Extremely Fast: The Science of Speed

You might have heard that the UK’s first ever 5G network has just been launched. With growing coverage across major UK cities, it promises faster speeds than ever. But what actually makes it different from previous networks? Izzie Clarke and Katie Haylor were joined in the studio by Paul Beastall, member of the UK5G Advisory Board, but what is 5G?

Paul - 5G simply is the fifth generation of mobile phone technology.

Izzie - Oh, and that's what the G stands for. I've actually never really thought about it. What is it and how is it different from 4G?

Paul - It's the latest evolution. It brings a number of technologies together so it uses higher radio frequencies that allow us to get more information through a given radio channel. It brings computing further out towards the edge of the network which means we can reduce latency so we can do services with far less delay. And it's also designed to cope with very, very high densities of simple terminals to allow us to connect everything in the long-term.

Izzie - We're seeing it rolled out in UK cities, is it anywhere else?

Paul - The UK's one of the leading countries, but it's certainly not the first. There's some deployments in the US, there's quite a lot of activity in Asia. From a technology perspective, most of the radio innovation is coming out of China, Japan, and Korea, but some of the applications are being developed in the UK, so we are still innovating.

Izzie - What's it capable of?

Paul - If we want to think about numbers, so we’re thinking about bit rates, targets of up to 10 gigabits per second which means you can download a DVD in 10/15 seconds, something like that in the best conditions possible, so not everywhere. For me, more interestingly, it means the latency, the delay across a network can drop down to only a millisecond, so a thousandth of a second, which means that when humans are interacting with networks we can have information overlaid on the top of what we’re doing. So you could do things like remotely control robots in real time doing very delicate and challenging tasks or use augmented reality to give our eyes more information than we can see ourselves.

Izzie - How is 5G able to hold so much more information than 4G?

Paul - There's two reasons. The first one is by going up in radiofrequency to higher parts of the radio spectrum there's more bandwidth available, so we can use more bandwidth for each radio channel which means we can just put more data through that. The other thing is it includes a technology called massive MIMO which allows us to actually send beams targeted at individuals users. At the moment, if you're on a radio base station on 4G, normally what you find is that capacity is shared among everybody else who's in the same street as you, with 5G we can literally point beams of radio energy at individual users.

Izzie - Paul, how is this all connected?

Paul - Effectively what we have, we have a radio in a handset or a terminal that’s in an embedded device - something like a car, and that makes a radio link to what we call a base station and all versions of mobile technology use this same architecture with base stations. And then from there it actually goes over optical fibre or fixed network connections back to what we call the core network which manages security and billing, and just make sure that everything works. Things like international roaming gets managed that way as well. So unlike Wi-Fi, which is just a short connection and then straight out to the internet, there's a whole network behind cellular technologies as well.

Izzie - Oh, wow. Are there any disadvantages to 5G compared to 4G?

Paul - Yes. At the moment it's expensive, it's new technology, it will take time to evolve. We see that with all new technologies so it's not going to be that we get all the benefit immediately. The millimetre wave frequency, these very high frequencies we're using have some challenges that they don't go through human bodies, they don't go through walls so actually, you need to be quite close to the base stations to get the service that you need. So we’re talking about smaller coverage areas, much greater performance.

Izzie - Do you think you could see those base stations incorporated into everyday life? Like could we have one, say, on a traffic light because we know that they're so useful when we have them everywhere?

Paul - Yeah, absolutely. And I think that's the change, so we’re going to go from network where we have 20,000 base stations per operator in the UK to potentially a million. 5G will enable some of the autonomous driving communication so I think street furniture, traffic lights, street lights are going to be really really important.

Izzie - Do you think this will ever take over 4G? Is this the end of 4G, essentially?

Paul - Not for a very long time. My iPhone does 2G, 3G, 4G. 2G's still not turned off here, it is in the US. So 4G will end eventually, probably, but not before 2030 at the earliest.

May the 29th marked an important Centenary for the world of physics: on that day in 1919, Cambridge Astronomer, Arthur Eddington, led teams to two continents to take what are now some of the most famous photographs we have. The results sent the scientific world into turmoil. Newton’s laws of gravity, that had stood unshaken for hundreds of years, were overturned by a young German scientist called Albert Einstein. To hear how it happened, Izzie Clarke headed over to the Institute of Astronomy at the University of Cambridge, to see space scientist Carolin Crawford.

Carolin - The dominant law of gravity was, of course, Newton's laws of gravity - which he had devised, and which proved a very accurate description of the way objects moved on the earth, and how the planets move round the sun. It was only during the middle part of the 19th century that it was clear that there was one thing it didn't quite account for, and that was the way that Mercury's orbit moved round the sun. But Einstein was the first one that could account for everything that Newton could account for - that we saw in space and on Earth - but could also justify what was happening to Mercury, due to an extra curvature of space-time in the proximity of the sun.

Izzie - This idea of space-time was at the heart of Einstein's theory: that space and time can be considered as one entity. I know, it's quite a lot to get your head around, but bear with me. Say you need to pop to the shops. You could say that they're 10 minutes away - or equally a few kilometres away. You can describe that journey in distance and time, because you know how fast you walk. There's a similar thing with space-time: that both space and time are interchangeable because you know the speed of light, and the speed of light is the same everywhere. And what Einstein then said that is so different from Newton is that this space-time could be distorted by massive objects like our sun - that they bend the shape of space, which creates that key difference in Einstein's theory of gravity.

Carolin - Light likes to travel in a straight line. But if you had the light from a distant star, a light ray, and it just grazed the surface of the sun - because the sun is the nearest large mass we have around - it would just deflect that light a little bit and cause a tiny shift in the apparent position of the stars, but it was so small it wasn't practically observable. The difference was that Einstein made a prediction that when you take into account the curvature of space you actually double the amount of that deflection, which brings it into the realms of observability; and it also provides a very nice discrimination between what Newton says and what Einstein says, if you could measure this deflection.

Izzie - But how can you measure the deflection of light from a distant object if your own giant fireball, i.e. our sun, is in the way? It would be impossible to distinguish the light from the two sources. The idea was proposed that pictures of distant galaxies could be taken during an eclipse, where the Moon blocks the light from our sun.

Carolin - So it wasn't a new idea to make this measurement, but the exciting thing was there was a particularly good eclipse coming up on 29th May 1919. It was good because it was of long duration, about six minutes or so, which gives you plenty of time to take your images. And also, quite unusually, the sun would be right in front of a very bright nearby star cluster - it's called the Hyadas, is in the constellation of Taurus - which meant that during the eclipse the sun would lie in a region surrounded by fairly bright stars, which would enable the observations. So Arthur Eddington, who was a director of the observatories here at Cambridge at the time, he was one of the few people who fully understood the theory to study Einstein's ideas. And it was Arthur Eddington and also particularly Frank Dyson, who was the Astronomer Royal at the time, who realised that this was a particularly momentous eclipse for doing this. What they decided to do was to make two expeditions. There was one that was led by Andrew Crommelin from the Royal Greenwich Observatory which took equipment to Sobral in northern Brazil, and they would catch the start of the eclipse. And then the path would move right across the Atlantic Ocean and on the other side you'd have Sir Arthur Eddington and his small team who would do the same observations on an island off the coast of West Africa. They're carrying out the same experiment in both locations, and the ideal thing about having two locations, of course, is that you're never quite sure of the weather; and indeed, both expeditions had problems. In Principe, off the west coast of Africa, Eddington had terrible weather; and so they took plenty of images, but in most of them there’s too much cloud in the way. And in Sobral, in Brazil, they had problems with the equipment - there was vibrations, which just ended up blurring some of the images. And in fact the really important data from Brazil were from a sort of backup telescope they'd just taken as a spare. But the true and precise measurements don't happen until they come back to the UK, and then the results are announced in November in 1919 at a very special occasion at the Royal Society in London.

Izzie - And what did they find?

Carolin - They found that their results vindicated Einstein's predictions of what should happen under his theory of gravity, rather than Newton’s.

Izzie - And how important was that finding, and what did that do for the field of physics?

Carolin - Well, it has revolutionised physics. I mean, at the time it was hugely important because very few people had really taken notice of Einstein's theories, and this idea of the whole curvature of light is quite a conceptual leap. And, to be quite honest, for a lot of scientists - and we have this in notes and letters - there is a resistance to having to use a more complicated theory. You know, if Newton's laws were sort of good enough, why not use those? But the point is, once this announcement is made, Einstein's relativity is proven as the better description of what happens on earth and in space - and at that point Einstein becomes the celebrity genius.

Izzie - And so Einstein's theory of general relativity was accepted: that what we perceive as the force of gravity in fact arises from that all-important curvature of space and time.

Carolin - Relativity is part of our general understanding of physics, so it's crucial to how we use physics. Now it may not make much difference here on earth, because Newton's laws are good enough. Where it becomes important is in more extreme situations - and so the closest thing to earth that people might run into everyday is of course your GPS satellites. If you didn't take into account the relativistic corrections for the fact that they're travelling in a reduced gravity field - and also faster compared to the surface of the earth - they would start to give you inaccurate results. Within a couple of minutes they'd be 10 km out per day. That's an immediate result that people might be able to relate to. I will say though, it's incredibly important for astronomers, because relativity gives the only good description of what happens where you have very large masses - and in astronomy, of course, you're involving the largest masses possible.

A lot of dangerous animals have speed on their side and there’s not a moment to lose when it comes to catching prey or defending your patch. And what better way to do so than producing some fast acting venom or poison to survive in the animal kingdom. Steven Allain from the University of Kent and member of the British Herpetological Society joined Katie Haylor in the studio.

Steven - Okay. A herpetologist is somebody who studies reptiles and amphibians. The word is Greek in origin. The root word is herpetós and essentially it means to creep.

Katie -  Okay. So we're talking reptiles and amphibians?

Steven - Reptiles and amphibians; snakes, frogs, lizards, all that sort of stuff.

Katie - Before we get really into this subject, can you just explain the difference between a poison and a venom?

Steven - Certainly. This is a question I get asked a lot and the main difference is that a poison needs to be ingested or it can also be taken through the skin, where a venom has a delivery mechanism such as stinger, a barb, or fangs.

Katie - Talking of poisons and venoms then, what are some of the most fast acting - this is a show about extreme speed - fast acting, most poisonous, venomous animals?

Steven - Some of the fastest are animals such as the box jellyfish which, its venom can act within 2 to 5 minutes of being stung, although not always, that leads to death by cardiovascular collapse. And then you also have dart frogs with a very strong toxin that also acts within a handful of minutes as well.

Katie - So what's going on then in the bodies of the prey in both of those cases, but also in the bodies of the ones inflicting the trouble?

Steven - In the body of the prey or the person or the animal that has been envenomated or poisoned, the main change is that their nervous system is shutting down. The neurons aren't firing, or they're overfiring which then causes issues with the cardiovascular system which shuts down your lungs and your heart, and then you unfortunately die. In the predators or the envenomaters, they are producing toxins in specialised cells or glands. And in the case of the dart frogs, they sequester their poisons through their diet, and so when you take them out of that natural setting - keep them as pets - they're no longer as toxic because they no longer have the specialised beetles or ants where they get these toxins from.

Katie - And we mentioned the box jellyfish. I imagine that probably lives in the sea, right? Where are we talking?

Steven - It does, yes. It lives in the seas around Australia and although they are extremely dangerous there are very few deaths from box jellyfish stings a) because people avoid them, and b) because there are relatively quick emergency response action plans in place to deal with them if they do occur.

Katie - One animal, I guess, may be stereotyped, or people think of when they think of poison is snakes. So how fast are snakes then at envenomating people?

Steven - When it comes to snake venom it can act very fast. Black Mamba venom, it takes about half an hour to act and then after that you're pretty much done for, unless you seek immediate medical attention. Again, it's a neurotoxin so it acts on the nervous system, although other snakes have venoms that can breakdown blood or create clots which have different effects but are more long ranging and also take longer to undertake than shutting down you nerves.

Katie - We're talking about extreme speed in this show and I guess there's the speed at which the venom or the poison gets to work, but there's also that speed at which you're actually causing that damage, right, so how quickly do snakes spring into action?

Steven - A lot of research has been done on this and it doesn't matter whether you're a venomous snake or a nonvenomous snake, all snakes seem to strike around the same speed. And to just put that into perspective, rattlesnakes have been clocked at going 2.9 metres per second which is 6 1/2 mph. It doesn't sound like much, it's just faster than a brisk walk, but in an enclosed space that's pretty fast. It means that in a strike zone, a snake can strike you in about 75 milliseconds, a human blinks in 200 milliseconds, so they can strike you almost 3 times in the time it takes you to blink.

Katie - So why do snakes need a) so much venom, and b) to be able to get it in someone so fast? What's the point?

Steven - You have to think that a lot of species feed on fast moving prey, particularly quite small prey and the amount of venom and the strike speed has all evolved to be able to immobilise that prey immediately, or extremely quickly so it doesn't wander off and die hundreds of metres away from where the snake is. So it can just get its item of food and disappear off in the undergrowth away from the risk of predation or being exposed to the elements.

Katie - This is pretty extreme stuff we're talking about, what are the chances of survival then? For instance, for human beings, what do you do if you're in this very unfortunate situation?

Steven - If you do suffer a snakebite and you are envenomated by a venomous snake it is imperative that you seek medical attention immediately, and it's also important that you identify which species of snake that envenomated you. There are antivenoms which can counteract the venom of a number of species and these are found particularly in areas such as India where you have a number of species that are highly venomous. But in other countries there's only one or two species where you could come across a snake that may cause damage and so you have more specific antivenom to that one species.

Katie - How do you actually make an antivenom, because you need to understand the venom, the way the chemistry and biology is working? Does that mean you have to extract some out of the incredibly dangerous animal?

Steven - It does, yes. You have to take a lot of safety precautions when it comes to handling venomous animals obviously. And depending on whether you’re working with a snake or a spider there are different procedures to extract that venom. And in terms of creating the antivenom, traditionally sheep or horses are used. Because they are quite large, you can inject quite a lot of venom in them and it doesn't really have any negative effects apart from shortening the lifespan, unfortunately, and then you extract the antibody that's produced from the blood and that goes into the anti-venom.

Katie - And finally, how far away are we from a 'catch all' antivenom then? Is it possible to make something that you could give to someone who had got any particular venom or, indeed, poison?

Steven - At the moment that is impossible, no. Although the World Health Organisation is pumping money into that problem as we speak. They've just announced global snakebite is a neglected tropical disease and they're trying to fund a universal antivenom for anybody around the world by any snake species to be able to treat that by using HIV antibody technology. At the moment is still in its infancy, but it does show some promise for the future.

Katie - So we should be watching this space then?

Steven - We should definitely be watching this space, yes.

We’ve covered humans, animals and cars but when it comes to extreme speed, there’s one thing that takes the crown; light. Light is the fastest thing in our universe but how do we know that? And what happens when we get to such a high speed? With Izzie Clarke and Katie Haylor is Matt Bothwell from Cambridge University’s Institute of Astronomy. Just how fast is the speed of light?

Matt -  Very fast is the answer. The number is 299,792,458 metres per second.

Katie - You're going to have to put that into context for me.

Matt - Yes, of course. That's a number that's so big it doesn't make any sense, right. It's so fast you can get to the moon in about one second and you can get to the sun in about eight minutes even though that's 150 million miles away.

Katie - Right. Well whilst I wrap my head around that, how do we know that the speed of light is the number you've just quoted?

Matt - Right. So there's been lots of attempts to measure the speed of light over history. Galileo tried to do it by shining lanterns from hillsides and timing it but as we know now, obviously, the speed of light is far too fast for that to be effective. The first person to have a decent stab at measuring the speed of light was a Danish astronomer called Roemer. He was observing the moon Io, that's a moon of Jupiter, and we can see Io orbiting Jupiter and when it goes behind Jupiter that's an eclipse. What he noticed was that when the solar system is configured that the earth is moving towards Jupiter, the eclipses seem to happen more frequently than when we were moving away from Jupiter and that can only happen if light has a finite speed and we were catching up with the signals, if you like, when we were travelling towards Jupiter.

Katie - So crucially, the distance that the light was having to travel was changing depending on where the earth was?

Matt - Exactly. And it was taking either more time or less time depending on which way round.

Katie - How well did he do in terms of getting the answer?

Matt - For a historical experiment he got pretty close to the actual answer, yeah.

Katie - And crucially, the speed of light is constant, right?

Matt - That's right. It's actually quite a bizarre thing to get your head around. It doesn't behave the way we expect speeds to. If you imagine, if you could throw a tennis ball at 50 mph for example, if you were to stand on a moving train going 50 miles an hour and throw the same tennis ball, the speed of the tennis ball would be 50+50, a 100 miles an hour because the speeds add together. The speed of light doesn't behave that way. The speed of light is about 300,000 kilometres per second. If you were to stand on a train and shine a torch out in front of you, that light is still going at 300,000 kilometres a second. It’s not the speed of light plus the speed of the train. The speed of light is always the same no matter how you measure it.

Katie - So are we getting into the realms of relative motion versus what light does which is something different?

Matt - Right, exactly, yes. In order for the speed of light to be constant in every reference frame, space and time themselves need to distort to keep this so it's so. So basically this is the time dilation and length contraction that people might have heard of.

Katie - Oh, my gosh. By reference frame, do you just mean from any point in time, space, the universe?

Matt - Exactly, yeah. If I'm sitting at my bedroom and I measure the speed of light, I'll get the value it says in the textbook. If I'm shooting off in a rocket to the stars at some phenomenal speed and I measure the speed of light, I’ll get the same results.

Katie - So you talk about time dilation, is this the idea that because the speed of light is constant, to get a certain distance time has to change to compensate? Is that kind of what we're talking about here?

Matt - Exactly. The way it works is that if an object is moving very very fast then an external observer will see time for that object as moving more slowly. So if you take a clock and then you fling it off at some phenomenal speed and then you watch the clock it will appear to be running slowly, which sounds very theoretical but that's an experiment we've actually done. We've taken atomic clocks and put them on jumbo jets flying around the world, and the clock that flies around the world ends up slower than the clock that was sitting on the ground.

Katie - Wow! So this isn't just my perception of time?

Matt - Yeah, it's not a perceived thing. Time really is going slower.

Katie - Apart from light obviously, which travels at the speed of light, can anything else travel that fast?

Matt - Yeah. There are a few things that travel at this speed and so we call it the speed of light - it's actually a lot more general than that, it’s just the maximum speed of the universe. And anything that is massless, any particle that is massless, will travel at this speed. The most famous ones are photons right. They are particles of light, they have zero mass and so they travel at the speed of light. But there are other particles like gluons, they are little particles that glue protons together, they are also what we call massless particles so they travel at the speed of light. The force of gravity travels at the speed of light. Yes, so it's not just limited to light itself.

Izzie - Things that are massless travel at the speed of light so why is that mass relationship so important?

Matt - Anything that has mass in the universe like a person, or a star, or a ball, or anything takes energy to move it. If you want to move a person it going to take energy to give them a shove. So anything with mass takes more and more energy the faster you want to go. And then to take anything with mass and make them travel at the speed of light would take an infinite amount of energy, but anything that has zero mass travels at the speed of light automatically.

Izzie - Ah, I see.

Katie - Back here on earth, are there any applications for understanding the speed of light that we might use every day?

Matt - There are definitely applications. We used the speed of light to define the length of a metre. In the past, metres were defined in various different ways including the size of the earth and they had a natural physical object which was a metre. Nowadays, we use the speed of light to define a metre so that number that I gave before the speed of light is exact, there is no uncertainty because that's how we define our metre.

We have to deal with the speed of light in various ways on earth. Often it's an obstacle to workaround; for example, when you're designing computer chips the speed of light is the limit to how fast signals can move around and they have to design them accordingly. And even in fields as far off as finance for example, the speed of light is important. So with high-frequency trading selling stocks and shares at fantastic numbers of times per second, price information can only get sent out from places like London and New York at the speed of light, it can't go any faster. And so companies that do this high-frequency trading will want to get as close as possible to the centre so that the speed of light can reach them as soon as possible and shave off some crucial milliseconds.

Katie - Ah, so geographically as close as possible. Does milliseconds really make a difference, milliseconds?

Matt - They do, yeah. You wouldn't think it but yeah, with supercomputers running algorithms on the stock market milliseconds is where it counts.