravitational physicist there are not many noticeable changes!
But everyone that thinks otherwise is welcome to calculate sqrt(1 - v^2/c^2) for their experiment's velocity and see if the values vary significantly
I'm not sure that works too well - my experiment is large and very stationary but the particles we collide in the middle have a gamma [which is 1/sqrt(1 - v^2/c^2)] of well over 3,500.
Two things: First the question is what deflection does Newton's law of gravity predict for the deflection of light, not did Newton know that light was massless.
Two: Newton and Cavendish did not know that light was massless but we do and so Newton's law predicts no deflection i.e. Cavendish got it wrong but so would anyone else predicting the behaviour of a particle which was discovered about 100 years after he wrote his paper!
You don't need to know what the mass of light is...
Actually you do because if the mass is zero there is no force according to Newton's law of gravity and hence no deflection. Cavendish did not know this in 1804.
Actually it does, but by half the amount predicted by general relativity.
Actually it does NOT. Cavendish made suppositions without any clue to what light was - the date on Cavendish's paper was 1804, well before even Maxwell's equations let alone photons were known. Having no clue about light they supposed that it would follow a trajectory as any massive body does - quite reasonable not given any evidence to the contrary - but now we know better!
Newton's statement of his law explicitly states that the attraction is proportional to the masses of the bodies and, since a photon has no mass, there is no attractive force. So the prediction for light, composed of massless photons, is no deflection. Relying on Wikipedia articles quoting 19th century physics papers attempting to describing the behaviour of particles we discovered in the early 20th century is unlikely to be reliable!
a British MP will probably be more knowledgeable about government policies...
Not so much the average MPs, at least the ones not on the front benches - given recent evidence they seem to spend most of their time trying to figure out how to fiddle their expenses and even then most seem rather incompetent at it.
Britain is much, much smaller than the U.S. and so the domestic and foreign affairs issues are smaller in scope
It's true the UK is smaller, but is still 20% the size (in population terms) of the US. However it has a very centralized form of government so Westminster deals with all education, health, transport issues directly etc. unlike the US where these are partly or entirely devolved to states. As for foreign affairs I'm not convinced that country size makes much of a difference there especially given the UK's history of international involvement. The number of resources might be less but the main decision that politicians have to make is whether, and how, to get involved.
In political debates or being invited to the WhiteHouse you will need to have your questions screened before hand. Even the President does it.
Which is a very good argument to have a prime minister and not a president. As a PM you have to know what is going on and be able to answer questions on your feet - and not just from the media but from MPs in parliament as well. One of the things that really surprised me when I lived in the US was that interviewers never seemed to ask hard questions - or at least push them home if they did ask them. The US may have a free press, but it is a strongly coerced free press.
It's your right to walk away from an interview at any time.
True. However if you are the CEO of a major international corporation and you cannot handle a reasonable, politely asked question from a major international media organization you are in the wrong job.
Unfortunately, physics is implacable, its laws are not subject to negotiation. Until we find ways to (1) move faster than sound without creating a sonic boom and (2) move faster than sound without spending much more fuel
We already know ways to do both of those things: run a maglev train in a vacuum. The problem is an engineering and economic one: how to build a very long, safe vacuum tube. So go and blame it on the engineers and leave us physicists alone!
Ever noticed that we seem to be getting more and more lawyers and fewer and fewer physicists? This is a very cunning plan by the Chinese to fix this. You pass the laws of physics as actual legislative laws and, by the time all those lawyers graduate law school they are actually trained as physicists. By this time next week 3x10^8 m/s won't be just a good idea it really will be the law!
First we would have to agree on what an Angel was, and how one would confirm the observation of an angel, so no, that's not a testable hypothesis
No, that is not how science works. What happens is you go and make your observations and then publish your data and their interpretation. These are then discussed by the community, in conferences and papers, until a consensus is reached - this may take a long time, require additional test, evidence etc.
Ironically your suggestion that there is some central authority which decides what everything is and how to observe or test them is very much the picture of science painted at school. If you actually do science at the university level or, better still, research degree you'd know better.
"Is your hypothesis testable?" If the answer is "yes", it's science, if the answer is "no", it's religion.
Sighting an angel is a testable hypothesis - you go and look for one. You might not find one on Earth today but the Universe is a BIG place. However I would not regard such a hypthesis as science. In the same vein string theory has hypotheses which are similarly incredibly hard to test given current technology but I would hardly regard that as religion (unless I was wanting to wind-up a string theorist;-).
The big difference between science and religion is that science answers the question "how" and religion worries about "why". Religion gets into a huge amount of trouble when it tries to answer "how" and scientists get into just as much trouble when we try to answer "why".
Now, I'm going to flip this on you a bit: You've been hurting from the gasoline prices lately, yes? Pretty much everybody is.
Sorry to burst your bubble but, according to wikipedia the battery pack for the Tesla model in question costs $36k and has a lifetime of 100k miles which is 36 cents/mile travelled to which you can add about 3 cents/mile in electricity costs (86kWh per full charge at 200 miles/charge and assume 7 cents/kWh). Current US petrol prices seem to be about $3.55 per US gallon so for a petrol car to have the same fuel costs as the Tesla it would need to have a fuel consumption worse than 9.1 miles per gallon...which is about comparable to a hummer.
So, unless the cost of petrol gets very significantly higher (by x3-4) or the cost of batteries drops considerably the fuel cost of an electric vehicle is significantly higher than a petrol driven one. I wish that were not the case but sadly, for now, it is.
Top Gear's tests cover the real-world driving conditions of very few people. Sure, there are people who flog exotic and sportscars on the street...
Hang on, isn't the Tesla model they tested supposed to be an exotic sports car? I agree that this is not how most people would drive a car but most people don't own a seriously expensive sports car, let alone a car capable of being on the fun side of 185 mph (they might get it there but I doubt it wil be much fun!). It does not seem unreasonable to presume that someone who spends a serious amount of money on a car like this might want to take it to a track and put it through its paces. This is not a normal car so why assume normal driving conditions?
...with respect to aeroplanes the degree of automation these days compared to 20, 30 years ago is astounding, for precisely the same reason: it's been shown to save lives a few orders of magnitude more times than the ones they take.
This is, I think, the root of the problem. Using statistics works fine for aeroplanes because, every time you fly, you are essentially getting onto a random plane with a random pilot and so you want them to be very safe on average. However when you drive it is always you driving so, while you might on average improve the quality of driving with computers that is not what is important to each individual anymore. The question which needs to be answered is "is it better at driving than me?" and since it has been shown that we generally tend to think of ourselves as better drivers than we actually are convincing people will not be easy!
For example, supposing there is an idiot driving and they do something stupid will the computer be able to handle some crazy situation it might not have seen before? Will it speed if it needs to to avoid an accident: very unusual but I know one person who was about to overtake a lorry on a motorway and saw the load start to slip so they floored it to avoid being in the accident...would a computer be able to handle that especially since it will have speed limits pre-programmed? Statistically these are rare situations but convincing early adopters will be hard because you won't have enough statistics to know how often an unusual situation which the system cannot correctly handle will occur.
People aren't suggesting computer controlled passenger jets at this point, because they're already in the air. You don't really think the pilot is really touching the controls for the entire flight, do you?
By that definition we already have computer controlled cars thanks to cruise control. With planes the pilot is in the cockpit continuously monitoring the situation and ready to take over when needed. This will not be the case in a computer controlled car...because if it were why would anyone want to buy it? If they have to be looking at the traffic and monitoring it all the time they might as well just drive themselves.
The designs are ready for the next generation of aircraft controls, where the pilot will be a babysitter for the computer. Why should cars be different?
As I said above: if I have to babysit the car why not just drive myself anyway? Cars are also in an environment where things happen very, very rapidly. In a plane there is usually far more time for a pilot to realize there is a problem and take over - the exceptions being take off and landing when the pilot is flying. In a car if the computer mistakes a shadow for a pedestrian and swerves into oncoming traffic to avoid it there will probably not be time to react.
Slashdot Mirror
Well that would be an amazing coincidence.
Hardly. Given that there are only two countries, other than the US, on the planet not using metric I'd have actually thought it would be an amazing coincident to meet an alien who did NOT use metric. Since I used to have a green card I even used to be one of them. ;-)
Volume and mass are defined based on a cube (length^3) of water and its specific gravity. Doesn't sound too specific to our planet.
Well I don't know which planet you are referring to as "our" but here on planet Earth the SI units of volume are defined using the length unit (metre) alone. Mass is based on a lump of platinum-iridium alloy kept in Paris. However there is an attempt to replace this with a more fundamental measurement based on a perfect sphere of pure silicon.
Weight is measured in kg, force in Newton. There is a difference between the two, you know.
Weight is a force and is measured in newtons. Mass is measured in kilograms. There is a difference between the two but clearly you did not know!
it's reasonable to assume that light particles did have a mass
It was reasonable for primitive cultures to assume that the world was flat based on their available evidence. However that did not make them right!
Photons have mass, because they have energy.
Wrong. Photons have energy because they have momentum, they have zero mass...and since mass is a Lorentz invariant that is always true in all inertial frames. Einstein's proper energy-momentum relationship is:
E^2 = p^2 c^2 + m^2 c^4
So next time you see someone with an "E=mc^2" T-shirt on when they are moving you can point out that their T-shirt is wrong!
The more you read the works of the ancient physicists, you will discover that they certainly were not people "without any clue", but often trying to wrap their minds around some serious observations.
If you use hindsight to hand pick the wild speculations which happened to hit near the mark and ignore the rest then of course it seems like they had some amazing insights. For example, Newton was an amazing physicist and mathematician, he even speculated that light was made of particles. He was also an alchemist and believed that he could transmute lead into gold.
The more you read ALL the works the ancient physicists, and not the works which have been selected with modern hindsight, the more you will realize that, while they were brilliant people, when they were making wild speculation they really were doing just that - making wild speculations.
Firstly you are wrong in saying that a photon has no mass. It has no rest mass, but it certainly has energy, and even momentum (hv/c).
Wrong. I am completely and absolutely correct to say that the photon has no mass. Mass is something called a Lorentz invariant and does not change - it is a common mistake which people often make. The gamma in p=gamma*m*v comes from the velocity (look up 4-velocity) and not the mass. Hence a photon has zero mass in all inertial reference frames regardless of its energy. Even Einstein warned that it was wrong to think of the mass as changing.
Force is not just m*a, but even more correctly described as the change of momentum dp/dt.
Under Newtonian mechanics, which is what we are talking about here, the two are identically equivalent for particles of constant mass. Since, even under relativity, photons have a constant mass this certainly applies. Since Newtonian gravity uses mass as the charge of the gravitational force any particle with no mass feels no force.
There are many papers that speculate that is light is a particular, what must be the effect of gravity upon it, dating from several years before Cavendish even.
True, in fact Newton was probably the first, but the key word here is speculate. They had absolutely no idea of the properties of the particle nor any evidence for it. Also none of these, to my knowledge, considered the effect on light if the light "corpuscles" (as Newton called them) had zero mass.
That's nothing compared the the velocity of the large mass of hydrogen itself orbiting the centre of its galaxy.
Perhaps a kernel upgrade would be a better analogy for slashdot? The core of the system has had a major improvement but the desktop GUI is not really affected. So, unless you are a kernel hacker/gravitational physicist there are not many noticeable changes!
But everyone that thinks otherwise is welcome to calculate sqrt(1 - v^2/c^2) for their experiment's velocity and see if the values vary significantly
I'm not sure that works too well - my experiment is large and very stationary but the particles we collide in the middle have a gamma [which is 1/sqrt(1 - v^2/c^2)] of well over 3,500.
Two things: First the question is what deflection does Newton's law of gravity predict for the deflection of light, not did Newton know that light was massless.
Two: Newton and Cavendish did not know that light was massless but we do and so Newton's law predicts no deflection i.e. Cavendish got it wrong but so would anyone else predicting the behaviour of a particle which was discovered about 100 years after he wrote his paper!
You don't need to know what the mass of light is...
Actually you do because if the mass is zero there is no force according to Newton's law of gravity and hence no deflection. Cavendish did not know this in 1804.
Actually it does, but by half the amount predicted by general relativity.
Actually it does NOT. Cavendish made suppositions without any clue to what light was - the date on Cavendish's paper was 1804, well before even Maxwell's equations let alone photons were known. Having no clue about light they supposed that it would follow a trajectory as any massive body does - quite reasonable not given any evidence to the contrary - but now we know better!
Newton's statement of his law explicitly states that the attraction is proportional to the masses of the bodies and, since a photon has no mass, there is no attractive force. So the prediction for light, composed of massless photons, is no deflection. Relying on Wikipedia articles quoting 19th century physics papers attempting to describing the behaviour of particles we discovered in the early 20th century is unlikely to be reliable!
a British MP will probably be more knowledgeable about government policies...
Not so much the average MPs, at least the ones not on the front benches - given recent evidence they seem to spend most of their time trying to figure out how to fiddle their expenses and even then most seem rather incompetent at it.
Britain is much, much smaller than the U.S. and so the domestic and foreign affairs issues are smaller in scope
It's true the UK is smaller, but is still 20% the size (in population terms) of the US. However it has a very centralized form of government so Westminster deals with all education, health, transport issues directly etc. unlike the US where these are partly or entirely devolved to states. As for foreign affairs I'm not convinced that country size makes much of a difference there especially given the UK's history of international involvement. The number of resources might be less but the main decision that politicians have to make is whether, and how, to get involved.
In political debates or being invited to the WhiteHouse you will need to have your questions screened before hand. Even the President does it.
Which is a very good argument to have a prime minister and not a president. As a PM you have to know what is going on and be able to answer questions on your feet - and not just from the media but from MPs in parliament as well. One of the things that really surprised me when I lived in the US was that interviewers never seemed to ask hard questions - or at least push them home if they did ask them. The US may have a free press, but it is a strongly coerced free press.
It's your right to walk away from an interview at any time.
True. However if you are the CEO of a major international corporation and you cannot handle a reasonable, politely asked question from a major international media organization you are in the wrong job.
Unfortunately, physics is implacable, its laws are not subject to negotiation. Until we find ways to (1) move faster than sound without creating a sonic boom and (2) move faster than sound without spending much more fuel
We already know ways to do both of those things: run a maglev train in a vacuum. The problem is an engineering and economic one: how to build a very long, safe vacuum tube. So go and blame it on the engineers and leave us physicists alone!
Bats have it worse than birds, for some reason that's still not understood.
Perhaps for wind power but, given that they are generally nocturnal, I doubt a solar plant will be much of a worry to them.
The plot thickens...
Ever noticed that we seem to be getting more and more lawyers and fewer and fewer physicists? This is a very cunning plan by the Chinese to fix this. You pass the laws of physics as actual legislative laws and, by the time all those lawyers graduate law school they are actually trained as physicists. By this time next week 3x10^8 m/s won't be just a good idea it really will be the law!
First we would have to agree on what an Angel was, and how one would confirm the observation of an angel, so no, that's not a testable hypothesis
No, that is not how science works. What happens is you go and make your observations and then publish your data and their interpretation. These are then discussed by the community, in conferences and papers, until a consensus is reached - this may take a long time, require additional test, evidence etc.
Ironically your suggestion that there is some central authority which decides what everything is and how to observe or test them is very much the picture of science painted at school. If you actually do science at the university level or, better still, research degree you'd know better.
"Is your hypothesis testable?" If the answer is "yes", it's science, if the answer is "no", it's religion.
Sighting an angel is a testable hypothesis - you go and look for one. You might not find one on Earth today but the Universe is a BIG place. However I would not regard such a hypthesis as science. In the same vein string theory has hypotheses which are similarly incredibly hard to test given current technology but I would hardly regard that as religion (unless I was wanting to wind-up a string theorist ;-).
The big difference between science and religion is that science answers the question "how" and religion worries about "why". Religion gets into a huge amount of trouble when it tries to answer "how" and scientists get into just as much trouble when we try to answer "why".
Now, I'm going to flip this on you a bit: You've been hurting from the gasoline prices lately, yes? Pretty much everybody is.
Sorry to burst your bubble but, according to wikipedia the battery pack for the Tesla model in question costs $36k and has a lifetime of 100k miles which is 36 cents/mile travelled to which you can add about 3 cents/mile in electricity costs (86kWh per full charge at 200 miles/charge and assume 7 cents/kWh). Current US petrol prices seem to be about $3.55 per US gallon so for a petrol car to have the same fuel costs as the Tesla it would need to have a fuel consumption worse than 9.1 miles per gallon...which is about comparable to a hummer.
So, unless the cost of petrol gets very significantly higher (by x3-4) or the cost of batteries drops considerably the fuel cost of an electric vehicle is significantly higher than a petrol driven one. I wish that were not the case but sadly, for now, it is.
Top Gear's tests cover the real-world driving conditions of very few people. Sure, there are people who flog exotic and sportscars on the street...
Hang on, isn't the Tesla model they tested supposed to be an exotic sports car? I agree that this is not how most people would drive a car but most people don't own a seriously expensive sports car, let alone a car capable of being on the fun side of 185 mph (they might get it there but I doubt it wil be much fun!). It does not seem unreasonable to presume that someone who spends a serious amount of money on a car like this might want to take it to a track and put it through its paces. This is not a normal car so why assume normal driving conditions?
...with respect to aeroplanes the degree of automation these days compared to 20, 30 years ago is astounding, for precisely the same reason: it's been shown to save lives a few orders of magnitude more times than the ones they take.
This is, I think, the root of the problem. Using statistics works fine for aeroplanes because, every time you fly, you are essentially getting onto a random plane with a random pilot and so you want them to be very safe on average. However when you drive it is always you driving so, while you might on average improve the quality of driving with computers that is not what is important to each individual anymore. The question which needs to be answered is "is it better at driving than me?" and since it has been shown that we generally tend to think of ourselves as better drivers than we actually are convincing people will not be easy!
For example, supposing there is an idiot driving and they do something stupid will the computer be able to handle some crazy situation it might not have seen before? Will it speed if it needs to to avoid an accident: very unusual but I know one person who was about to overtake a lorry on a motorway and saw the load start to slip so they floored it to avoid being in the accident...would a computer be able to handle that especially since it will have speed limits pre-programmed? Statistically these are rare situations but convincing early adopters will be hard because you won't have enough statistics to know how often an unusual situation which the system cannot correctly handle will occur.
People aren't suggesting computer controlled passenger jets at this point, because they're already in the air. You don't really think the pilot is really touching the controls for the entire flight, do you?
By that definition we already have computer controlled cars thanks to cruise control. With planes the pilot is in the cockpit continuously monitoring the situation and ready to take over when needed. This will not be the case in a computer controlled car...because if it were why would anyone want to buy it? If they have to be looking at the traffic and monitoring it all the time they might as well just drive themselves.
The designs are ready for the next generation of aircraft controls, where the pilot will be a babysitter for the computer. Why should cars be different?
As I said above: if I have to babysit the car why not just drive myself anyway? Cars are also in an environment where things happen very, very rapidly. In a plane there is usually far more time for a pilot to realize there is a problem and take over - the exceptions being take off and landing when the pilot is flying. In a car if the computer mistakes a shadow for a pedestrian and swerves into oncoming traffic to avoid it there will probably not be time to react.