0:00:00 > 0:00:02Hello and welcome to Bang Goes The Theory.
0:00:02 > 0:00:05Nowadays we live in a life full of gadgets.
0:00:05 > 0:00:08Mobile phones, tablet computers and microwave ovens.
0:00:08 > 0:00:12We have all heard horror stories over the years about using mobiles
0:00:12 > 0:00:16being bad for us and scrambling our brains.
0:00:16 > 0:00:20Or how a wireless device next to your child's cot might put them in danger.
0:00:20 > 0:00:24Tonight we look at all the science behind wireless technology.
0:00:24 > 0:00:28Later, Howard Stableford updates a story
0:00:28 > 0:00:31he first reported 20 years ago
0:00:31 > 0:00:34about the dangers of wireless signals.
0:00:34 > 0:00:37This little sticker has oscillating quartz crystals.
0:00:37 > 0:00:41Put it on your tablet and it protects you from radiation.
0:00:41 > 0:00:42And this one is interesting.
0:00:42 > 0:00:45This mesh is silver-coated
0:00:45 > 0:00:49and protects you from radio waves wherever you are.
0:00:49 > 0:00:53Liz discovers that despite being widely seen as a health risk
0:00:53 > 0:00:57mobile phone signals can be used to save lives.
0:00:57 > 0:01:02What are the advantages of this as opposed to your regular X-ray scans?
0:01:02 > 0:01:06X-ray is not very good at detecting tumours in young women.
0:01:08 > 0:01:11And I am in the US to reveal how we might eventually be able
0:01:11 > 0:01:13to transmit not only information
0:01:13 > 0:01:16but also power to our gadgets.
0:01:16 > 0:01:18So this is the infrared equivalent of a solar panel.
0:01:18 > 0:01:20Correct.
0:01:20 > 0:01:24We can take that voltage and apply it to power our transistor radio.
0:01:24 > 0:01:26Nice.
0:01:26 > 0:01:29That is quite astonishing.
0:01:29 > 0:01:32It is hard to imagine life without wireless signals.
0:01:32 > 0:01:36But it is easy to forget that for our mobile phones, computers,
0:01:36 > 0:01:38televisions and wireless gadgets to work
0:01:38 > 0:01:42we all have to live in a soup of invisible radiation.
0:01:46 > 0:01:51Because seeing is believing, we have assembled these little gizmos.
0:01:51 > 0:01:55- Dallas, grab yourself that. - Thank you very much indeed.
0:01:55 > 0:01:58That detects mobile phone signals.
0:01:58 > 0:02:01The stronger the signal the more lights light up.
0:02:01 > 0:02:07It is a strong signal. Liz, you take this. Same deal as Dallas.
0:02:07 > 0:02:10Why is mine not as big as Dallas's?
0:02:10 > 0:02:12Yours is designed to pick up wi-fi signals.
0:02:12 > 0:02:16- The stronger the signal, again, the more lights you get.- Got you.
0:02:16 > 0:02:21And mine picks up invisible radio waves.
0:02:21 > 0:02:25We will walk around the space and with a bit of camera magic
0:02:25 > 0:02:28we can reveal the invisible world of wireless waves.
0:02:28 > 0:02:30- Ready?- Go.
0:02:33 > 0:02:37This estate looks pretty quiet but the air waves are teeming.
0:02:37 > 0:02:40It is just that up until now you could not see them.
0:02:40 > 0:02:43But with our cameras you can. Look at this.
0:02:44 > 0:02:46These are radio waves in the red.
0:02:46 > 0:02:49This maps out the strength of one particular station.
0:02:49 > 0:02:54Mobile phones, shown in green. Fairly consistent signals.
0:02:54 > 0:02:58And look at the new kid on the block, wi-fi, coloured purple.
0:03:00 > 0:03:03Everyone's got a wi-fi network these days.
0:03:03 > 0:03:06There is a peak as I walk past each house.
0:03:06 > 0:03:10But, for all the brilliant things wireless does for us,
0:03:10 > 0:03:14many of the waves connecting us and our gadgets are microwaves.
0:03:14 > 0:03:16That has caused lots of people to worry
0:03:16 > 0:03:19about how safe these devices really are.
0:03:19 > 0:03:23Which is not surprising. Let me show you why.
0:03:23 > 0:03:27Watch this. I will give my wi-fi box a bit of a job to do
0:03:27 > 0:03:31by streaming a high-definition video to this computer.
0:03:31 > 0:03:34The wireless router is sending the video to my computer
0:03:34 > 0:03:37using tiny microwave signals.
0:03:38 > 0:03:43Then I am going to warm up my cup of tea.
0:03:49 > 0:03:51Houston, we have a problem.
0:03:51 > 0:03:54All microwave ovens leak a few microwaves
0:03:54 > 0:03:56and if that is close to your computer
0:03:56 > 0:04:00they can interfere with the microwaves from the wi-fi.
0:04:00 > 0:04:04Interference that can cause a video screen to stop.
0:04:04 > 0:04:10But switch off the microwave and we are cleared for take-off again.
0:04:10 > 0:04:13You can see the computer picking up loads of information
0:04:13 > 0:04:16from the microwave signals coming out of the wi-fi unit.
0:04:16 > 0:04:19But when the signals from the microwave oven
0:04:19 > 0:04:21start interfering with it, it drops off a cliff and then -
0:04:21 > 0:04:24ping - my cup of tea is finished,
0:04:24 > 0:04:27right back up, it is working up a treat.
0:04:27 > 0:04:30The reason is because those microwaves
0:04:30 > 0:04:34and the microwaves from the wi-fi box are exactly the same.
0:04:34 > 0:04:37Radio waves, microwaves, light waves,
0:04:37 > 0:04:40all types of electromagnetic radiation.
0:04:40 > 0:04:43But depending on their frequency, where they come in the spectrum,
0:04:43 > 0:04:45they behave very differently.
0:04:45 > 0:04:49Light waves show the world around us. Microwaves boil water.
0:04:53 > 0:04:55So how come if there is all this
0:04:55 > 0:04:58microwave wireless energy buzzing around
0:04:58 > 0:04:59none of us are cooking?
0:04:59 > 0:05:03Well, what is going on in there is about 4,000 times more powerful
0:05:03 > 0:05:07than what you have in your wi-fi router.
0:05:07 > 0:05:09Because they're doing different jobs.
0:05:09 > 0:05:12This is trying to produce a manifest physical change
0:05:12 > 0:05:14on the food and drink inside
0:05:14 > 0:05:18but the wi-fi router is just trying to send a signal.
0:05:18 > 0:05:21The difference between waving at somebody and walking over
0:05:21 > 0:05:23and punching them in the face.
0:05:24 > 0:05:28But despite the reassurance the idea of being bathed in microwaves
0:05:28 > 0:05:30has never been popular,
0:05:30 > 0:05:33as Howard Stableford first reported 26 years ago.
0:05:35 > 0:05:39Overhead power lines, radio transmitters and radars,
0:05:39 > 0:05:41even everyday visual display units,
0:05:41 > 0:05:44they're all sources of a form of radiation.
0:05:46 > 0:05:50Since 1986, when we recorded that item for Tomorrow's World,
0:05:50 > 0:05:54the apparent dangers of gadgets using microwave signals
0:05:54 > 0:05:55have been widely debated.
0:05:55 > 0:06:00A quick search produces dozens of websites listing terrible symptoms.
0:06:00 > 0:06:04All caused, people say, by phones and wi-fi.
0:06:04 > 0:06:08In fact the fear of microwaves is now so strong
0:06:08 > 0:06:11that you can buy all sorts of protective devices.
0:06:13 > 0:06:17This is interesting. A spray, called electro-smog protection.
0:06:20 > 0:06:24Just squirt it on like that. It does not smell very good though.
0:06:24 > 0:06:28This is a little sticker of oscillating quartz crystals.
0:06:28 > 0:06:30NASA technology.
0:06:30 > 0:06:33You put that on your tablet and it protects you from radiation.
0:06:33 > 0:06:36Similar idea with this band.
0:06:36 > 0:06:39And this one is interesting,
0:06:39 > 0:06:44this silver-coated mesh protects you from radio waves wherever you are.
0:06:46 > 0:06:48None of these gadgets convincingly explain
0:06:48 > 0:06:51how they are supposed to protect us, but they do sell.
0:06:51 > 0:06:54So plenty of people must have genuine concerns
0:06:54 > 0:06:58about how safe wireless is.
0:06:58 > 0:07:02Back in 1986 evidence for ill health was purely anecdotal
0:07:02 > 0:07:05but of course things have moved on.
0:07:05 > 0:07:09Now we have the results of carefully controlled experiments
0:07:09 > 0:07:14that can explain at least some of the illnesses associated with microwaves.
0:07:14 > 0:07:17We took a group of 60 individuals and brought them into our laboratory
0:07:17 > 0:07:22and asked them to wear a specially designed headset with a device
0:07:22 > 0:07:26that looks very much like a mobile phone strapped to the side.
0:07:26 > 0:07:29We exposed them to two things.
0:07:29 > 0:07:33Either a real digital mobile phone signal or a sham condition.
0:07:33 > 0:07:36So the equipment would still beep, and heat up with the red lights
0:07:36 > 0:07:40coming on it, but it did not emit anything out of the aerial.
0:07:40 > 0:07:45And importantly we did not tell the participants which was which.
0:07:45 > 0:07:47The results showed conclusively
0:07:47 > 0:07:49that, although they did experience symptoms
0:07:49 > 0:07:52in the experiment, they were getting headaches,
0:07:52 > 0:07:55they were just as likely to get them in the sham condition
0:07:55 > 0:07:57as in the real condition.
0:07:57 > 0:08:01So if these symptoms aren't due to electromagnetic fields,
0:08:01 > 0:08:03what are they due to?
0:08:03 > 0:08:06- Because these people really are ill, aren't they?- Absolutely.
0:08:06 > 0:08:09So we think people who think mobile phone signals
0:08:09 > 0:08:13or other electromagnetic fields are harmful,
0:08:13 > 0:08:16when they believe they've been exposed to them, it's that belief
0:08:16 > 0:08:19that can trigger their symptoms, rather than the actual exposure.
0:08:21 > 0:08:24You'd think that James's study and others like it
0:08:24 > 0:08:28would reassure people who worry about the apparent dangers of microwaves.
0:08:29 > 0:08:30But they don't.
0:08:32 > 0:08:37This is Barnoldswick, a peaceful market town in Lancashire.
0:08:37 > 0:08:42Back in April 2009, the local council here decided it would be a good idea
0:08:42 > 0:08:45to put up a wi-fi network in the town centre,
0:08:45 > 0:08:48the first town in the North of England to do so,
0:08:48 > 0:08:53allowing local businesses and people fast, free access to the internet
0:08:53 > 0:08:57and bringing Barnoldswick speeding into the 21st century.
0:08:57 > 0:09:01The plan would have made Barnoldswick among the first towns in Britain
0:09:01 > 0:09:06to have such an extensive public wi-fi network.
0:09:06 > 0:09:08But people weren't happy.
0:09:08 > 0:09:10Existing broadband speeds here
0:09:10 > 0:09:14are pretty useless, and we wanted to give people the opportunity
0:09:14 > 0:09:18to access much better connection to the internet.
0:09:18 > 0:09:22Unfortunately, we had a lot of objections from people
0:09:22 > 0:09:25who were concerned about the health risks of wi-fi.
0:09:26 > 0:09:31Even after 26 years of research, there is still no medical way
0:09:31 > 0:09:34to explain how microwaves could cause cancer.
0:09:34 > 0:09:38But just a few studies have reported links,
0:09:38 > 0:09:42so there are people who won't rule out the possibility
0:09:42 > 0:09:44of new medical explanations.
0:09:44 > 0:09:49And despite a complete lack of proven cancer cases, the debate continues.
0:09:49 > 0:09:54Now, I looked at similar issues to these in 1986, and then,
0:09:54 > 0:09:56I pretty much would have guaranteed that by now,
0:09:56 > 0:09:5926 years later, we would have definitive answers.
0:09:59 > 0:10:00Why haven't we?
0:10:00 > 0:10:02For a very long-term disease,
0:10:02 > 0:10:06one that maybe takes ten years or more to develop,
0:10:06 > 0:10:10obviously you can't know till that period has elapsed.
0:10:10 > 0:10:15We have data at the moment up to 10 to 15 years, but beyond that,
0:10:15 > 0:10:16we can't know,
0:10:16 > 0:10:19because people haven't been using phones for long enough.
0:10:19 > 0:10:21There's a very important study called Cosmos
0:10:21 > 0:10:23that the UK's taking part in,
0:10:23 > 0:10:25which is trying to do a much better assessment
0:10:25 > 0:10:27than was done in previous studies.
0:10:27 > 0:10:30It's doing that by following people forward in time,
0:10:30 > 0:10:32but we can't know the answer until the study's run its course.
0:10:34 > 0:10:36LIZ@ While we'll have to wait a while
0:10:36 > 0:10:39for proof that wireless is completely safe,
0:10:39 > 0:10:41the technology is marching onwards,
0:10:41 > 0:10:43turning up in some very unexpected places.
0:10:44 > 0:10:48Microwaves, radio waves, wi-fi - they're all things that make us think
0:10:48 > 0:10:51about the technology we use every day,
0:10:51 > 0:10:53everything from mobile phones to the internet.
0:10:53 > 0:10:57But they're also connected to landmines and cancer,
0:10:57 > 0:11:00and I'm going to meet a man who's going to explain why.
0:11:01 > 0:11:04Landmines injure or kill over 4,000 people a year
0:11:04 > 0:11:08in over 70 countries but, despite heroic efforts,
0:11:08 > 0:11:11finding mines in active and former war zones
0:11:11 > 0:11:14has become much more difficult in recent years
0:11:14 > 0:11:17as munitions technology has advanced.
0:11:18 > 0:11:21Ten years ago, the military came to Professor Ian Craddock,
0:11:21 > 0:11:24an electrical engineer at Bristol University.
0:11:24 > 0:11:27They asked him for help with this problem.
0:11:27 > 0:11:29Ian, when you were working with the Ministry of Defence,
0:11:29 > 0:11:32- what was the challenge? - They were interested in the problem
0:11:32 > 0:11:36of detecting small plastic anti-personnel landmines
0:11:36 > 0:11:38buried in the ground.
0:11:38 > 0:11:40How did you go about solving that problem?
0:11:40 > 0:11:43You can't find these landmines with a metal detector,
0:11:43 > 0:11:46because there's almost no metal content in a small mine nowadays.
0:11:46 > 0:11:49So we have to choose part of the electromagnetic spectrum
0:11:49 > 0:11:51which is able to penetrate into the ground.
0:11:51 > 0:11:54It's a bit like the visible light spectrum
0:11:54 > 0:11:56we see in this stained-glass window.
0:11:56 > 0:11:58Some panes of glass are transparent to blue light.
0:11:58 > 0:12:02Some panes of glass are transparent to red light, but it turns out
0:12:02 > 0:12:03that the soil is reasonably transparent
0:12:03 > 0:12:06to the microwave part of the spectrum
0:12:06 > 0:12:10that we're more familiar with with the uses of wireless technology.
0:12:12 > 0:12:15Microwaves can travel through the ground in the same way
0:12:15 > 0:12:17that light can pass through glass.
0:12:17 > 0:12:19But look at this.
0:12:19 > 0:12:22Even though glass and water are both transparent,
0:12:22 > 0:12:23we can see the glass beads
0:12:23 > 0:12:27in this water, and that's because light moves slower
0:12:27 > 0:12:29in glass than it does in water.
0:12:29 > 0:12:31Because of this contrast,
0:12:31 > 0:12:33we can tell the difference between the two.
0:12:37 > 0:12:39It's the same with the plastic landmines.
0:12:39 > 0:12:42Microwaves travel through and bounce off plastic differently
0:12:42 > 0:12:44than they do in earth,
0:12:44 > 0:12:48and so microwave receivers can see the buried mine.
0:12:49 > 0:12:51This discovery helped Ian
0:12:51 > 0:12:55to design a new type of microwave-based landmine detector,
0:12:55 > 0:12:57but it also took his career
0:12:57 > 0:13:00down a different, but equally life-saving path.
0:13:00 > 0:13:03This is a system for detecting breast cancer.
0:13:03 > 0:13:08This is the imaging head, so we've got a cup containing antennas,
0:13:08 > 0:13:11- similar to the antennas you'd find in your mobile phone.- OK.
0:13:11 > 0:13:13This is an early prototype, easier to see here.
0:13:13 > 0:13:16So the woman will lie with her breast inside the cup,
0:13:16 > 0:13:19and then reflections generated from tumours
0:13:19 > 0:13:21come back into the ray of antennas.
0:13:21 > 0:13:23So basically looking at a difference
0:13:23 > 0:13:25in the properties of normal breast tissue and tumour tissue?
0:13:25 > 0:13:29Yeah. And we use software to process those signals
0:13:29 > 0:13:32and get a 3-D picture of the interior of the woman's breast.
0:13:32 > 0:13:37- So that red mass there...- That was a tumour inside this woman's breast.
0:13:37 > 0:13:39What are the advantages of using this
0:13:39 > 0:13:42as opposed to your regular scans that you get using X-rays?
0:13:42 > 0:13:46An X-ray is not very good at detecting tumours in young women.
0:13:46 > 0:13:51So why is it that microwaves show up that contrast better than X-rays?
0:13:51 > 0:13:54There's more contrast between the tissues at those frequencies.
0:13:54 > 0:13:58The contrast between different materials is not the same
0:13:58 > 0:14:02at one end of the electromagnetic spectrum as it is at the other.
0:14:02 > 0:14:04So while X-rays are great for looking at bones
0:14:04 > 0:14:07hidden under skin, microwaves are better
0:14:07 > 0:14:10for spotting the difference between tumours and normal breast tissue.
0:14:10 > 0:14:14And, as one in every five women diagnosed with breast cancer
0:14:14 > 0:14:15is under 50,
0:14:15 > 0:14:19Ian's device could help save thousands more lives.
0:14:19 > 0:14:23How close are we to being able to use this on a mass scale?
0:14:23 > 0:14:27This is certainly many years away from large-scale deployment,
0:14:27 > 0:14:31but it has already been used on cancer patients in Bristol.
0:14:31 > 0:14:34So we're surrounded by all this incredible wireless technology.
0:14:34 > 0:14:36It's safe.
0:14:36 > 0:14:40But the one thing we haven't got sorted yet is wireless power.
0:14:40 > 0:14:42You still have to plug something in.
0:14:42 > 0:14:44- Are we ever going to get that sorted?- Maybe.
0:14:47 > 0:14:50You can see the appeal. Wireless has given us
0:14:50 > 0:14:54countless devices that are free from cables supplying their information.
0:14:54 > 0:14:57And yet we still need plugs and wires to power them.
0:14:57 > 0:15:00If we could find a way to do that wirelessly too,
0:15:00 > 0:15:04we'd never need sockets, power leads or batteries ever again.
0:15:04 > 0:15:09Everything would simply work. Like these bulbs.
0:15:09 > 0:15:13These bulbs really do have absolutely no wires connected to them.
0:15:16 > 0:15:19So why don't we have a system like this at home
0:15:19 > 0:15:20in all our living rooms?
0:15:20 > 0:15:24Well, that's because it's also extremely dangerous.
0:15:25 > 0:15:28The only reason that this works as well as it does
0:15:28 > 0:15:31is because I've got a metal plate above my head.
0:15:31 > 0:15:34It's set at a few hundred thousand volts.
0:15:34 > 0:15:37And when you get massive voltages like that,
0:15:37 > 0:15:41they have quite a large field of influence, large enough in this case
0:15:41 > 0:15:44to excite the atoms within these tubes sufficiently
0:15:44 > 0:15:47that they cause the whole tube to glow.
0:15:47 > 0:15:50And in order to produce that huge electric field,
0:15:50 > 0:15:54I've had to connect my plate via that copper pipe
0:15:54 > 0:15:58to a strange-looking contraption over here.
0:15:58 > 0:16:00This is a Tesla coil.
0:16:00 > 0:16:03It's our version of something that was invented over 100 years ago
0:16:03 > 0:16:08by the visionary but slightly mad genius, Nikola Tesla.
0:16:08 > 0:16:12These things are capable of generating hundreds of thousands,
0:16:12 > 0:16:13if not millions of volts.
0:16:13 > 0:16:15And Tesla built huge versions,
0:16:15 > 0:16:18with the intention of transmitting power wirelessly
0:16:18 > 0:16:20over vast distances.
0:16:22 > 0:16:27The trouble is that the voltages are so huge that Tesla coils,
0:16:27 > 0:16:30even small ones like this, can also produce lightning,
0:16:30 > 0:16:32which is why traditionally
0:16:32 > 0:16:36we've kept our electricity safely trapped in insulated wires.
0:16:36 > 0:16:41Wires are incredibly good at transporting electrical power.
0:16:41 > 0:16:44There's precious little power loss between where it's generated
0:16:44 > 0:16:46and where you're plugging in the device you're using.
0:16:46 > 0:16:48But we're inherently lazy,
0:16:48 > 0:16:52and we'd really rather not go to the trouble
0:16:52 > 0:16:54of having to plug everything in.
0:16:54 > 0:16:58So is there a way of having useful wireless power
0:16:58 > 0:17:01without having to resort to massive, fatal voltages?
0:17:01 > 0:17:02Yes, there is.
0:17:06 > 0:17:09Electric toothbrushes and, more recently,
0:17:09 > 0:17:12mobile phone charging mats
0:17:12 > 0:17:16certainly manage a little bit of wireless power transfer
0:17:16 > 0:17:18without the massive voltages.
0:17:18 > 0:17:21How do they do it? They do it with magnetism. It works like this.
0:17:21 > 0:17:23What I've got here is a coil.
0:17:23 > 0:17:26If you put an electric current through a coil,
0:17:26 > 0:17:28it becomes an electromagnet.
0:17:33 > 0:17:37Switch the current off, and it's no longer an electromagnet.
0:17:41 > 0:17:43Now, if you were to put
0:17:43 > 0:17:47another coil of wire within that field of magnetism,
0:17:47 > 0:17:52you can actually turn that magnetism back into electricity.
0:17:52 > 0:17:54And, strangely enough,
0:17:54 > 0:17:59you do that by varying that magnetic field as much as possible,
0:17:59 > 0:18:02which you can do by simply switching it on and off.
0:18:09 > 0:18:13Pleased as I may be with my little piece of wireless power transfer,
0:18:13 > 0:18:17it is still a bit weedy and hardly life-changing.
0:18:17 > 0:18:18Unlike this.
0:18:21 > 0:18:25Now, we're just using a lamp lightbulb at the moment.
0:18:25 > 0:18:31But you could genuinely run a telly a couple of feet from a wall
0:18:31 > 0:18:34using something very similar. So what's different?
0:18:38 > 0:18:41See, whereas I was switching that on and off
0:18:41 > 0:18:43maybe once or twice a second at best,
0:18:43 > 0:18:48the electronics here switch on and off a million times a second.
0:18:48 > 0:18:52And the faster you switch it, the greater its area of influence.
0:18:52 > 0:18:55But even with all that super-fast switching,
0:18:55 > 0:18:59it's still limited to, well, a couple of feet.
0:18:59 > 0:19:01That's because magnetic fields
0:19:01 > 0:19:03drop off quite dramatically with distance.
0:19:05 > 0:19:11So, how would you go about getting wireless power transfer over huge distances,
0:19:11 > 0:19:13something really worthwhile?
0:19:13 > 0:19:16For inspiration, you could look to the sky,
0:19:16 > 0:19:19because here on Earth, we get almost all our power
0:19:19 > 0:19:24from a massive, glowing orb about 93 million miles away.
0:19:24 > 0:19:28And there are no wires between the Earth and the sun.
0:19:28 > 0:19:30We get all our power wirelessly.
0:19:30 > 0:19:35So maybe the answer to long-distance wireless power is light.
0:19:35 > 0:19:37I'm going to leave you with that thought for a while,
0:19:37 > 0:19:40but we will return to it at the end of the programme.
0:19:40 > 0:19:43Dallas, I think you'll find the solution is impressively space-age.
0:19:43 > 0:19:47- It had better go further than a metre.- It will.
0:19:47 > 0:19:51OK, it's time for your weekly dose of my favourite wireless gadget,
0:19:51 > 0:19:52Dr Yan Wong.
0:19:52 > 0:19:54Mobile phones are relatively new,
0:19:54 > 0:19:59but would you believe the first wireless telephone was invented
0:19:59 > 0:20:01more than 130 years ago?
0:20:01 > 0:20:07The sound was carried on nothing more than a beam of sunlight.
0:20:07 > 0:20:08Can you figure out how they did it?
0:20:08 > 0:20:11The answer to that, of course, is on the website.
0:20:11 > 0:20:12And whilst you're there,
0:20:12 > 0:20:14you can also get yourself one of these posters.
0:20:14 > 0:20:17It features many of the things from this series and shows
0:20:17 > 0:20:19how batteries, power cables,
0:20:19 > 0:20:22microwaves and hearing aids are all connected.
0:20:22 > 0:20:24You can get your free copy by ringing:
0:20:27 > 0:20:28Or by following the links
0:20:28 > 0:20:31from bbc.co.uk/bang to the Open University.
0:20:31 > 0:20:33Also, check us out live.
0:20:33 > 0:20:36We're still on tour with the Bang roadshow.
0:20:36 > 0:20:39Next stops, Sheffield and Poole. We'd love to see you.
0:20:39 > 0:20:42For details, go to:
0:20:47 > 0:20:50Right. Back to my quest for wireless power,
0:20:50 > 0:20:53and the dream of consigning cables and batteries to history.
0:20:53 > 0:20:54Sound like a pipe dream?
0:20:54 > 0:21:00Well, remember, we get plenty of energy from the sun every day,
0:21:00 > 0:21:01with no wires at all.
0:21:01 > 0:21:06We routinely turn light into electricity using solar panels.
0:21:06 > 0:21:09But solar panels don't just work off sunshine,
0:21:09 > 0:21:12they work pretty well off artificial light too.
0:21:12 > 0:21:13The problem is,
0:21:13 > 0:21:17the further I move my torch away from my solar panel,
0:21:17 > 0:21:21the more spread out the beams become and the less power I can collect.
0:21:21 > 0:21:24For this to work over a long distance,
0:21:24 > 0:21:27you need a light source that barely spreads out at all,
0:21:27 > 0:21:29something like a laser.
0:21:30 > 0:21:31With a laser beam,
0:21:31 > 0:21:35the intensity of its power remains almost exactly the same
0:21:35 > 0:21:38however far along the beam you go,
0:21:38 > 0:21:40just like electrical power in a cable.
0:21:40 > 0:21:42With all the power of the laser
0:21:42 > 0:21:44staying in such a concentrated beam,
0:21:44 > 0:21:47the intensity of the light can be extremely dangerous.
0:21:49 > 0:21:52But I've heard about a system that gets around this problem,
0:21:52 > 0:21:55making it safe to transfer power from one place to another
0:21:55 > 0:21:59with no wires in between. I've come all the way
0:21:59 > 0:22:01to the United States to see it.
0:22:01 > 0:22:05Laser expert Robert Windsor has been setting it up to show me.
0:22:05 > 0:22:08At the moment, that's just a normal red laser pointer
0:22:08 > 0:22:11he's using to line the system up.
0:22:11 > 0:22:13The working laser is far more powerful.
0:22:13 > 0:22:17This particular fibre feed here delivers
0:22:17 > 0:22:22approximately 20,000 times the power of a typical laser pointer.
0:22:22 > 0:22:26'And it gets worse than that. It's an invisible laser beam.
0:22:26 > 0:22:29'It uses infrared light that we can't see,
0:22:29 > 0:22:33'but which carries a huge amount of energy.'
0:22:33 > 0:22:35Look, straight away!
0:22:35 > 0:22:39- That's astonishing. That's like something out of James Bond.- Yeah.
0:22:41 > 0:22:47Right, I'm utterly convinced that you've got a very powerful laser.
0:22:47 > 0:22:49'As impressive as this display is,
0:22:49 > 0:22:53'the dream of wireless power is looking like a choice
0:22:53 > 0:22:56'between being electrocuted by the Tesla coil or being burnt alive.
0:22:56 > 0:22:59'But Robert's system has a safety feature.'
0:22:59 > 0:23:02That's the part where the optics come in
0:23:02 > 0:23:08to expand the beam into a safer, larger diameter where,
0:23:08 > 0:23:12if you get into the beam, you won't get harmed by that.
0:23:12 > 0:23:17'With a special card, I can make the invisible beam visible.'
0:23:17 > 0:23:23- It's really warm.- It can surprise you at times.- Oh, my life.
0:23:23 > 0:23:27- So, can we go and see where it's hitting at the far end?- Sure.
0:23:27 > 0:23:31The receiving end is a quarter of a kilometre away,
0:23:31 > 0:23:33on the other side of the campus.
0:23:33 > 0:23:36But the laser beam is as powerful here as it was when it left.
0:23:36 > 0:23:43- And this is what collects that fat, infrared beam?- Yes.
0:23:43 > 0:23:46- So it's the infrared equivalent of a solar panel.- Correct.
0:23:46 > 0:23:52And then we can take that voltage and apply it to power up an LED.
0:23:52 > 0:23:57- Or, we've also got a transistor radio here.- Oh, nice!
0:23:57 > 0:24:02And how efficiently does that then convert the power in the beam
0:24:02 > 0:24:03back to electricity?
0:24:03 > 0:24:10We're probably really converting maybe 10-15% of it into useful energy
0:24:10 > 0:24:15- to drive the LED or the radio. - I love how it goes in and out.
0:24:15 > 0:24:17'And although my hand can block the beam,
0:24:17 > 0:24:20'this does seem to be a remarkably practical system
0:24:20 > 0:24:24'for long-distance wireless power. It even works in the rain.'
0:24:24 > 0:24:28A little bit of rain really doesn't hurt it all that much.
0:24:28 > 0:24:32In fact, sometimes I've had trouble noticing any difference at all.
0:24:32 > 0:24:36But is it genuinely, like, throughout the whole range,
0:24:36 > 0:24:40wherever it goes, perfectly OK to not blind anybody?
0:24:40 > 0:24:42With this wavelength and this kind of energy density,
0:24:42 > 0:24:45you could put your face into it. It's totally safe.
0:24:45 > 0:24:50Getting a normal laser beam in your eye can blind you instantly.
0:24:50 > 0:24:55Never, ever look down one. But Robert is a safety specialist.
0:24:55 > 0:24:58Everything else I know about lasers says this wouldn't be a good idea.
0:24:58 > 0:25:01Under his guidance, I'm about to demonstrate
0:25:01 > 0:25:06what makes his system different from almost every other in the world.
0:25:08 > 0:25:11Oh, you can really feel the warmth there.
0:25:11 > 0:25:14'All the power of that laser, safely spread out
0:25:14 > 0:25:17'and at a wavelength that won't even damage my eyes. I'm convinced.
0:25:17 > 0:25:21'It is possible to beam power to our gadgets
0:25:21 > 0:25:25'without any wires, safely and over enormous differences.
0:25:25 > 0:25:29'In fact, huge distances are just what it lends itself to.'
0:25:29 > 0:25:32In fact, what really got this whole thing rolling
0:25:32 > 0:25:36was the NASA Centennial Challenge, which was a space elevator project,
0:25:36 > 0:25:38if you will, beaming power
0:25:38 > 0:25:42to a vehicle that could climb a tether all the way into space.
0:25:42 > 0:25:46Not only could we beam power up to space, but also back down.
0:25:46 > 0:25:50Some groups are looking at putting lasers like these onto satellites
0:25:50 > 0:25:54to beam power from their efficient solar panels
0:25:54 > 0:25:57to anywhere on Earth, through the atmosphere and at any time,
0:25:57 > 0:25:58day or night.
0:25:58 > 0:26:00Now, it may never be
0:26:00 > 0:26:04the cheapest or most efficient electricity available.
0:26:04 > 0:26:05But imagine.
0:26:05 > 0:26:07You're in the middle of the Antarctic,
0:26:07 > 0:26:10a thousand miles from the nearest plug socket.
0:26:10 > 0:26:13I think you'd be very grateful for any power you can lay your hands on.
0:26:13 > 0:26:16That's a really interesting film.
0:26:16 > 0:26:19So obviously, wireless power transfer works in principle,
0:26:19 > 0:26:23but how long before we can realistically have it in a domestic setting
0:26:23 > 0:26:26so that you don't have to plug your telly into the wall?
0:26:26 > 0:26:27I think it's going to be a long time
0:26:27 > 0:26:30before any of us have houses big enough
0:26:30 > 0:26:32to justify being powered with a laser beam.
0:26:32 > 0:26:35Plus, if you did have one of those infrared lasers,
0:26:35 > 0:26:37the kids would want to play in it all the time,
0:26:37 > 0:26:39it's so lovely and warm,
0:26:39 > 0:26:42thereby cutting off the telly when you most want to watch it.
0:26:42 > 0:26:44So "don't hold your breath" is the message.
0:26:44 > 0:26:46Don't unplug your TV just yet.
0:26:46 > 0:26:50Next time on Bang, we'll be looking at your energy levels.
0:26:50 > 0:26:53What is it that makes them rise and fall through the day?
0:26:53 > 0:26:56What happens to you if you don't drink enough water?
0:26:56 > 0:26:58I just want to neck that.
0:26:58 > 0:27:02And Jem finds out if it's possible to boost your energy levels
0:27:02 > 0:27:04just by drinking beetroot juice.
0:27:06 > 0:27:09- See you then.- Bye!
0:27:34 > 0:27:39Subtitles by Red Bee Media Ltd