WEBVTT - How do airport scanners work? 0:00:00.520 --> 0:00:03.600 Welcome to brain Stuff from how stuff works dot com 0:00:03.600 --> 0:00:15.240 where smart Happens. Him Marshall Brain with today's question, how 0:00:15.240 --> 0:00:19.279 do the new full body scanners at airports work? And 0:00:19.360 --> 0:00:22.320 this really is an interesting question because there's two parts 0:00:22.360 --> 0:00:26.319 to it. There's the actual technology of the scanners, but 0:00:26.360 --> 0:00:29.720 there's also the huge uproar they're causing right now, So 0:00:29.760 --> 0:00:32.480 we can look at both aspects of that and see 0:00:32.560 --> 0:00:35.960 how they're converging right now. The thing you notice if 0:00:35.960 --> 0:00:38.760 you've been watching the news is that there's a huge 0:00:39.000 --> 0:00:42.600 uproar around these new full body scanners that are being 0:00:42.640 --> 0:00:46.560 deployed at airports around the United States right now. There 0:00:46.600 --> 0:00:49.600 are people loudly claiming that the t s A is 0:00:49.720 --> 0:00:53.680 handcuffing them to chairs for refusing to be scanned, for example, 0:00:54.240 --> 0:00:56.960 and the t s A responding that it never happened. 0:00:57.320 --> 0:01:01.520 There are videos showing little toddlers dreaming during pat downs. 0:01:01.880 --> 0:01:06.640 There are calls for congressional oversight, passenger boycotts, acts of 0:01:06.840 --> 0:01:11.279 private protest t s A abolishment. Even in New Jersey 0:01:11.400 --> 0:01:14.200 there's claiming that they're going to stop the t s A, 0:01:14.920 --> 0:01:17.319 and in Orlando they claim that they're going to replace 0:01:17.400 --> 0:01:20.680 the t s A with private contractors, so there really 0:01:20.760 --> 0:01:23.440 is a big debate going on right now. There are 0:01:23.440 --> 0:01:26.440 many reasons why people tend not to like these new 0:01:26.520 --> 0:01:30.280 full body scanning machines, but the two primary complaints are 0:01:30.319 --> 0:01:35.280 health concerns from X ray radiation and privacy concerns, both 0:01:35.360 --> 0:01:38.119 from being groped during pat downs if you opt out 0:01:38.120 --> 0:01:41.360 of the scan and from the possibility of scanned photos 0:01:41.400 --> 0:01:45.480 being distributed. Whether you love or hate the Transportation Safety 0:01:45.480 --> 0:01:49.240 Administration and its mission, the mission is clear. The t 0:01:49.480 --> 0:01:53.120 s a's goal is to keep passengers from carrying weapons 0:01:53.120 --> 0:01:56.760 and explosives onto airplanes. We can generally agree as a 0:01:56.880 --> 0:02:00.160 society that this is a worthwhile goal. No one us 0:02:00.160 --> 0:02:02.760 to see a terrorist wearing a suicide bomb blow up 0:02:02.760 --> 0:02:04.920 and the airplane and kill three people in the air. 0:02:05.520 --> 0:02:08.040 One obvious way to carry the weapons on is in 0:02:08.160 --> 0:02:11.680 luggage and handbags. The other way is to attach them 0:02:11.680 --> 0:02:13.920 to your body. The X ray machines that we use 0:02:14.040 --> 0:02:17.800 to scan luggage are generally considered to be safe and effective, 0:02:17.880 --> 0:02:20.400 so no one's really worrying about those. But when it 0:02:20.440 --> 0:02:23.720 comes to searching the bodies of passengers, the use of 0:02:23.760 --> 0:02:28.400 metal detectors and normal pat downs appears to have problems. First, 0:02:28.639 --> 0:02:32.480 metal detectors can't detect some explosives, which often don't contain 0:02:32.560 --> 0:02:35.480 much metal, and a normal pat down may not be 0:02:35.680 --> 0:02:41.280 very effective. Passengers wiggle and complain. Passengers are naturally reluctant 0:02:41.280 --> 0:02:45.520 to have their personal areas explored by a stranger's hands. Therefore, 0:02:45.560 --> 0:02:48.960 the person doing the pat down may not be very thorough. 0:02:49.720 --> 0:02:52.200 And if certain parts of the body, for example, the 0:02:52.240 --> 0:02:56.560 genital areas or certain types of people for example toddlers, 0:02:56.600 --> 0:03:01.239 are deemed inappropriate for padding, then those obvious places to 0:03:01.360 --> 0:03:05.760 hide weapons. What is an alternative to full body scanners? 0:03:06.040 --> 0:03:09.679 One alternative would be to have passengers enter a private 0:03:09.760 --> 0:03:13.440 booth in which he or she would remove all clothing 0:03:13.440 --> 0:03:16.240 and hand it to an agent. Then the clothing and 0:03:16.320 --> 0:03:20.400 the passengers naked body or photographs thereof would be examined. 0:03:20.720 --> 0:03:23.760 Then the passenger would redress and exit the screening area. 0:03:24.360 --> 0:03:28.600 This would be effective, but it has two problems. First, many, 0:03:28.760 --> 0:03:33.000 perhaps most, passengers would openly rebel, and second, it could 0:03:33.040 --> 0:03:36.480 really slow down the screening process, making it more expensive. 0:03:36.920 --> 0:03:40.560 There might also be problems with pornography and child pornography laws. 0:03:41.240 --> 0:03:44.520 Instead of making everyone get naked in a booth. The 0:03:44.680 --> 0:03:48.280 t s A has instead deployed two types of screening 0:03:48.320 --> 0:03:52.680 machines that let passengers skip the undressing part. The machine 0:03:52.800 --> 0:03:57.640 undresses you by either using X rays or millimeter radio waves. 0:03:58.120 --> 0:04:00.880 The backscatter X ray technique is the one getting the 0:04:00.880 --> 0:04:05.000 most publicity at the moment. In this machine, visualize a 0:04:05.240 --> 0:04:08.800 beam of low power X rays, similar to a laser 0:04:08.840 --> 0:04:12.640 beam in dimensions, scanning across your body left or right, 0:04:12.800 --> 0:04:16.600 top to bottom. The machine uses detectors to see how 0:04:16.600 --> 0:04:19.160 many of the X rays scatter off of each point 0:04:19.160 --> 0:04:23.680 of your body. Certain materials like clothing don't cause much 0:04:23.720 --> 0:04:28.159 scatter at all. Skin has a certain characteristic scattering effect, 0:04:28.480 --> 0:04:32.440 as do different metals and certain kinds of explosives. The 0:04:32.520 --> 0:04:36.320 machine paints an image of the back scattered results point 0:04:36.360 --> 0:04:39.080 by point, and an agent looking at that image can 0:04:39.160 --> 0:04:43.120 see things like metals, ceramics, and explosives attached to a 0:04:43.160 --> 0:04:46.880 passenger's body. The image that comes back is basically an 0:04:46.880 --> 0:04:49.800 image of a naked human body. It's a strip search 0:04:49.920 --> 0:04:54.360 without the stripping. It's fast and efficient. So what's the problem. 0:04:54.400 --> 0:04:57.680 There are three? Actually, First, many people don't like the 0:04:57.760 --> 0:05:01.279 idea of having photos of their nake bodies taken by 0:05:01.360 --> 0:05:04.839 any means. In addition, there are a number of stories 0:05:04.839 --> 0:05:08.480 of abuse e g. You get attractive women being more 0:05:08.560 --> 0:05:13.200 likely to be scanned or leaked images. Supposedly impossible, but 0:05:13.360 --> 0:05:16.599 obviously not since leaked images are on the Internet, and 0:05:16.680 --> 0:05:20.800 it doesn't help to have the kind of stuff happening. Second, 0:05:20.839 --> 0:05:25.640 because X rays involve ionizing radiation, many, perhaps most people 0:05:25.720 --> 0:05:28.160 have health concerns. All you have to do is look 0:05:28.200 --> 0:05:31.360 at the public reaction around any new nuclear power plant 0:05:31.880 --> 0:05:35.960 or the public acceptance of sunscreens to understand these concerns, 0:05:36.440 --> 0:05:39.000 even if the experts and the t s A say 0:05:39.080 --> 0:05:42.960 the machines are safe. The third problem is the perception 0:05:43.080 --> 0:05:45.800 that it's much ado about nothing, that the t s 0:05:45.839 --> 0:05:51.280 A represents security theater rather than actual security. This idea 0:05:51.400 --> 0:05:53.760 first took root because the t s A has not 0:05:53.920 --> 0:05:58.479 traditionally been very proactive. A terrorist had to bring explosives 0:05:58.480 --> 0:06:00.920 in the soles of his shoes before the t s 0:06:01.000 --> 0:06:04.680 A scan shoes. A terrorist had to bring innocent looking 0:06:04.720 --> 0:06:07.800 liquids to mix a bomb in the air before liquids 0:06:07.800 --> 0:06:12.080 were prohibited. Printer cartridges were not banned until explosives showed 0:06:12.120 --> 0:06:15.479 up in printer cartridges, and millions of people get onto 0:06:15.480 --> 0:06:18.920 subways every day without any screening at all, and that 0:06:18.960 --> 0:06:21.760 seems to work all right. In the case of the 0:06:21.839 --> 0:06:26.360 back scatter scanners, the t s A actually is being proactive. 0:06:26.720 --> 0:06:30.120 It is plugging a security hole before anyone exploits it. 0:06:30.520 --> 0:06:32.960 But in doing that, the t s A has met 0:06:33.040 --> 0:06:36.440 with significant resistance. And there's another problem that no one's 0:06:36.480 --> 0:06:40.560 really discussing right now. A passenger who is striped search 0:06:40.720 --> 0:06:45.080 still has a currently undetectable way to bring in explosives. 0:06:45.400 --> 0:06:49.440 The passenger could swallow plastic explosives wrapped in rubber or 0:06:49.480 --> 0:06:53.359 plastic along with a detonator. The human stomach can hold 0:06:53.440 --> 0:06:56.920 a couple liters of food and is fairly resilient. One 0:06:56.960 --> 0:06:59.920 person was known to swallow seventy eight forks and spoons 0:07:00.000 --> 0:07:03.240 before having to see the doctor. There's no easy way 0:07:03.360 --> 0:07:06.320 right now to detect this approach short of medical X 0:07:06.440 --> 0:07:10.600 rays or ultrasound. That leaves us with our current spectrum 0:07:10.600 --> 0:07:13.480 of choices. At one end of the spectrum, we could 0:07:13.560 --> 0:07:16.600 let passengers walk onto airplanes like we let them walk 0:07:16.640 --> 0:07:20.680 onto subway trains, zero security of any kind. At the 0:07:20.720 --> 0:07:24.440 other end of the spectrum, we could give naked passengers 0:07:24.480 --> 0:07:28.280 full body cat scans before every flight. Somewhere in the 0:07:28.320 --> 0:07:31.280 middle is a level of security that the majority of 0:07:31.360 --> 0:07:36.720 passengers will willingly accept. Apparently, full body X rays scanners 0:07:36.760 --> 0:07:40.320 maybe a little beyond that limit at this moment in history. 0:07:43.040 --> 0:07:45.440 For moral this and thousands of other topics. 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