I tried so hard to make this post short and simple and failed so badly, if you want you can just head to this wikipedia article on ionizing radiation or the epa's page on the topic and get a more coherent version of this post. Otherwise you can continue reading why the person who makes his money designing circuits that put radiation in the air thinks that radiation from electronics is safe.
Unfortunately very few people really know physics and very few people really know biology and especially since they are on somewhat opposite ends of the science spectrum an extremely small number of people really know both. This leads to a lot of confusion over how radiation impacts people.
I definitely can't claim to really know biology, but I do know some physics especially when it comes to a certain range of the electromagnetic spectrum. So I'm going to try to spread a bit of knowledge about the subject.
First of all, radiation sounds scary right? Well some of it is. If someone says there's a big source of alpha radiation near by then run. But when I tell you that in order to read this post you have to bombard your eyes with radiation and that each particle of that radiation is far more energetic than those created in a microwave, you should stay calm cause I'm talking about visible light.
Next an attempt to quickly explain what radiation is: radiation is a very general term describing particles or waves traveling through a medium. Unfortunately some radiation is described as waves while other radiation is described as particles and sometimes people go back and forth. Explaining that takes some mind bending quantum mechanics, but we can skip over that. Most of the time when radiation is discussed it's either alpha/beta radiation which is typically viewed as particles. In general big doses of alpha/beta radiation come from radioactive elements and can be scary stuff. The other type is electromagnetic radiation which is typically described as a wave. All electromagnetic radiation is the same thing, just with different frequencies. It's a bit easier to think of it as a particle in which case frequency describes how much energy each particle has and power describes how many of those particles are flying around. The span of frequencies is essentially infinite, but the range people typically encounter is about 10^6 Hz (AM radio) to 10^19 Hz (gamma rays - hopefully you don't encounter these too often). This chart from wikipedia nicely shows the spectrum. Notice that 10^6 to 10^19 is a crazy huge range - gamma radiation's frequency is 10 trillion times greater than the frequency of AM radio.
So what makes some radiation scary and some radiation completely safe? Well to answer that we have to know what it can do to a person. Alpha/beta/gamma radiation can do some really nasty stuff that can kill fairly quickly as well as cause cancer - I don't know much about what it is doing when it kills quickly - probably just messing up a bunch of molecules by knocking out electrons. The main fear of radiation is that it causes cancer. It can also heat the inside of the body.
Well what about cancer? Radiation causes cancer by knocking electrons out of molecules in DNA. Once an electron is knocked out it can change the chemical properties and change what the DNA encodes. Then a bunch of biology can happen and end up causing cancer. In order to knock out an electron the radiation particle hitting the electron must have enough energy to knock it out. The key here is that the individual particle must have enough energy. No matter how many times someone lightly pokes you, you'll never break a bone. So if the particles are low energy/low frequency it doesn't matter what the power is. If the particles do have enough energy then the power, and exposure time, do matter because the more particles hitting you the more likely one will hit an electron and cause all the steps required to cause cancer. This is the difference between ionizing and non-ionizing radiation and is the key concept in knowing how dangerous radiation is.
So what radiation is ionizing? Ultraviolet light and higher frequencies, so around 10^16 Hz and above. Cellphones, portable phones, wifi, baby monitors, and bluetooth all use frequencies around 10^8 to 10^10 Hz, one millionth the frequency of ionizing radiation. Most other electronic communication standards use lower frequencies cause generating higher frequencies is really hard. Note that visible light is between any radiation generated by electronics and the frequency of ionizing energy.
Ok, so all these electronics devices don't use ionizing radiation, but microwaves don't use ionizing radiation (2.4*10^9 Hz) and everyone knows that if they stick their head in a microwave bad stuff happens. True, this gets us to the third issue with radiation which is that it can heat parts of your body. Microwaves are the prime example of this since they are designed specifically to heat water, 2.4 GHz is the resonate frequency of water. The human body works really hard to keep its innards within a very specific range of temperatures and outside of that stuff starts to breakdown and cause problems. WiFi uses the same frequency as microwaves and cell phones are sorta close. So it seems reasonable that they could cause heating which would then cause issues. Except they don't put out nearly enough power. Try reheating leftovers by putting your cell phone next to them. A common response is even if the power is small, people spend a lot of time with cell phones next to their heads. True, but again the human body works really hard to keep its insides at the right temperature, so it's not going to have any problem adjusting to some tiny bit of power. Consider that the human body can handle it being 100 degrees outside or 0 degrees outside and still stay 98.6 degrees. Compared to that getting rid of the tiny bit of heat from cell phone radiation is nothing - heck getting rid of the heat from the hot phone touching your head is probably the bigger issue. Microwaves generate about 700 watts of radiation, cell phones max out around 2 watts.
Yeah you say all that, but what about those big studies that show that cellphones cause bad stuff? For that I refer you to my post about shoulder tapping.
A few bonus items:
-People who live near cell phone towers are actually exposed to less cell phone radiation. Most of the exposure is from their phone, which doesn't need to transmit as much power if it is close to a tower.
-If you notice that your ear feels kinda warm and weird after a long phone call on a cell phone, it isn't cause of the radiation, it's cause you were holding a hot, hard object against your ear for a long time. Normal phones have a more comfortable shape and don't get as hot.
If you're still worried about cell phone radiation:
-When you're talking the phone has to transmit a bunch of data so it is almost constantly sending out radiation. When you aren't talking it's just checking in with the tower every once in a while so the amount of radiation exposure is far lower.
-Radiation falls off with distance squared so moving the phone just a little further from your head significantly cuts down on the radiation, plus your ear will appreciate not being pressed against a hot object.
-Bluetooth only needs to cover from your ear to your phone, vs a phone that has to talk to a tower. So bluetooth head sets do transmit significantly less radiation.
-WiFi is actually the one that is the right frequency to heat water. But its range (and transmit power) is much less than a cell phone and people generally don't hold their computer or access point to their head. Sleeping near an access point isn't a big deal because there typically isn't a lot of traffic on your wireless network while you're asleep.
-It might seem that something like streaming a movie would cause more radiation from your phone/laptop because more data is moving over the wireless connection. But when downloading data the only transmitting the device needs to do is send acknowledgements that it's getting the data. That's more transmitting than when the device is doing nothing, but far less than if you're sending a movie to someone.
-Frequency, power and duration are all key to understanding the impacts of radiation so watch carefully what terms are being used when reading about the topic.
Thursday, December 16, 2010
Wednesday, December 15, 2010
Wikileaks
I probably shouldn't apologize every time I write a post that ends up too long, so this is me trying not to apologize even though I am sorry.
What I find so interesting about all the recent activity surrounding wikileaks is how it combines many of the social concepts associated with the internet.
One of the big memes when the intertubes first popped up and still one of the semi-utopian ideals of the internet is anonymity, summed up by the phrase on the internet nobody knows you're a dog. This sense of privacy has quickly eroded, but the internet is still a great way to get to interact with the world without anyone knowing who you are (if that no longer seems true, go check out TOR).
Another big meme which started long before the series of pipes and tubes was made, but was truly able to take off because of the internet is information wants to be free.
These two concepts are often promoted by the same people and organizations (such as The EFF, Richard Stallman, and to a much lesser degree myself). While it may be possible to mesh the two concepts into a consistent framework by drawing some lines, there's clearly some conflict between wanting transparency and privacy.
To me these have coexisted as two of the pillars of the social movement around the internet and the wikileaks events so nicely brings them out and especially their conflicts. Such as a secret organization, where one of the key enabling factors is their ability to give information sources complete anonymity, whose stated goal is increased transparency. Then a group that actually calls itself anonymous supports the group dedicated to transparency by disabling websites while ignoring the fact that shutting down websites is the opposite of promoting free speech.
This whole post so far is essentially a long drawn out version of this xkcd comic.
In addition to those two long standing concepts, a more recent idea comes into the picture. While net neutrality is typically discussed in relation to making sure ISPs treat everyone equally, the concept can also apply to webhosts refusing to host certain content. And even more disturbing, credit cards and paypal saying who you can and cannot pay using their services based on disapproving of what the organization says.
Another concept which I think is related to the idea that no one knows you're a dog is the idea that information should be put forward and evaluated on its own merits. I've mentioned this idea and its relationship to wikileaks before. This is one of the few concepts I'm mentioning that I am very wary of since I think that information without context can be misleading which is where experts can help clarify what the information actually means.
When the leaked documents first came out there was some commentary about it prompting security improvements. It is reasonably likely that wikileaks improved national security, because if they got the info then it seems reasonably likely that other nations and enemies of the state were already able to get it. But when wikileaks got the info the government found out so it is able to address the security weakness. There are a lot of existing computer security concepts related to this situation that I unfortunately don't know well enough to talk about (I know that usually doesn't stop me).
One thing I wonder is how the debate would change if instead of partially scrubbing the data, wikileaks was more like wikipedia and allowed the raw posted data to go up on the site. On one hand it seems much worse since potentially life threatening info could get out, but on the other hand it would make the poster responsible rather than the data hosting organization. Much like youtube isn't responsible if someone posts daily show episodes since they don't do anything to screen the posted content. Well ok, in the case of youtube they take down the offending material when contacted which of course wikileaks wouldn't do. Although by removing some of the data wikileaks is choosing what information to host and what information not to host much like what amazon did when they stopped hosting wikileaks. Holly crap, I'm now arguing that Assange isn't sufficiently dedicated to transparency, time to move along.
Anyway, kinda cool to see all those major concepts interacting over the course of a single news story, although it does make it really hard to come up with an opinion. But, I really think the reason this has become such a big story is that unlike the previous leak, no one knows who leaked the info. So everyone, including the government, is trying to place the blame somewhere. When the source of the leak is known it is so straight forward that the person who stole the info is guilty and having found the person to blame we can all just move along. But without that clear answer we get stuck in this area where all these normally great principals don't quite fit together.
What I find so interesting about all the recent activity surrounding wikileaks is how it combines many of the social concepts associated with the internet.
One of the big memes when the intertubes first popped up and still one of the semi-utopian ideals of the internet is anonymity, summed up by the phrase on the internet nobody knows you're a dog. This sense of privacy has quickly eroded, but the internet is still a great way to get to interact with the world without anyone knowing who you are (if that no longer seems true, go check out TOR).
Another big meme which started long before the series of pipes and tubes was made, but was truly able to take off because of the internet is information wants to be free.
These two concepts are often promoted by the same people and organizations (such as The EFF, Richard Stallman, and to a much lesser degree myself). While it may be possible to mesh the two concepts into a consistent framework by drawing some lines, there's clearly some conflict between wanting transparency and privacy.
To me these have coexisted as two of the pillars of the social movement around the internet and the wikileaks events so nicely brings them out and especially their conflicts. Such as a secret organization, where one of the key enabling factors is their ability to give information sources complete anonymity, whose stated goal is increased transparency. Then a group that actually calls itself anonymous supports the group dedicated to transparency by disabling websites while ignoring the fact that shutting down websites is the opposite of promoting free speech.
This whole post so far is essentially a long drawn out version of this xkcd comic.
In addition to those two long standing concepts, a more recent idea comes into the picture. While net neutrality is typically discussed in relation to making sure ISPs treat everyone equally, the concept can also apply to webhosts refusing to host certain content. And even more disturbing, credit cards and paypal saying who you can and cannot pay using their services based on disapproving of what the organization says.
Another concept which I think is related to the idea that no one knows you're a dog is the idea that information should be put forward and evaluated on its own merits. I've mentioned this idea and its relationship to wikileaks before. This is one of the few concepts I'm mentioning that I am very wary of since I think that information without context can be misleading which is where experts can help clarify what the information actually means.
When the leaked documents first came out there was some commentary about it prompting security improvements. It is reasonably likely that wikileaks improved national security, because if they got the info then it seems reasonably likely that other nations and enemies of the state were already able to get it. But when wikileaks got the info the government found out so it is able to address the security weakness. There are a lot of existing computer security concepts related to this situation that I unfortunately don't know well enough to talk about (I know that usually doesn't stop me).
One thing I wonder is how the debate would change if instead of partially scrubbing the data, wikileaks was more like wikipedia and allowed the raw posted data to go up on the site. On one hand it seems much worse since potentially life threatening info could get out, but on the other hand it would make the poster responsible rather than the data hosting organization. Much like youtube isn't responsible if someone posts daily show episodes since they don't do anything to screen the posted content. Well ok, in the case of youtube they take down the offending material when contacted which of course wikileaks wouldn't do. Although by removing some of the data wikileaks is choosing what information to host and what information not to host much like what amazon did when they stopped hosting wikileaks. Holly crap, I'm now arguing that Assange isn't sufficiently dedicated to transparency, time to move along.
Anyway, kinda cool to see all those major concepts interacting over the course of a single news story, although it does make it really hard to come up with an opinion. But, I really think the reason this has become such a big story is that unlike the previous leak, no one knows who leaked the info. So everyone, including the government, is trying to place the blame somewhere. When the source of the leak is known it is so straight forward that the person who stole the info is guilty and having found the person to blame we can all just move along. But without that clear answer we get stuck in this area where all these normally great principals don't quite fit together.
Tuesday, December 14, 2010
David's Second Rule for Debugging
Way back when I came up with David's Rule for Debugging, then read a book about debugging with a more comprehensive set of rules. Since then I've added a new rule to my list. The exact rule is still a bit of a work in progress, and it has some similarity to "get a fresh view", but I think has some unique aspects. So here it goes.
In its most extreme form the rule is:
I tried writing this post in a general way using third person but it was making it very tough to write so I'll just go with first person.
When I'm facing a problem, typically at first I'll want to think about it and look at it either on my own or as part of a small group. Later I might get around to "get a fresh perspective", but first I'll want a chance to get an understanding of the situation. This is especially true for high pressure/high excitement situations, which is unfortunate since that's when lots of people want to come by and get involved or give some advice. My general response is to try to gently push them away so I can get my chance to think/work (they typically don't leave, but I try).
However, there is a special case when the event is so high pressure and the results are so bad and make so little sense that the pressure gets to me and I start to feel nauseous. My gut reaction as the stress steps up is to push people away harder so I can dedicate my diminishing focus on the problem. But once nausea has kicked in there really isn't any focus or wits left to dedicate to the problem. That's when the rule kicks into effect, since I'm no longer of any use the best thing I can do is back away. Even if the people stopping by are normally less qualified to work on the problem, at this point random people off the street would have better luck solving it, so let them have at it. This also allows me to regain composure by stepping back rather than focusing in.
Luckily, I've only been in this situation once in recent memory and one of the people who stopped by was the exact right person to solve the problem. Unfortunately, I hadn't come up with this rule yet so I resisted help for longer than I should have, but eventually just had to back away. Also luckily, the person who solved the problem did it impressively quickly and once that was taken care of everything worked really well.
Can't say I'm looking forward to getting to use this rule, but at least if it happens I'll be prepared, well if I have enough wits left to use it - maybe the rule should be adjusted to: ...BEFORE you feel nauseous...
In its most extreme form the rule is:
If you feel nauseous or about to cry, let other people help you.
I tried writing this post in a general way using third person but it was making it very tough to write so I'll just go with first person.
When I'm facing a problem, typically at first I'll want to think about it and look at it either on my own or as part of a small group. Later I might get around to "get a fresh perspective", but first I'll want a chance to get an understanding of the situation. This is especially true for high pressure/high excitement situations, which is unfortunate since that's when lots of people want to come by and get involved or give some advice. My general response is to try to gently push them away so I can get my chance to think/work (they typically don't leave, but I try).
However, there is a special case when the event is so high pressure and the results are so bad and make so little sense that the pressure gets to me and I start to feel nauseous. My gut reaction as the stress steps up is to push people away harder so I can dedicate my diminishing focus on the problem. But once nausea has kicked in there really isn't any focus or wits left to dedicate to the problem. That's when the rule kicks into effect, since I'm no longer of any use the best thing I can do is back away. Even if the people stopping by are normally less qualified to work on the problem, at this point random people off the street would have better luck solving it, so let them have at it. This also allows me to regain composure by stepping back rather than focusing in.
Luckily, I've only been in this situation once in recent memory and one of the people who stopped by was the exact right person to solve the problem. Unfortunately, I hadn't come up with this rule yet so I resisted help for longer than I should have, but eventually just had to back away. Also luckily, the person who solved the problem did it impressively quickly and once that was taken care of everything worked really well.
Can't say I'm looking forward to getting to use this rule, but at least if it happens I'll be prepared, well if I have enough wits left to use it - maybe the rule should be adjusted to: ...BEFORE you feel nauseous...
Thursday, December 09, 2010
To Engineer Is Human
I finished up To Engineer Is Human a few weeks ago, but have been considering how to blog about it in the back of my head. It is a book from 1982 that is supposed to be about engineering in generally, but is almost entirely focused on structural engineering (and at the very end has a short chapter about using computer aided design). While it does have some general engineering lessons, it really isn't very relevant to pretty much anyone I know reading this blog. So while I'm tempted to dig into a bunch of examples in the book I'm going to try to just skim some highlights.
First off is he mentions The Deacon's Masterpiece which is one of the few engineering poems I've ever read. The poem itself is rather long, but the idea is that someone decides that for any wagon there's always one thing that breaks first. So he's going to design each piece of the wagon so it won't be the first to go. And the thing works great for years and years and eventually every part fails at once and the whole thing falls apart. It's pointing out that in any design, no matter how good there has to always be a weak point.
One of the main themes of the book is that the reliability of structures kind of goes in cycles. Once a type of bridge has been design properly with a certain set of materials so it doesn't fall one of a few things happen:
1. The same design is used in a different set of conditions and fails. Then the engineers figure out what is required for that set of conditions.
2. Lessons of the past are forgotten and repeated. Once the new bridge fails the lessons are remembered and the next set of bridges are good again.
3. Since the current bridges are good it is time for progress and new designs or new materials or the same idea but with less safety margin are used. Then if there are failures the issues are worked out and then some better reliable bridges are built.
Along similar lines he suggests that every design is a hypothesis. The hypothesis is the design will work without failure. When the hypothesis fails it can be very unfortunate, but it is also the most informative. When the structure doesn't fail it doesn't say much because who knows what slight change in conditions would cause it to fail.
The two themes above suggest the problem with using structural engineering to draw general lessons for all engineering. In many areas of engineering failure is not as catastrophic and as long as failure rates are within acceptable limits meeting performance requirements can be far more important.
A lot of the book is going through various structural failures and talking about why they happened. One of particular interest to me is the Kansas City Hyatt Walkway Failure. Less than a month after I was born the Kansas City Hyatt was hosting a large party, which some of my family members almost attended, and the walkways over the lobby where the party was held collapsed and killed 114 people. Some of the initial thoughts were that the walkways simply weren't designed for people dancing on them. What actually happened is that the original design used beams that stretched from the ceiling and each beam supported multiple levels of walkways. But getting bolts to the middle of a long beam was practically very difficult so someone modified the design to have one beam from ceiling to the top level and then another beam from the top walkway to the bottom walkway. The problem is that now the bolt holding the top walk way had to support the weight of two levels instead of just one. Besides the personal relevance of the story I think this is interesting because it is tempting to blame whoever made the change at the last minute. But it is also the fault of the original designer for creating a design that couldn't actually be built or as someone else put it:
Few other random items:
-Kind of cool to see a book from 1982 mention a congressman working on improving safety regulations and it's Al Gore.
-Excalibur and other sword myths have a lot to do with engineering (why when a bunch of swords are built one is especially reliable). So is Icarus (wings melting as he tried to fly to the sun) - this one is really about a good design being used improperly (for the SGU fans - get it, the Icarus planet, get it? - oh and for the SG1/SGA fans, Daedalus is the guy that built the wings). And the liberty bell is an engineering failure.
-In this book written in 1982:
-This one is actually an important lesson in many aspects of life - random failures can be mitigated by having two of something, but to backup against systematic failure the backup must be of a different design (a friend has a story about a bunch of people backpacking who all brought water pumps so they'd be ok if a few broke, but then the temperature dropped and all of the pumps froze - luckily some of them had iodine tablets).
Oh crap, so much for not writing too much. Sorry.
First off is he mentions The Deacon's Masterpiece which is one of the few engineering poems I've ever read. The poem itself is rather long, but the idea is that someone decides that for any wagon there's always one thing that breaks first. So he's going to design each piece of the wagon so it won't be the first to go. And the thing works great for years and years and eventually every part fails at once and the whole thing falls apart. It's pointing out that in any design, no matter how good there has to always be a weak point.
One of the main themes of the book is that the reliability of structures kind of goes in cycles. Once a type of bridge has been design properly with a certain set of materials so it doesn't fall one of a few things happen:
1. The same design is used in a different set of conditions and fails. Then the engineers figure out what is required for that set of conditions.
2. Lessons of the past are forgotten and repeated. Once the new bridge fails the lessons are remembered and the next set of bridges are good again.
3. Since the current bridges are good it is time for progress and new designs or new materials or the same idea but with less safety margin are used. Then if there are failures the issues are worked out and then some better reliable bridges are built.
Along similar lines he suggests that every design is a hypothesis. The hypothesis is the design will work without failure. When the hypothesis fails it can be very unfortunate, but it is also the most informative. When the structure doesn't fail it doesn't say much because who knows what slight change in conditions would cause it to fail.
The two themes above suggest the problem with using structural engineering to draw general lessons for all engineering. In many areas of engineering failure is not as catastrophic and as long as failure rates are within acceptable limits meeting performance requirements can be far more important.
A lot of the book is going through various structural failures and talking about why they happened. One of particular interest to me is the Kansas City Hyatt Walkway Failure. Less than a month after I was born the Kansas City Hyatt was hosting a large party, which some of my family members almost attended, and the walkways over the lobby where the party was held collapsed and killed 114 people. Some of the initial thoughts were that the walkways simply weren't designed for people dancing on them. What actually happened is that the original design used beams that stretched from the ceiling and each beam supported multiple levels of walkways. But getting bolts to the middle of a long beam was practically very difficult so someone modified the design to have one beam from ceiling to the top level and then another beam from the top walkway to the bottom walkway. The problem is that now the bolt holding the top walk way had to support the weight of two levels instead of just one. Besides the personal relevance of the story I think this is interesting because it is tempting to blame whoever made the change at the last minute. But it is also the fault of the original designer for creating a design that couldn't actually be built or as someone else put it:
A detail that begs a change cannot be completely without blame when the change is made.
Few other random items:
-Kind of cool to see a book from 1982 mention a congressman working on improving safety regulations and it's Al Gore.
-Excalibur and other sword myths have a lot to do with engineering (why when a bunch of swords are built one is especially reliable). So is Icarus (wings melting as he tried to fly to the sun) - this one is really about a good design being used improperly (for the SGU fans - get it, the Icarus planet, get it? - oh and for the SG1/SGA fans, Daedalus is the guy that built the wings). And the liberty bell is an engineering failure.
-In this book written in 1982:
Computer models that predict the behavior of the economy have come increasingly to be relied upon to justify major economic decisions, and yet these models are not necessarily any more infallible than the ones that predict the fatigue life of a bus frame.
-This one is actually an important lesson in many aspects of life - random failures can be mitigated by having two of something, but to backup against systematic failure the backup must be of a different design (a friend has a story about a bunch of people backpacking who all brought water pumps so they'd be ok if a few broke, but then the temperature dropped and all of the pumps froze - luckily some of them had iodine tablets).
Oh crap, so much for not writing too much. Sorry.
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