Someone who works in an office that processes all this stuff once told me that it is encrypted - but the password is the name of the office it's being sent to.
In Boscombe (and possibly other parts of Bournemouth) they have blue lights but I'm pretty sure they're not monochromatic. If you want that then bog standard low pressure sodium streetlights (the yellow ones) emit two wavelengths about 0.6 nm apart.
Tip-ring-sleeve connectors on devices for home use don't often carry both power and signal. The iPod Shuffle is an exception.
That and the 3.5mm jack plug when it's used for a PC microphone. Ground on the sleeve, signal on the tip, and +5 V on the ring connected through a 2.2 k resistor for current limiting).
Time is NOT a component of the "watts" unit. A watt is current times voltage And ampere's are charge per unit time (coulombs per second). If you work through the units voltage times charge has units of energy so voltage times current is in fact equivalent to energy over time.
The simple way of tapping a phone without extra voltage drop is to use a crystal earpiece. Connected in parallel with the line its high impedance causes no significant voltage drop and as such is totally undetectable. I have one with the wires soldered onto a pair of thin needles that can just be poked through the insulation on a phone line to contact the wires. With it I can hear everything said but the clicks when people hang up the phone and during ringing are painfully loud if it's in your ear at the time.
I'm currently second year physics in Exeter, UK. In the first year everyone covered the basics of matlab. In the second year there was a choice between an several modules including electronics and scientific programming in C with the option to do a further module, in Computational Physics. Neither of the C modules were a requirement though - I ended up doing electronics instead but I have an option to do the first C module next year (I think).
The 100m limit is actually a problem with the delay from one end to the other messing with the collision detection rather than with signal strength. With a switch on each end (as opposed to a simple hub) you eliminate that problem (by eliminating any chance of a collision) and can stretch it further. Not sure if it'd make 500m though.
There is a 60 Hz variant of PAL, I believe it's used in Brazil. Oddly I find a c.r.t. monitor at 60 Hz annoying but a c.r.t. television at 50 Hz doesn't bother me. I think the TVs must use different phosphors with longer persistence. At least we don't get the 3:2 pulldown when watching movies that were shot at 24 frames per second (we just watch them 4% faster).
Something similar happens with coal or oil fired stations - the air intake fans use synchronous motors so their speed is directly linked to the grid frequency. If the load on the system increases without being matched by more generating capacity that frequency drops slowing the fans and reducing the intake air. With less air they can't burn as much fuel and hence produce less power making the problem worse. Below a certain frequency the system cannot recover and shuts down. Automated load shedding and similar is set to operate before this point - in the UK there is a total of 2.5GW that will be automatically shed if the frequency drops below 49.8 Hz (nominal frequency 50 Hz) This is from a peak demand of 60GW. See the wikipedia page for more details.
PET scans do involve ionizing radiation, not from the machine itself but from a radioisotope such as carbon-11 which is injected into the test subject. It emits positrons when it decays which are directly ionizing in the same way as beta radiation. The positrons then annihilate with electrons producing a pair of 511 keV gamma photons. The gamma radiation is also ionizing.
With regard to the cell phones the suggested mechanism is localized heating of the tissues near to the antenna which is possible but wouldn't necessarily cause cancer.
I study physics at Exeter university in the UK and several of my lecturers have been researching the structures which produce the colours in butterflies (and some other animals such as beetles). See this page on natural photonics for more details.
Of course in the UK this is pretty much a non-issue. There are fuses in the plugs which protect the cable from overheating if someone puts a big heater or something on a wimpy 5 amp cable (the lowest rating I've seen on an extension lead). It can still be a problem with cables that are tightly coiled up and can't dissipate the heat so well but in general the worst that happens if someone overloads an extension lead is the fuse blows.
Of course the higher voltage helps as well by reducing the current the cables need to carry. Over here they typically state the maximum current they can take and I've seen one with two ratings marked on it - one for with the lead coiled up and one for fully uncoiled. Conductor sizes and voltage ratings are commonly be molded into the cable insulation though.
I have a compaq armada that runs mains to the laptop. Gets very hot thanks to that internal PSU but I don't use it anymore anyway. Power input is a 3 pin cloverleaf connector.
While there is a limit on the maximum velocity the particles can obtain, the temperature actually depends on the kinetic energy of the particles which does not (so far as anyone knows) have a limit. This is because the mass of the particles increases as they are accelerated to the speed of light. The explanation of maximum temperature in terms of the speed of light sounds nice at first and it was one of the first things I thought of but the physics doesn't really work like that.
1. That could glow pretty bright in the night sky. Environmentalists may complain.
Only if they can see microwaves.
I assumed he was referring to the reflected sunlight from such a large area of solar panels, in the same way that current satellites are visible in the night sky but much brighter due to its size (the Iridium communications satellites are particularly well known for this). I don't see it as being a big issue though.
so are you telling me that if I throw a fluorescent light at a power line it will glow?
Not quite. Hold one end of the tube, point the other end at the line. Needs to be one of the higher voltage ones cos experience shows that 11kV doesn't cut it (although it might work if the lines were really close to the ground, depends on the electrostatic field in Volts per meter). The tube will light but not that brightly so you'll have to do it at night for it to be visible. Ever see this photo?
There's a bridge near where I live (Southampton, UK) like that. It got hit 3 times in one year and because it goes across the road at an angle the lorries tend to roll over and get jammed under the bridge at about 45 degrees with one side up in the air. It's a big pain in the arse cos every time it happens they have to close the bridge to train going over it until it's been inspected to check the bridge is still structurally sound. They now have a big metal bar in place that they hit to prevent damaging the bridge but it still rolls them over. A photo before the steel barrier was added
My father knows one of the drivers who's hit it. Apparently he was making a delivery and he wasn't sure if there was enough room so he pulled over, checked, and edged very slowly under the bridge with about 4 inches of clearance. On his way back he'd already been under the bridge so he was certain there was room so he drove straight under. Only problem was he'd unloaded and the lorry had risen on its suspension due to the lost weight.
this sounds like something that hasn't been cracked purely by laziness, because with only 256 possible combinations you could practically decode it in real time in your head.
I was thinking pretty much the same thing. In the article it says "256 key combination can be brute forced even with very slow computers today." when "any idiot with half an hour and a pencil" would perhaps be more appropriate.
My university (Exeter, UK) has a policy that "University business should only be conducted using University e-mail accounts (so that it is possible to track whether a message has been sent or received)." Everyone is given an email address based on their username @exeter.ac.uk or @ex.ac.uk (we can use either/both, it seems to be common for universities in the UK to have two domains, a full name and an abbreviated one).
Up until a few years ago everyone had the system you described (06jdoe@...), or something similar at least, however that's been changed due to the number of students with the same names. It's now one based on initials and year with an extra number to differentiate those with the same initials. Mine is rsc206 (second person in 2006 with initials rsc), except my actual initials are R.C.S so clearly there was a typo in there somewhere.
Old accounts still exist and staff seem to get [initial].lastname@...
Except for the electronic ignition controlling the spark and the electronic power regulation keeping the alternator at 13.5v.
The regulator failing wouldn't stop the car (at least not quickly anyway). Either it'd fail open circuit and the alternator would stop producing power in which case the engine would run happily for several hours with the battery powering the ignition (less time if there are other loads e.g. lights). OR it would fail closed circuit and dump the full current into the alternator field coils. In this case the voltage would go up but probably not much past 15 or 16 Volts as large currents would flow into the battery keeping the voltage from rising too high. Battery and alternator would heat up and eventually one of the two be damaged but again this could take an hour or so.
You could go one step further than that. Resistive loads can run on d.c. and many switching power supplies (not all though by a long means) are happy with anything a.c. or d.c. between 90 and 250 Volts. Universal motors, which as you mention are common in power tools etc, also run well on d.c. This is useful because certain kinds of d.c. to d.c. converters can be more efficient than square wave inverters.
That story makes me think of Marc Emery - he's been putting "Marijuana seed vendor" on his tax returns for years (This is in Canada where it's technically illegal but rarely enforced). Unfortunatly the US authorities are currently trying to get him extridited.
Work it out if you really want to know but it's not a problem, even if pi were needed to make the sphere which it isn't. I remember readong somewhere a while ago (it may have been on slashdot, may have been somewhere else) that 34 decimal places of pi are sufficient to calculate the radius of the uiverse to within the width of a hydrogen atom.
It's fairly easy to prove that this is roughly correct if you look up the the two sizes. Compare the orders of magnitude.
Slashdot Mirror
Someone who works in an office that processes all this stuff once told me that it is encrypted - but the password is the name of the office it's being sent to.
In Boscombe (and possibly other parts of Bournemouth) they have blue lights but I'm pretty sure they're not monochromatic. If you want that then bog standard low pressure sodium streetlights (the yellow ones) emit two wavelengths about 0.6 nm apart.
Tip-ring-sleeve connectors on devices for home use don't often carry both power and signal. The iPod Shuffle is an exception.
That and the 3.5mm jack plug when it's used for a PC microphone. Ground on the sleeve, signal on the tip, and +5 V on the ring connected through a 2.2 k resistor for current limiting).
The simple way of tapping a phone without extra voltage drop is to use a crystal earpiece. Connected in parallel with the line its high impedance causes no significant voltage drop and as such is totally undetectable. I have one with the wires soldered onto a pair of thin needles that can just be poked through the insulation on a phone line to contact the wires. With it I can hear everything said but the clicks when people hang up the phone and during ringing are painfully loud if it's in your ear at the time.
I'm currently second year physics in Exeter, UK. In the first year everyone covered the basics of matlab. In the second year there was a choice between an several modules including electronics and scientific programming in C with the option to do a further module, in Computational Physics. Neither of the C modules were a requirement though - I ended up doing electronics instead but I have an option to do the first C module next year (I think).
The 100m limit is actually a problem with the delay from one end to the other messing with the collision detection rather than with signal strength. With a switch on each end (as opposed to a simple hub) you eliminate that problem (by eliminating any chance of a collision) and can stretch it further. Not sure if it'd make 500m though.
There is a 60 Hz variant of PAL, I believe it's used in Brazil. Oddly I find a c.r.t. monitor at 60 Hz annoying but a c.r.t. television at 50 Hz doesn't bother me. I think the TVs must use different phosphors with longer persistence. At least we don't get the 3:2 pulldown when watching movies that were shot at 24 frames per second (we just watch them 4% faster).
Something similar happens with coal or oil fired stations - the air intake fans use synchronous motors so their speed is directly linked to the grid frequency. If the load on the system increases without being matched by more generating capacity that frequency drops slowing the fans and reducing the intake air. With less air they can't burn as much fuel and hence produce less power making the problem worse. Below a certain frequency the system cannot recover and shuts down. Automated load shedding and similar is set to operate before this point - in the UK there is a total of 2.5GW that will be automatically shed if the frequency drops below 49.8 Hz (nominal frequency 50 Hz) This is from a peak demand of 60GW. See the wikipedia page for more details.
PET scans do involve ionizing radiation, not from the machine itself but from a radioisotope such as carbon-11 which is injected into the test subject. It emits positrons when it decays which are directly ionizing in the same way as beta radiation. The positrons then annihilate with electrons producing a pair of 511 keV gamma photons. The gamma radiation is also ionizing.
With regard to the cell phones the suggested mechanism is localized heating of the tissues near to the antenna which is possible but wouldn't necessarily cause cancer.
I study physics at Exeter university in the UK and several of my lecturers have been researching the structures which produce the colours in butterflies (and some other animals such as beetles). See this page on natural photonics for more details.
Of course in the UK this is pretty much a non-issue. There are fuses in the plugs which protect the cable from overheating if someone puts a big heater or something on a wimpy 5 amp cable (the lowest rating I've seen on an extension lead). It can still be a problem with cables that are tightly coiled up and can't dissipate the heat so well but in general the worst that happens if someone overloads an extension lead is the fuse blows.
Of course the higher voltage helps as well by reducing the current the cables need to carry. Over here they typically state the maximum current they can take and I've seen one with two ratings marked on it - one for with the lead coiled up and one for fully uncoiled. Conductor sizes and voltage ratings are commonly be molded into the cable insulation though.
I have a compaq armada that runs mains to the laptop. Gets very hot thanks to that internal PSU but I don't use it anymore anyway. Power input is a 3 pin cloverleaf connector.
While there is a limit on the maximum velocity the particles can obtain, the temperature actually depends on the kinetic energy of the particles which does not (so far as anyone knows) have a limit. This is because the mass of the particles increases as they are accelerated to the speed of light. The explanation of maximum temperature in terms of the speed of light sounds nice at first and it was one of the first things I thought of but the physics doesn't really work like that.
Only if they can see microwaves.
I assumed he was referring to the reflected sunlight from such a large area of solar panels, in the same way that current satellites are visible in the night sky but much brighter due to its size (the Iridium communications satellites are particularly well known for this). I don't see it as being a big issue though.
Yeah, it's the same concept but since the frequency of a Tesla coil is much higher the capacitive coupling would be much more effective.
Not quite. Hold one end of the tube, point the other end at the line. Needs to be one of the higher voltage ones cos experience shows that 11kV doesn't cut it (although it might work if the lines were really close to the ground, depends on the electrostatic field in Volts per meter). The tube will light but not that brightly so you'll have to do it at night for it to be visible. Ever see this photo?
The is no more to say. The world has ended. With luck there will be beer!
(Seriously, when I saw those two on the front page my first reaction was WTF)
There's a bridge near where I live (Southampton, UK) like that. It got hit 3 times in one year and because it goes across the road at an angle the lorries tend to roll over and get jammed under the bridge at about 45 degrees with one side up in the air. It's a big pain in the arse cos every time it happens they have to close the bridge to train going over it until it's been inspected to check the bridge is still structurally sound. They now have a big metal bar in place that they hit to prevent damaging the bridge but it still rolls them over. A photo before the steel barrier was added
My father knows one of the drivers who's hit it. Apparently he was making a delivery and he wasn't sure if there was enough room so he pulled over, checked, and edged very slowly under the bridge with about 4 inches of clearance. On his way back he'd already been under the bridge so he was certain there was room so he drove straight under. Only problem was he'd unloaded and the lorry had risen on its suspension due to the lost weight.
I was thinking pretty much the same thing. In the article it says "256 key combination can be brute forced even with very slow computers today." when "any idiot with half an hour and a pencil" would perhaps be more appropriate.
My university (Exeter, UK) has a policy that "University business should only be conducted using University e-mail accounts (so that it is possible to track whether a message has been sent or received)." Everyone is given an email address based on their username @exeter.ac.uk or @ex.ac.uk (we can use either/both, it seems to be common for universities in the UK to have two domains, a full name and an abbreviated one).
Up until a few years ago everyone had the system you described (06jdoe@...), or something similar at least, however that's been changed due to the number of students with the same names. It's now one based on initials and year with an extra number to differentiate those with the same initials. Mine is rsc206 (second person in 2006 with initials rsc), except my actual initials are R.C.S so clearly there was a typo in there somewhere.
Old accounts still exist and staff seem to get [initial].lastname@...
The regulator failing wouldn't stop the car (at least not quickly anyway). Either it'd fail open circuit and the alternator would stop producing power in which case the engine would run happily for several hours with the battery powering the ignition (less time if there are other loads e.g. lights). OR it would fail closed circuit and dump the full current into the alternator field coils. In this case the voltage would go up but probably not much past 15 or 16 Volts as large currents would flow into the battery keeping the voltage from rising too high. Battery and alternator would heat up and eventually one of the two be damaged but again this could take an hour or so.
You could go one step further than that. Resistive loads can run on d.c. and many switching power supplies (not all though by a long means) are happy with anything a.c. or d.c. between 90 and 250 Volts. Universal motors, which as you mention are common in power tools etc, also run well on d.c. This is useful because certain kinds of d.c. to d.c. converters can be more efficient than square wave inverters.
That story makes me think of Marc Emery - he's been putting "Marijuana seed vendor" on his tax returns for years (This is in Canada where it's technically illegal but rarely enforced). Unfortunatly the US authorities are currently trying to get him extridited.
Work it out if you really want to know but it's not a problem, even if pi were needed to make the sphere which it isn't. I remember readong somewhere a while ago (it may have been on slashdot, may have been somewhere else) that 34 decimal places of pi are sufficient to calculate the radius of the uiverse to within the width of a hydrogen atom.
It's fairly easy to prove that this is roughly correct if you look up the the two sizes. Compare the orders of magnitude.