You're confused as to the definition of shallow and deep water. The water is "shallow" for the purposes of wavespeed calculation when it's less than 1/20 of the wavelength. In a tsunami the wavelength can be around 200km, therefore the water is considered shallow even in open ocean.
To quote this page: A tsunami can have a wavelength in excess of 100 km and period on the order of one hour. Because it has such a long wavelength, a tsunami is a shallow-water wave. Shallow-water waves move with a speed equal to the square root of the product of the acceleration of gravity and the water depth.
In any case, discussing tsunamis isn't really relevant to the idea of surfing on a rogue wave. You haven't commented on my figures- 50m high wave, 100m wavelength, 45kph speed- what kind of wave can you ride at this speed? Note that if the slope was 45 degrees, you would actually have to travel down the face at 45*sqrt(2) = 65kph in order to move forwards at 45kph. The steeper the wave the faster this would need be.
Tsunamis can move faster than 200 metres per second because they have extremely long wavelengths (hundreds of km). In this case the speed is not related to the wave height at all, only water depth. But say the height was 50m and the wavelenth was 100m, then the speed would be 45kph or about 30mph in deep water. I'm betting that would be too fast to ride a wave of that steepness because the force of gravity down the slope must overcome the air+water resistance. There's a reason large waves in Hawaii can only be ridden as they begin to crest, as on an offshore ridge at Jaws.
Cool idea but I doubt any of these waves would be ridable. A wave's speed in deep water is proportional to the square-root of it's wavelength, so these big waves are moving pretty fast and they just wouldn't be steep enough to carry you along with them. Also there's good reason to believe they're very short lived.
Consider the alternative phrasing: "relative speed". This is inferior to the given wording because it suggests that the speed of one was subtracted from the speed of the other, which is not the case for precisely the reasons you point out.
Furthermore, using simply "speed" is insufficient because it ignores the fact that both objects are moving.
Finally using "velocity" by itself suffers from the same problem as well as being non-specific with respect to direction.
In practice there is scientifically nothing wrong with giving the magnitude of velocity in this way. This is natural language after all, not an equation. If the reader doesn't understand the meaning, they've got bigger problems understanding the rest of it!
I think the size of the prototype is just right. The real breakthrough application area right now is camera phones. I have a camera on the back of my Sony Ericsson T610 that I've never used. Mobile phone cameras are held back by one massive obstacle: They're currently fixed zoom and fixed focus. Solve that cheaply and a truly massive market is ready made to adopt your solution.
Another fascinating application mentioned in NewScientist's coverage of this stuff is variable zoom security cameras. A security camera could zoom and focus selected portions of the field of view without needing to tilt or swivel the housing. Imagine a kind of moving fisheye effect within the rectangular frame of view. You bolt one of these very cheap cameras to the wall with a very wide field of view and then your operator/software invisibly controls the lens to follow objects closely. Awesome.
Well I don't agree that stupid people should suffer, I do think this Sessions guy is culpable. His $330,000 not only ruined himself and his wife, it has kept the scammers going for years and years. How many more people will they scam on the back of that money?
I think anyone who responds to spam email (scams or otherwise) deserves to be strung up because it creates an atmosphere where that sort of thing is profitable.
Now this may be somewhat off-topic but I'm tired of people trying to use the front page of Slashdot to try to launch their favourite pet jargon. There is no such FLA as FAAQ. Why can't a single A service both "Asked" and "Anticipated"? I mean 4 FAAQ's sake!!
If you can't find a covering set, and for the remaining 11 numbers that looks most likely, then you're right, you can't know for sure that there is no prime.
There may be errors in the below too! You're assuming that there is no proof strategy alternative to covering sets. Maybe no one has thought of an alternative because covering sets have thus far shown the most promise?
Did anyone else notice the date in the corner of the image? It's Febuary 2002. I guess it takes a long time for this kind of reasearch to go from the lab to the media.
The other way of doing it is basically the cold fusion method (call a press conference immediately). Pros and cons.:)
It gets better! 20996011 is necessarily prime as well. So, it's probably something like the 6 millionth prime, so you could store that using only 22 bits! For further compression we'd probably have to prove the Riemann hypothesis.:)
You don't get 100 million euro devices built for the sake of some nice images. They're selling it on the idea of answering some of the fundamental questions about the universe. Like where do the high-energy cosmic rays come from? These are single protons with the energy of a driven golf ball and cannot be explained by current cosmology.
Also interesting to note is that they are planning to use the massive data network required to monitor other things like weather and seismic waves.
One thing that wasn't obvious from the article is that the antennae are not dishes. There are no moving parts. Dishes exist only in the central processor and are effectively CPU resources that can be assigned to multiple research groups simultaneously. If you double the capacity of the CPU, you double the number of virtual dishes available. Mind boggling.
Rotational force? Do you mean torque? Of course and equal and opposite torque is applied between the gyro and the bike, so what? I was talking about conservation of angular momentum.
Why don't you go outside, run and then lean over backwards. I don't know what that might prove but at least you'd probably hurt yourself.
One thing you are right about. If running at full throttle it will be dificult to break suddenly without using a flywheel. Air resistance would prove useful however in helping to tilt the bike backwards. Again this is exactly the same as a runner. It becomes more and more difficult to stop quickly from a sprint, not just because you're moving fast but because you can't get your feet in front of you. Wind drag at that speed allows 100m runners to begin braking.
Finally, humans do have a built in flywheel which is sometimes useful. When jumping through the air or balancing, people often rotate their arms opposite to the direction they are tipping.
A gyro can't just magically tilt the bike any which way. You have to have conservation of momentum. When the acceleration of the bike + the accel due to gravity does not line up with the line joining the ground contact with the centre of gravity, then the system is tipping and rotational inertia is being exchanged with the Earth. You can store some of this RI in a flywheel and then bleed it off later by tipping in the opposite direction. None of this is necessary to explain the braking mechanism though.
You are also dead wrong about the runner. A runner simply cannot lean over backwards quickly without the benefit of a flywheel (or a clothesline around the neck!). You need to get your feet out in front of you, which is achieved by moving them forward faster than your centre of gravity. This is basic classical mechanics, conservation of momentum, etc. I am actually a physicist.
It couldn't throw you backwards, the wheel speeds up until it's in front of you and then begins pushing you back to a stop. This is exactly what happens when you stop running, you have to first accelerate your feet until they're in front of you.
Funny you should say that. I don't think nicotine is necessary to create addictive fast food. There is a growing body of evidence (har har) to support the position that fast food is already highly addictive because of the unnaturally sharp rush of sugar to the brain.
I was planning on buying the QuietComforts when I read this article. It convinced me of the merits of the Etymotic EP-4s especially as I wanted a highly portable solution. Most comparisons I've read say that the Etymotics win hands down as long as you don't mind sticking things into your ears. It's taken me a bit of getting used to but I love them.
Slashdot Mirror
You're confused as to the definition of shallow and deep water. The water is "shallow" for the purposes of wavespeed calculation when it's less than 1/20 of the wavelength. In a tsunami the wavelength can be around 200km, therefore the water is considered shallow even in open ocean.
To quote this page:
A tsunami can have a wavelength in excess of 100 km and period on the order of one hour. Because it has such a long wavelength, a tsunami is a shallow-water wave. Shallow-water waves move with a speed equal to the square root of the product of the acceleration of gravity and the water depth.
In any case, discussing tsunamis isn't really relevant to the idea of surfing on a rogue wave. You haven't commented on my figures- 50m high wave, 100m wavelength, 45kph speed- what kind of wave can you ride at this speed? Note that if the slope was 45 degrees, you would actually have to travel down the face at 45*sqrt(2) = 65kph in order to move forwards at 45kph. The steeper the wave the faster this would need be.
Can't be done.
Cheers.
Tsunamis can move faster than 200 metres per second because they have extremely long wavelengths (hundreds of km). In this case the speed is not related to the wave height at all, only water depth. But say the height was 50m and the wavelenth was 100m, then the speed would be 45kph or about 30mph in deep water. I'm betting that would be too fast to ride a wave of that steepness because the force of gravity down the slope must overcome the air+water resistance. There's a reason large waves in Hawaii can only be ridden as they begin to crest, as on an offshore ridge at Jaws.
Cool idea but I doubt any of these waves would be ridable. A wave's speed in deep water is proportional to the square-root of it's wavelength, so these big waves are moving pretty fast and they just wouldn't be steep enough to carry you along with them. Also there's good reason to believe they're very short lived.
...directing photons in the case of the laser, or radio frequency energy in the case of the microwave...
So tell me again what radio waves are made of?
Fantastic, mind-boggling quote. Thanks!
...the mysterious dark matter that appears to be pushing regular matter around
That must be the extra mysterious version of dark matter that works opposite to gravity (pushes).
The normally mysterious version of dark matter is simply dark and mysterious. It pulls.
Consider the alternative phrasing: "relative speed". This is inferior to the given wording because it suggests that the speed of one was subtracted from the speed of the other, which is not the case for precisely the reasons you point out.
Furthermore, using simply "speed" is insufficient because it ignores the fact that both objects are moving.
Finally using "velocity" by itself suffers from the same problem as well as being non-specific with respect to direction.
In practice there is scientifically nothing wrong with giving the magnitude of velocity in this way. This is natural language after all, not an equation. If the reader doesn't understand the meaning, they've got bigger problems understanding the rest of it!
I think the size of the prototype is just right. The real breakthrough application area right now is camera phones. I have a camera on the back of my Sony Ericsson T610 that I've never used. Mobile phone cameras are held back by one massive obstacle: They're currently fixed zoom and fixed focus. Solve that cheaply and a truly massive market is ready made to adopt your solution.
Another fascinating application mentioned in NewScientist's coverage of this stuff is variable zoom security cameras. A security camera could zoom and focus selected portions of the field of view without needing to tilt or swivel the housing. Imagine a kind of moving fisheye effect within the rectangular frame of view. You bolt one of these very cheap cameras to the wall with a very wide field of view and then your operator/software invisibly controls the lens to follow objects closely. Awesome.
The bottomline line is that we don't need the big pharma companies to create either supply or demand for a drug.
Further proof, if we needed it, may be found by considering the ecstasy market.
Ah but you don't earn karma for funny mods.
Well I don't agree that stupid people should suffer, I do think this Sessions guy is culpable. His $330,000 not only ruined himself and his wife, it has kept the scammers going for years and years. How many more people will they scam on the back of that money?
I think anyone who responds to spam email (scams or otherwise) deserves to be strung up because it creates an atmosphere where that sort of thing is profitable.
Now this may be somewhat off-topic but I'm tired of people trying to use the front page of Slashdot to try to launch their favourite pet jargon. There is no such FLA as FAAQ. Why can't a single A service both "Asked" and "Anticipated"? I mean 4 FAAQ's sake!!
...may be errors in the above...
If you can't find a covering set, and for the remaining 11 numbers that looks most likely, then you're right, you can't know for sure that there is no prime.
There may be errors in the below too! You're assuming that there is no proof strategy alternative to covering sets. Maybe no one has thought of an alternative because covering sets have thus far shown the most promise?
Did anyone else notice the date in the corner of the image? It's Febuary 2002. I guess it takes a long time for this kind of reasearch to go from the lab to the media.
:)
The other way of doing it is basically the cold fusion method (call a press conference immediately). Pros and cons.
In python:
2 6708406385189575946388957261768583317 * \9 7116459852171130520711256363590397527
print 3980750864240649373971255005503864911990643623425
4727721461074353025362230719730482246329146953020
It gets better! 20996011 is necessarily prime as well. So, it's probably something like the 6 millionth prime, so you could store that using :)
only 22 bits! For further compression we'd probably have to prove the Riemann hypothesis.
Yes but it's easily compressible by representing it with the number 20996011 which can be stored using 25 bits. :)
probably give some nice images?!
You don't get 100 million euro devices built for the sake of some nice images. They're selling it on the idea of answering some of the fundamental questions about the universe. Like where do the high-energy cosmic rays come from? These are single protons with the energy of a driven golf ball and cannot be explained by current cosmology.
Also interesting to note is that they are planning to use the massive data network required to monitor other things like weather and seismic waves.
One thing that wasn't obvious from the article is that the antennae are not dishes. There are no moving parts. Dishes exist only in the central processor and are effectively CPU resources that can be assigned to multiple research groups simultaneously. If you double the capacity of the CPU, you double the number of virtual dishes available. Mind boggling.
Rotational force? Do you mean torque? Of course and equal and opposite torque is applied between the gyro and the bike, so what? I was talking about conservation of angular momentum.
Why don't you go outside, run and then lean over backwards. I don't know what that might prove but at least you'd probably hurt yourself.
One thing you are right about. If running at full throttle it will be dificult to break suddenly without using a flywheel. Air resistance would prove useful however in helping to tilt the bike backwards. Again this is exactly the same as a runner. It becomes more and more difficult to stop quickly from a sprint, not just because you're moving fast but because you can't get your feet in front of you. Wind drag at that speed allows 100m runners to begin braking.
Finally, humans do have a built in flywheel which is sometimes useful. When jumping through the air or balancing, people often rotate their arms opposite to the direction they are tipping.
A gyro can't just magically tilt the bike any which way. You have to have conservation of momentum. When the acceleration of the bike + the accel due to gravity does not line up with the line joining the ground contact with the centre of gravity, then the system is tipping and rotational inertia is being exchanged with the Earth. You can store some of this RI in a flywheel and then bleed it off later by tipping in the opposite direction. None of this is necessary to explain the braking mechanism though.
You are also dead wrong about the runner. A runner simply cannot lean over backwards quickly without the benefit of a flywheel (or a clothesline around the neck!). You need to get your feet out in front of you, which is achieved by moving them forward faster than your centre of gravity. This is basic classical mechanics, conservation of momentum, etc. I am actually a physicist.
It couldn't throw you backwards, the wheel speeds up until it's in front of you and then begins pushing you back to a stop. This is exactly what happens when you stop running, you have to first accelerate your feet until they're in front of you.
Bluetooth kills the battery life on my mobile phone so I never leave it switched on. It only takes a second to flip it on and off anyway...
Funny you should say that. I don't think nicotine is necessary to create addictive fast food. There is a growing body of evidence (har har) to support the position that fast food is already highly addictive because of the unnaturally sharp rush of sugar to the brain.
I was planning on buying the QuietComforts when I read this article. It convinced me of the merits of the Etymotic EP-4s especially as I wanted a highly portable solution. Most comparisons I've read say that the Etymotics win hands down as long as you don't mind sticking things into your ears. It's taken me a bit of getting used to but I love them.