Security Analysis of a Full-Body Scanner(radsec.org)
radsec.org
Security Analysis of a Full-Body Scanner
https://radsec.org/
7 comments
If the attack you are worried about is terrorism (which I imagine it must be, since that's the thing these things purport to stop, I suppose), then I don't think this is a big problem. Terrorists get about as much bang for their buck whether or not they get caught, so they can presumably just try out their strategies a few times and see if they get caught.
These machines are such a blatant violation of our Constitutional rights. We shouldn't be searched like this without probable cause or a search warrant. Whether they are effective or not is irrelevant.
They aren't a violation when you can ALWAYS "opt out" and get a pat down.
Whether a pat down is a rights violation is another question, but I think that mandatory searches for safety reasons have long passed Supreme Court tests.
Whether a pat down is a rights violation is another question, but I think that mandatory searches for safety reasons have long passed Supreme Court tests.
We don't have a constitution.
(Not everyone on the internet is American, and of those who are, none can do anything about erosion of your rights. Complain to your local political representative, who potentially can).
(Not everyone on the internet is American, and of those who are, none can do anything about erosion of your rights. Complain to your local political representative, who potentially can).
Sorry for the US-centric comment. All people are created equal with unalienable rights, so we shouldn't be trampling the human rights of foreigners either. It's just easier to point out the abuses when we have governing documents that explicitly say we shouldn't be doing the thing that we're doing.
> It's just easier to point out the abuses when we have governing documents that explicitly say we shouldn't be doing the thing that we're doing.
Can you explain what part of it is unconstitutional? Because while I'm totally against it, I think it is pretty much entirely constitutional because airlines are a private business that no one is being forced to go through. But I clearly don't know much about this and would welcome an education.
Can you explain what part of it is unconstitutional? Because while I'm totally against it, I think it is pretty much entirely constitutional because airlines are a private business that no one is being forced to go through. But I clearly don't know much about this and would welcome an education.
Earlier this year, the ACLU won a case regarding the constitutionally of the no-fly list[1]. Basically, their argument was that you can't give up your Fifth Amendment rights (due process) when you travel internationally. Since this argument won, it implies that Fourth Amendment rights (probable cause searches) also cannot be forfeited.
Relevant quote:
"Accordingly, the Court concludes on this record that Plaintiffs have a constitutionally-protected liberty interest in traveling internationally by air, which is affected by being placed on the No Fly List." [2]
[1] - https://www.aclu.org/national-security/latif-et-al-v-holder-...
[2] - https://www.aclu.org/sites/default/files/assets/latif_v_hold...
Relevant quote:
"Accordingly, the Court concludes on this record that Plaintiffs have a constitutionally-protected liberty interest in traveling internationally by air, which is affected by being placed on the No Fly List." [2]
[1] - https://www.aclu.org/national-security/latif-et-al-v-holder-...
[2] - https://www.aclu.org/sites/default/files/assets/latif_v_hold...
The Fourth Amendment only protects against unreasonable searches without probable cause. The Supreme Court could well decide that airport scanners are reasonable and therefore do not require probable cause.
The TSA is a government agency, not a private organization. Options for flying without undergoing a grope down or subjecting oneself to the nudie photo maker are limited to those wealthy enough to fly private.
> The TSA is a government agency, not a private organization.
Right, but the airlines are private and you are choosing to enter into a contract with them out of your own volition. The TSA is a regulator, but is not requiring that you fly.
> Options for flying without undergoing a grope down or subjecting oneself to the nudie photo maker are limited to those wealthy enough to fly private.
Which sucks, but doesn't sound like a constitutional violation to me.
Right, but the airlines are private and you are choosing to enter into a contract with them out of your own volition. The TSA is a regulator, but is not requiring that you fly.
> Options for flying without undergoing a grope down or subjecting oneself to the nudie photo maker are limited to those wealthy enough to fly private.
Which sucks, but doesn't sound like a constitutional violation to me.
Freedom of movement is considered a constitutional right. http://en.wikipedia.org/wiki/Freedom_of_movement_under_Unite... If you live in a remote area where the only option is to fly commercial you may have a strong case.
However, my understand is these are only added to major airports to avoid encountering such a situation. As you don't need to fly to get from Chicago or NY to just about anywhere.
Which creates another issue. Your not re-screened after traveling from a minor to a major airport which renders these precautions practically useless vs an intelligent advisory.
However, my understand is these are only added to major airports to avoid encountering such a situation. As you don't need to fly to get from Chicago or NY to just about anywhere.
Which creates another issue. Your not re-screened after traveling from a minor to a major airport which renders these precautions practically useless vs an intelligent advisory.
> Current US Code addresses air travel specifically. In 49 U.S.C. § 40103, "Sovereignty and use of airspace", the Code specifies that "A citizen of the United States has a public right of transit through the navigable airspace."
This doesn't sound like guaranteed use of commercial airports/airlines, it sounds like you'd have the right to fly yourself from your own airstrip, but not necessarily from an airport.
> Which creates another issue. As your not re-screened after traveling from a minor to a major airport which renders these precautions practically useless vs an intelligent advisory.
That is interesting.
This doesn't sound like guaranteed use of commercial airports/airlines, it sounds like you'd have the right to fly yourself from your own airstrip, but not necessarily from an airport.
> Which creates another issue. As your not re-screened after traveling from a minor to a major airport which renders these precautions practically useless vs an intelligent advisory.
That is interesting.
"The right to travel is a part of the 'liberty' of which the citizen cannot be deprived without due process of law under the Fifth Amendment. If that "liberty" is to be regulated, it must be pursuant to the law-making functions of the Congress. . . . . Freedom of movement across frontiers in either direction, and inside frontiers as well, was a part of our heritage. Travel abroad, like travel within the country, . . . may be as close to the heart of the individual as the choice of what he eats, or wears, or reads. Freedom of movement is basic in our scheme of values." - Justice William O. Douglas
Like everything there is a balancing act between the interests of the individual, group, and state. One can argue that commercial air travel is so important to modern travel and movement of people (are you going to take a boat to Hawaii?) that going through needlessly invasive screening without any suspicion or probable cause as a prerequisite might be an undue limit on freedom of movement.
Like everything there is a balancing act between the interests of the individual, group, and state. One can argue that commercial air travel is so important to modern travel and movement of people (are you going to take a boat to Hawaii?) that going through needlessly invasive screening without any suspicion or probable cause as a prerequisite might be an undue limit on freedom of movement.
The supreme court ruled 8-1 that strip searches in schools are unconstitutional. How are technology-enabled strip searches at the airport any different?
Link: http://www.washingtonpost.com/wp-dyn/content/article/2009/06...
Link: http://www.washingtonpost.com/wp-dyn/content/article/2009/06...
> The supreme court ruled 8-1 that strip searches in schools are unconstitutional.
They have not. You'll have to point to a specific case because they have ruled for strip searches to be constitutional under essentially what amounts to probable cause.
Edit: you added the link. If the girl in that story had been using or distributing an illegal drug it would've been a (legally) reasonable search: http://en.wikipedia.org/wiki/New_Jersey_v._T._L._O.
> How are technology-enabled strip searches at the airport any different?
Putting aside the question of whether or not MMW scans are actually legally equivalent to strip searches, the government forces you to show up to school. It does not force you to show up to the airport.
They have not. You'll have to point to a specific case because they have ruled for strip searches to be constitutional under essentially what amounts to probable cause.
Edit: you added the link. If the girl in that story had been using or distributing an illegal drug it would've been a (legally) reasonable search: http://en.wikipedia.org/wiki/New_Jersey_v._T._L._O.
> How are technology-enabled strip searches at the airport any different?
Putting aside the question of whether or not MMW scans are actually legally equivalent to strip searches, the government forces you to show up to school. It does not force you to show up to the airport.
No, "the court ruled 8 to 1 that such an intrusive search without the threat of a clear danger to other students violated the Constitution's protections against unreasonable search or seizure".
How would her having illegal drugs be a clear danger to other students?
How would her having illegal drugs be a clear danger to other students?
No what? Nothing I said disagrees with that.
Can we go back to the part where you explain how scanners at airports are a "blatant violation of our Constitutional rights"?
Can we go back to the part where you explain how scanners at airports are a "blatant violation of our Constitutional rights"?
To be fair this paper is about machines deployed by the TSA.
Hi! Lead author here.
We'll be giving a talk on this work tomorrow at the USENIX Security, but I'm happy to answer any questions you have here before then.
We'll be giving a talk on this work tomorrow at the USENIX Security, but I'm happy to answer any questions you have here before then.
Theoretically, how many of these (or similar) techniques would work against the millimeter wave scanners currently deployed in US airports?
We don't have one of those machines to test on, so we can't say for sure.
We think it's likely that they went through the same sort of evaluation process that put the Secure 1000 into service, and that they should be publicly reviewed by independent researchers.
We think it's likely that they went through the same sort of evaluation process that put the Secure 1000 into service, and that they should be publicly reviewed by independent researchers.
Don't the millimeter wave machines perform a 360 degree scan? That would at least eliminate the really facepalm-inducing "put your gun on the side of your body" attack.
Doesn't seem that way. The sensor revolves around the subject being scanned, but the images that have always been shown as coming from the machine are just front and back images.
From L3's sales site for the ProVision MMW machine, sample images:
http://storage.pardot.com/16582/23361/product_provision_L_3_...
Their "ATD" model that includes image analysis to automatically flag "anomalies" only seems to show front and back, too.
http://storage.pardot.com/16582/23381/products_ait_ProVision...
In 2012, the "TSA Out Of Our Pants" guy previously documented the "conceal a metal object on the side of your body" attack, and did so against the MMW machines with the ATD software on them:
http://tsaoutofourpants.wordpress.com/2012/03/06/1b-of-nude-...
From L3's sales site for the ProVision MMW machine, sample images:
http://storage.pardot.com/16582/23361/product_provision_L_3_...
Their "ATD" model that includes image analysis to automatically flag "anomalies" only seems to show front and back, too.
http://storage.pardot.com/16582/23381/products_ait_ProVision...
In 2012, the "TSA Out Of Our Pants" guy previously documented the "conceal a metal object on the side of your body" attack, and did so against the MMW machines with the ATD software on them:
http://tsaoutofourpants.wordpress.com/2012/03/06/1b-of-nude-...
Interesting. I always assumed it was doing a 360 scan. The sample images do seem to hint at a 2D scan, though the ATD front & back cartoon should be enough to highlight anomalies anywhere on the traveler's body.
It's too bad the "TSA Out Of Our Pants" guy didn't have a hidden camera accomplice to film his entire trip through security.
It's too bad the "TSA Out Of Our Pants" guy didn't have a hidden camera accomplice to film his entire trip through security.
As everyone knows, they aren't there for security.
They are there for theater.
Meanwhile the number of TSA "officers" arrested continues to grow each month http://tsascandals.wordpress.com/
They are there for theater.
Meanwhile the number of TSA "officers" arrested continues to grow each month http://tsascandals.wordpress.com/
I always opt out for this reason, even when I'm risking missing my plane. Paying contractors a lot of taxpayer money for a public placebo is offensive, and this makes me feel true to myself, but I wish I knew a more effective method of protesting. Currently no one really wonders about the odd out-out.
They removed these machines from airports in 2013 but are still using them elsewhere - prisons, gov't offices. So while you may not be able to bomb a plane, you can still take a gun into court. Lovely!
The airports I frequent (in particular San Jose International) are very much still using full-body scanners.
Edit: Do you mean this particular model is no longer in use? If so, are newer models not susceptible to these attacks?
Edit: Do you mean this particular model is no longer in use? If so, are newer models not susceptible to these attacks?
Backscatter x-ray technology was removed from airports. [1]
All airports now use millimeter wave technology. [2]
[1] https://en.wikipedia.org/wiki/Backscatter_X-ray
[2] https://en.wikipedia.org/wiki/Millimeter_wave_scanner
All airports now use millimeter wave technology. [2]
[1] https://en.wikipedia.org/wiki/Backscatter_X-ray
[2] https://en.wikipedia.org/wiki/Millimeter_wave_scanner
Millimeter wave scanners still subject the body to radiation, even though they don't have the work "X-Ray" in the name. Radiation damage to your body is cumulative throughout your life, so if you care about your longevity, you'd be wise to opt-out of subjecting your body to this radiation whenever possible.
So you've got a bunch of responses, but as a guy with a Master's in applied physics I wanted to chime in with a bit more of a long explanation.
The word "radiation" just means that something radiates -- it travels off to infinity. In this case we're talking about electromagnetic radiation, which spans a vast continuum from radio waves through microwaves to infrared and red, across the visible spectrum to deep blue, then on into ultraviolet, X-ray, and gamma light. It turns out that this radiation is quantized -- meaning it comes in lumps of a certain energy E = hf where h is a fundamental constant and f is the frequency of the light (equivalently, f = c / L where L is the wavelength). Light also comes with a certain "kick" or momentum p = E / c. We knew the latter formula from classical electromagnetism but the former formula was awarded two Nobel prizes, one to Max Planck and one three years later to Albert Einstein.
It is presently thought that the blue side of the non-visible electromagnetic radiation spectrum (UV, X-rays, Gamma rays) is cancer-causing, while the visible and red-side of nonvisible is not. This comports with the Planck/Einstein law for the energy of the photons, which approaches the bond energies for several common atomic bonds in the visible spectrum and exceeds it as we go into the ultraviolet. (We essentially see light by having the light excite these bonds, but not so much that it tears them apart, so as they "relax" to their starting configuration they release the energy and activate neurons.)
Microwaves are about 1mm or 1cm long, on the red side. They are emitted by microwave ovens, cell phones, wifi hotspots, and millimeter-wave detectors. Right now it's not thought that these are "dangerous" radiation any more than white light is, because their "kicks" don't excite the atomic bonds but are instead absorbed by proteins as a whole, in a process we presently think is indistinguishable from any other sort of heat transfer. That is, they heat you up, but don't do much else.
If they did something else, probably very large changes would have to be made to our modern scientific understanding, which I of course would totally support if experiments bore it out. At present there are no good experiments which show any other effects of microwaves on biological tissue, other than the heating thing.
The word "radiation" just means that something radiates -- it travels off to infinity. In this case we're talking about electromagnetic radiation, which spans a vast continuum from radio waves through microwaves to infrared and red, across the visible spectrum to deep blue, then on into ultraviolet, X-ray, and gamma light. It turns out that this radiation is quantized -- meaning it comes in lumps of a certain energy E = hf where h is a fundamental constant and f is the frequency of the light (equivalently, f = c / L where L is the wavelength). Light also comes with a certain "kick" or momentum p = E / c. We knew the latter formula from classical electromagnetism but the former formula was awarded two Nobel prizes, one to Max Planck and one three years later to Albert Einstein.
It is presently thought that the blue side of the non-visible electromagnetic radiation spectrum (UV, X-rays, Gamma rays) is cancer-causing, while the visible and red-side of nonvisible is not. This comports with the Planck/Einstein law for the energy of the photons, which approaches the bond energies for several common atomic bonds in the visible spectrum and exceeds it as we go into the ultraviolet. (We essentially see light by having the light excite these bonds, but not so much that it tears them apart, so as they "relax" to their starting configuration they release the energy and activate neurons.)
Microwaves are about 1mm or 1cm long, on the red side. They are emitted by microwave ovens, cell phones, wifi hotspots, and millimeter-wave detectors. Right now it's not thought that these are "dangerous" radiation any more than white light is, because their "kicks" don't excite the atomic bonds but are instead absorbed by proteins as a whole, in a process we presently think is indistinguishable from any other sort of heat transfer. That is, they heat you up, but don't do much else.
If they did something else, probably very large changes would have to be made to our modern scientific understanding, which I of course would totally support if experiments bore it out. At present there are no good experiments which show any other effects of microwaves on biological tissue, other than the heating thing.
Thanks for the reply. I don't know if wikipedia is the best source, but talking about health risks, it states:
> A team led by Los Alamos National Labs found that although the forces that terahertz waves exert on double-stranded DNA are tiny, in certain circumstances resonant effects can unzip the DNA strands, tearing them apart. This creates bubbles in the strands that can significantly interfere with processes such as gene expression and DNA replication. [1]
Unzipping DNA strands in certain circumstances sounds pretty harmful.
I understand theoretically why millimeter waves are lower risk than backscatter x-rays, but it seems to me that there still are risks. In my opinion, before sending the population through these things, we need studies of their long-term effects from real-world exposure, not just theoretical reasoning about why the rays are most likely safe.
[1] https://en.wikipedia.org/wiki/Millimeter_wave_scanner#Possib...
> A team led by Los Alamos National Labs found that although the forces that terahertz waves exert on double-stranded DNA are tiny, in certain circumstances resonant effects can unzip the DNA strands, tearing them apart. This creates bubbles in the strands that can significantly interfere with processes such as gene expression and DNA replication. [1]
Unzipping DNA strands in certain circumstances sounds pretty harmful.
I understand theoretically why millimeter waves are lower risk than backscatter x-rays, but it seems to me that there still are risks. In my opinion, before sending the population through these things, we need studies of their long-term effects from real-world exposure, not just theoretical reasoning about why the rays are most likely safe.
[1] https://en.wikipedia.org/wiki/Millimeter_wave_scanner#Possib...
I like this response a lot and am going to adapt it to explain this to my radiation-paranoid family.
The concept of wavelength as the sole distinction between these types of radiation is probably abstract to most non-science-educated people. Can you (or anyone else) think of a good concrete real-world analogy of different types of X that vary only in Y and some X are harmless but those with Y are not? Maybe an analogy of throwing sand at someone vs. shooting a bullet?
The concept of wavelength as the sole distinction between these types of radiation is probably abstract to most non-science-educated people. Can you (or anyone else) think of a good concrete real-world analogy of different types of X that vary only in Y and some X are harmless but those with Y are not? Maybe an analogy of throwing sand at someone vs. shooting a bullet?
The sand/bullet one is probably apt, if indirect. The issue is that different "kicks" get absorbed in different ways by the stuff which makes up your cells. One gets absorbed by the chemical bonds and tears them apart; one gets absorbed by the molecule as a whole.
I think maybe the best way to give the idea is to contrast a car crash with a bullet at the same energy. According to Wikipedia, a really strong rifle cartridge (in this case, the .220 Swift) fires its bullet with at most 2.4 kJ of kinetic energy, which is about the energy of me moving at 15 mph. So you can imagine me, getting shot, flying backward at ~10 mph. But also there's the exact same energy and momentum transfer as is in me falling asleep and veering into a tree while driving at 10 mph. So why do I think that the 10mph crash is survivable as long as I don't get thrown from the vehicle, while the bullet would likely be fatal?
The difference is that the seat belt distributes the force over most of my upper torso, whereas the rifle distributes all of its kick in a particular place. Similarly, the "smaller" photons distribute all of their kick on particular atoms, while the "bigger" photons tend to distribute their kick on the protein as a whole. One "rips the stuff apart", the other causes it to bump into its surroundings more.
I think maybe the best way to give the idea is to contrast a car crash with a bullet at the same energy. According to Wikipedia, a really strong rifle cartridge (in this case, the .220 Swift) fires its bullet with at most 2.4 kJ of kinetic energy, which is about the energy of me moving at 15 mph. So you can imagine me, getting shot, flying backward at ~10 mph. But also there's the exact same energy and momentum transfer as is in me falling asleep and veering into a tree while driving at 10 mph. So why do I think that the 10mph crash is survivable as long as I don't get thrown from the vehicle, while the bullet would likely be fatal?
The difference is that the seat belt distributes the force over most of my upper torso, whereas the rifle distributes all of its kick in a particular place. Similarly, the "smaller" photons distribute all of their kick on particular atoms, while the "bigger" photons tend to distribute their kick on the protein as a whole. One "rips the stuff apart", the other causes it to bump into its surroundings more.
Thanks.
What's your take on the possibility of damage suffered from exposure to RF radiation? There are reports from credible institutions (/u/jamoes mentions one above) that RFR, despite causing "only heating", may have detrimental impacts.
When I see lists of studies like this [1], it's hard to know what to think. Are most of these weak studies or unsettled science?
I know this is a really broad question; I'm obviously not asking for comments on specific studies listed those tables. I'm curious about comments on the seeming contradiction between the observation that at a theoretical level RF radiation at moderate intensity is thought to be known to be provably harmless, and the large number of reports of observed non-trivial(?) effects.
[1] http://www.bioinitiative.org/rf-color-charts/
What's your take on the possibility of damage suffered from exposure to RF radiation? There are reports from credible institutions (/u/jamoes mentions one above) that RFR, despite causing "only heating", may have detrimental impacts.
When I see lists of studies like this [1], it's hard to know what to think. Are most of these weak studies or unsettled science?
I know this is a really broad question; I'm obviously not asking for comments on specific studies listed those tables. I'm curious about comments on the seeming contradiction between the observation that at a theoretical level RF radiation at moderate intensity is thought to be known to be provably harmless, and the large number of reports of observed non-trivial(?) effects.
[1] http://www.bioinitiative.org/rf-color-charts/
That's really hard for me to answer, because while I can address the physics side pretty well the physiology side is not really my forte. More importantly, you have to have someone who knows the studies holistically rather than piecemeal, because of the numbers.
What I mean is -- and I'm not necessarily accusing bioinitiative.org; I'm just stating that it's something we have to watch out for -- it's possible for a lot of reports from credible institutions that have good, correct studies warning about X, even if X is totally harmless.
One of the easiest ways for this to happen is the simple fact that at least one in twenty journal results should be wrong, because that's how 95% confidence intervals work. If a thousand 95% studies are done on a safe thing then you should ideally have 50 studies which can't make that conclusion.
Let me speak about a case which is related which I do know a little about; the Interphone study. This was a massive international case-control study on the effect of mobile phone radiation (also microwaves) on various forms of brain cancer. You can see one of the full articles reporting the data here:
http://ije.oxfordjournals.org/content/39/3/675.long
In this case, bioinitiative.org released a press release stating "Today’s release of the final results of the ten-year long World Health Organization INTERPHONE Study confirms previous reports showing what many experts have warned – that regular use of a cell phone by adults can significantly increase the risk of glioma by 40% with 1640 hours or more of use (this is about one-half hour per day over ten years). Tumors were more likely to occur on the side of the head most used for calling."
I will state that that press release -- not necessarily the whole bioinitiative.org project; I don't know enough to say that, but that press release in particular -- is cherry-picking the data significantly. Lots of bloggers picked up this headline too, but I don't think they read the scientific study that they were blogging about (as a rule).
If you actually look at that study you'll see -- to take table 2 as my example -- that there is a table of 50 results presented with 95% confidence intervals. Of those 50 results, a shocking twenty of them result a statistically-siginificant observed preventative effect of cell phone radiation on meningioma and glioma while only one of them (the glioma case that they cite) showed a statistically observed damaging effect. The authors' actual conclusion was much more meek, "Overall, no increase in risk of glioma or meningioma was observed with use of mobile phones. There were suggestions of an increased risk of glioma at the highest exposure levels, but biases and error prevent a causal interpretation. The possible effects of long-term heavy use of mobile phones require further investigation." (There may even be simple correlations which would cause cell-phone users to have less cancer -- maybe strong social bonds protect against cancer and cause cell phone use; or maybe people who use their brains more find the distraction of cell phones harder to resist and also have a higher turnover in brain cells, making it harder for cancer cells to find purchase, or something.)
As far as I know, that is the largest study that has ever been done on cancer, but there may be other "detrimental impacts" (as you call them) which are not cancer, of course. You would need to consult someone who has a holistic view of the info, not a physicist who happened to read that one study when it came out in 2010.
What I mean is -- and I'm not necessarily accusing bioinitiative.org; I'm just stating that it's something we have to watch out for -- it's possible for a lot of reports from credible institutions that have good, correct studies warning about X, even if X is totally harmless.
One of the easiest ways for this to happen is the simple fact that at least one in twenty journal results should be wrong, because that's how 95% confidence intervals work. If a thousand 95% studies are done on a safe thing then you should ideally have 50 studies which can't make that conclusion.
Let me speak about a case which is related which I do know a little about; the Interphone study. This was a massive international case-control study on the effect of mobile phone radiation (also microwaves) on various forms of brain cancer. You can see one of the full articles reporting the data here:
http://ije.oxfordjournals.org/content/39/3/675.long
In this case, bioinitiative.org released a press release stating "Today’s release of the final results of the ten-year long World Health Organization INTERPHONE Study confirms previous reports showing what many experts have warned – that regular use of a cell phone by adults can significantly increase the risk of glioma by 40% with 1640 hours or more of use (this is about one-half hour per day over ten years). Tumors were more likely to occur on the side of the head most used for calling."
I will state that that press release -- not necessarily the whole bioinitiative.org project; I don't know enough to say that, but that press release in particular -- is cherry-picking the data significantly. Lots of bloggers picked up this headline too, but I don't think they read the scientific study that they were blogging about (as a rule).
If you actually look at that study you'll see -- to take table 2 as my example -- that there is a table of 50 results presented with 95% confidence intervals. Of those 50 results, a shocking twenty of them result a statistically-siginificant observed preventative effect of cell phone radiation on meningioma and glioma while only one of them (the glioma case that they cite) showed a statistically observed damaging effect. The authors' actual conclusion was much more meek, "Overall, no increase in risk of glioma or meningioma was observed with use of mobile phones. There were suggestions of an increased risk of glioma at the highest exposure levels, but biases and error prevent a causal interpretation. The possible effects of long-term heavy use of mobile phones require further investigation." (There may even be simple correlations which would cause cell-phone users to have less cancer -- maybe strong social bonds protect against cancer and cause cell phone use; or maybe people who use their brains more find the distraction of cell phones harder to resist and also have a higher turnover in brain cells, making it harder for cancer cells to find purchase, or something.)
As far as I know, that is the largest study that has ever been done on cancer, but there may be other "detrimental impacts" (as you call them) which are not cancer, of course. You would need to consult someone who has a holistic view of the info, not a physicist who happened to read that one study when it came out in 2010.
Thanks. I very much appreciate your substantive response.
Ocean waves crashing against a retaining wall. It doesn't matter how many small waves come, it's only waves greater than a certain height that are dangerous.
Maybe you could relate it to temperature? A simple quantity, but intuitively safe at some magnitudes and dangerous at others.
PS: so in electromagnetic radiation, shorter wavelengths carry more energy, whereas in sound, longer wavelengths (bass) carry more energy. (Right?) I'm not physics-savvy enough why these effects are opposite; is there an explanation for this?
It's worth understanding that the light which you see is the result of many photons -- though it's usually estimated that maybe, if our rod/cone cells were a little more sensitive, they might have been able to perceive individuals. So actual energy/mass transfer comes from a lot of particles each offering their own individual kicks. So the overall intensity is not just (energy per kick) but really (number of kicks) * (energy per kick). The number of kicks counts.
Phonons, for sound, actually are quantized in the exact same way as for light -- just replacing the speed of light c with the speed of sound in the medium v. (Both arguments are based on analogies to a harmonic oscillator problem which every quantum mechanics course works out; basically any vibration in the bottom of a potential well X can be dealt with by approximating that potential well with a parabola, which leads to particles, we could call them X-ons, of one form or another. Quantum mechanics makes all particles act like waves but also makes all waves quantize into particles.)
So, long-story-short, the physics is the same, and long wavelength phonons also carry less energy per kick than shorter ones, just like photons. That's not the difference, and the E = h f equation is still the same. But for phonons it's more about numbers.
The biggest sound particles you can hear correspond to 20,000 Hz frequencies. The smallest light particles you can see correspond to 700 nm wavelengths or 10^15 Hz frequencies. So photons are more than 50 billion times more energetic than phonons, as a rule.
This changes a lot of features about them. For example, every degree of freedom in a system has some average energy due to just random energy-sharing, which is known colloquially as the "temperature" of the system. If you work out how many 20kHz phonons there are simply due to a room being at room temperature, it works out to about 300 million. Any detector which registers 20kHz phonons, including the hairs in your ear, have 300 million of those phonons in them just from random thermal excitation. On the other hand, the red light receptors in your eye have on average (300 million) / (50 billion) = 0.006 photons in them on average, meaning that if you look at a thousand of those photon-absorbers you'll see on average only six of them which are excited randomly just by thermal excitations. So we can, at room temperature, detect individual photons, where we can't detect even ten thousand phonons at once without it getting hopelessly buried in thermal noise. (But our eyes simply do not fire the neurons when a light-sensitive cell only sees one photon.)
Phonons, for sound, actually are quantized in the exact same way as for light -- just replacing the speed of light c with the speed of sound in the medium v. (Both arguments are based on analogies to a harmonic oscillator problem which every quantum mechanics course works out; basically any vibration in the bottom of a potential well X can be dealt with by approximating that potential well with a parabola, which leads to particles, we could call them X-ons, of one form or another. Quantum mechanics makes all particles act like waves but also makes all waves quantize into particles.)
So, long-story-short, the physics is the same, and long wavelength phonons also carry less energy per kick than shorter ones, just like photons. That's not the difference, and the E = h f equation is still the same. But for phonons it's more about numbers.
The biggest sound particles you can hear correspond to 20,000 Hz frequencies. The smallest light particles you can see correspond to 700 nm wavelengths or 10^15 Hz frequencies. So photons are more than 50 billion times more energetic than phonons, as a rule.
This changes a lot of features about them. For example, every degree of freedom in a system has some average energy due to just random energy-sharing, which is known colloquially as the "temperature" of the system. If you work out how many 20kHz phonons there are simply due to a room being at room temperature, it works out to about 300 million. Any detector which registers 20kHz phonons, including the hairs in your ear, have 300 million of those phonons in them just from random thermal excitation. On the other hand, the red light receptors in your eye have on average (300 million) / (50 billion) = 0.006 photons in them on average, meaning that if you look at a thousand of those photon-absorbers you'll see on average only six of them which are excited randomly just by thermal excitations. So we can, at room temperature, detect individual photons, where we can't detect even ten thousand phonons at once without it getting hopelessly buried in thermal noise. (But our eyes simply do not fire the neurons when a light-sensitive cell only sees one photon.)
"More energy" can mean two different things. In the case of sound, only one of those meanings--the amplitude of the wave--is relevant: soft sounds have lower amplitude and loud sounds have higher amplitude. The frequency of the wave, as jessaustin pointed out, is independent of how soft or loud it is, and for sound, there isn't any useful sense in which any frequency carries "more energy" than any other frequency, given that the amplitudes are the same.
With regard to light, however, there is a second possible meaning for "more energy": not a higher amplitude of the classical wave, but more energy contained in a single quantum of the light (i.e., a single photon). Light of higher frequency (toward the blue/ultraviolet end of the spectrum) has more energy per quantum; light of lower frequency (toward the red/infrared/microwave end of the spectrum) has less. This sense of "more energy" is still independent of wave amplitude: wave amplitude corresponds to number of photons (more precisely, the number of photons is proportional to the amplitude squared). So you can have faint light (few photons) of high frequency (more energy per photon); or you can have bright light (lots of photons) of low frequency (less energy per photon). The total energy contained in the light depends on both of these factors; but the total energy in the light is not the crucial factor involved (see below).
It turns out that, when you are looking at the possible effects of radiation on the body, the energy per photon is the most important factor, because that is what determines what kind of interactions the radiation can have with the molecules that make up your body. UV, X-rays, and gamma rays have enough energy per photon to break apart the chemical bonds that hold together things like proteins in your cells; that's what makes them potentially cancer-causing. Microwaves, OTOH, don't have enough energy per photon to break chemical bonds; all they can do is make the molecules, like proteins, vibrate more rapidly, which just means heating them up.
With regard to light, however, there is a second possible meaning for "more energy": not a higher amplitude of the classical wave, but more energy contained in a single quantum of the light (i.e., a single photon). Light of higher frequency (toward the blue/ultraviolet end of the spectrum) has more energy per quantum; light of lower frequency (toward the red/infrared/microwave end of the spectrum) has less. This sense of "more energy" is still independent of wave amplitude: wave amplitude corresponds to number of photons (more precisely, the number of photons is proportional to the amplitude squared). So you can have faint light (few photons) of high frequency (more energy per photon); or you can have bright light (lots of photons) of low frequency (less energy per photon). The total energy contained in the light depends on both of these factors; but the total energy in the light is not the crucial factor involved (see below).
It turns out that, when you are looking at the possible effects of radiation on the body, the energy per photon is the most important factor, because that is what determines what kind of interactions the radiation can have with the molecules that make up your body. UV, X-rays, and gamma rays have enough energy per photon to break apart the chemical bonds that hold together things like proteins in your cells; that's what makes them potentially cancer-causing. Microwaves, OTOH, don't have enough energy per photon to break chemical bonds; all they can do is make the molecules, like proteins, vibrate more rapidly, which just means heating them up.
Thanks.
Sound energy is unrelated to audio frequency. Intuitively, it's possible to have quiet, deep sounds and loud, high-pitched sounds.
I think you're right (audio frequency doesn't appear in the formulas I found for sound energy), but I don't think the analogy fully demonstrates why, since it's also possible to have bright or dim light of a particular color!
The issue about the energy of electromagnetic radiation depending on frequency is, if I understand correctly, a quantum issue.
https://en.wikipedia.org/wiki/Photoelectric_effect
That is, quantum theory explains why there is such a thing as nonionizing electromagnetic radiation.
The issue about the energy of electromagnetic radiation depending on frequency is, if I understand correctly, a quantum issue.
https://en.wikipedia.org/wiki/Photoelectric_effect
That is, quantum theory explains why there is such a thing as nonionizing electromagnetic radiation.
It's also possible to have faint blue light, and bright red light.
Sound energy is quantized too, but for audible frequencies, hf is small compared to kT, so quantum effects are swamped by thermal effects.
Sound energy is quantized too, but for audible frequencies, hf is small compared to kT, so quantum effects are swamped by thermal effects.
Millimeter wave scanners are of an entirely different kind of 'radiation' than backscatter X-rays in the same way 'red light' is of a different kind of radiation from 'alpha particles'. Yes, technically they are are the "radiation" of an emitted particle from an interaction. But they are of significantly, quantitatively, and oncogenically different kinds of 'radiation'.
Backscatter X-ray radiation is of very high intensity and almost certainly can cause damage to biological surface tissue. Millimeter wave uses non-ionizing radiation - it does not have the capability of causing what we generally refer to when we speak of biological damage by radiation. It might do something else - though this seems to be debatable, and largely hypothetical, it is simply incapable of the damage that a backscatter X-ray machine could realistically cause.
Here's the letter authored by significant scientists written to the White House in regards to their thoughts on the backscatter machines [1].
[1] http://www.ucsf.edu/sites/default/files/legacy_files/concern...
Backscatter X-ray radiation is of very high intensity and almost certainly can cause damage to biological surface tissue. Millimeter wave uses non-ionizing radiation - it does not have the capability of causing what we generally refer to when we speak of biological damage by radiation. It might do something else - though this seems to be debatable, and largely hypothetical, it is simply incapable of the damage that a backscatter X-ray machine could realistically cause.
Here's the letter authored by significant scientists written to the White House in regards to their thoughts on the backscatter machines [1].
[1] http://www.ucsf.edu/sites/default/files/legacy_files/concern...
Note that this view of "cumulative ratiation" is a myth, and a costly one. A recent note on this: http://atomicinsightscom.c.presscdn.com/wp-content/uploads/C...
(there's not only a treshold, there may also be some hormesis, i.e. a slight decline in cancer rate for small doses)
(there's not only a treshold, there may also be some hormesis, i.e. a slight decline in cancer rate for small doses)
This one page paper with one figure and six data points from an author nobody knows in a journal nobody has heard of is right. The generally accepted models of radiation dose must be thrown out the window.
No, there is ionizing radiation and nonionizing radiation. X-rays are ionizing radiation with photon energies higher than visible light. THz RF radiation is nonionizing and has photon energies that are less than that of visible light.
If you're worried about this, you shouldn't fly at all. The amount of radiation your body is exposed to during the flight is several orders of magnitude larger than the amount it's exposed to during the security screening. Not only that, the radiation you're exposed to during the flight is higher energy (cosmic rays are the major component) and can do more damage to your body than the microwaves used in the security scanners.
A light bulb subjects the body to radiation.
A light-bulb's light also doesn't penetrate solid objects. It's clearly a different type of radiation than standard light.
Our bodies aren't subject to millimeter wave radiation in nature, so they're not really evolved to defend against it.
I'm not against further studies of millimeter wave radiation and its effects on humans, I just don't want to be a guinea pig in those studies.
Our bodies aren't subject to millimeter wave radiation in nature, so they're not really evolved to defend against it.
I'm not against further studies of millimeter wave radiation and its effects on humans, I just don't want to be a guinea pig in those studies.
Umm...glass is a "solid object" the last time I checked. And no, it's electromagnetic radiation, period -- it's a different wavelength (just like blue is a different wavelength than red).
Look for the reply from the physicist for greater detail as to why you're completely confused, though. I opted out of the Backscatter X-Ray machines due to what seemed like poor science; the MM wave devices may violate privacy, but that's their worst offense.
Look for the reply from the physicist for greater detail as to why you're completely confused, though. I opted out of the Backscatter X-Ray machines due to what seemed like poor science; the MM wave devices may violate privacy, but that's their worst offense.
To be fair, Jamie's is probably thinking of the human body. However, even in that case, you can see that light goes through the human body by holding a flashlight against your palm and seeing the glow on the back side of your hand.
That's not how evolution works...
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Sigh. Using bullshit to argue against bullshit just leaves the whole world shittier.
Sorry, yes, different models with different techniques - but the result is largely the same (and I would guess the weaknesses as well).
Aren't the machines in use today using the same technology? Instead of showing the full image, they are applying pattern matching and only showing suspect regions to the operators. Supposedly to protect privacy...
Backscatter machines (the big blue boxes) were removed. Millimeter wave machines (the clear plastic cylinder) are still in place.
From the FAQ:
> Q. Isn’t it bad to publish details of possible attacks?
> We have omitted a small number of sensitive details from our attacks in order to avoid providing recipes that would allow an attacker to reliably defeat the screening process without having access to a machine for testing.
> Q. Isn’t it bad to publish details of possible attacks?
> We have omitted a small number of sensitive details from our attacks in order to avoid providing recipes that would allow an attacker to reliably defeat the screening process without having access to a machine for testing.
And the USENIX page: https://www.usenix.org/conference/usenixsecurity14/technical...
"To a degree that surprised us, our attacks benefited from testing on the device itself. Our first attempts at implementing a new attack strategy were often visible to the scanner, and reliable concealment was made possible only by iteration and refinement.
[...]
The effectiveness of such a strategy depends critically on the difficulty of obtaining access to the machine. In addition to the device we purchased, at least one other Secure 1000 was available for sale on eBay for months after we obtained ours. We do not know whether it sold, or to whom."