Shorter Days and Binning Best Before Dates

Is the Earth spinning faster? And what impact could removing date labels from produce have on food waste?
05 August 2022
Presented by Chris Smith, Julia Ravey
Production by Julia Ravey.


Earth with a best before date


In the world of science news this week, major supermarkets in the UK are removing their best before dates after data reveals just how much they sway our decisions to chuck food away. Plus, we dive into some physics to understand what influences how fast the Earth spins and how this fluctuates, the virtual robotic surgery techniques which helped separate Siamese twins in Brazil, and how gestures can make video meetings less fatiguing and more engaging.

In this episode

Food market

00:55 - Retailers drop food best before dates

Best before dates could be misleading people into throwing away food prematurely.

Retailers drop food best before dates
Estelle Herszenhorn, WRAP

In the UK we throw away four and a half million tonnes of food every year. Part of this is because of “best before dates”, a well intentioned step to inform shoppers but one which, regrettably, fools consumers into thinking food’s unsafe when it isn’t. Now the supermarket Waitrose is joining the ranks of Marks & Spencer, the Co Op, and Tesco, to help combat this crisis, by doing away with these dates on some food items. Earlier in the year, Morrisons did the same and urged their customers to use a “sniff test” instead! Julia Ravey has been rifling through her fridge to find out what she might otherwise have thrown out…

Julia - So in my fridge at the minute, it's looking pretty barren. The fridge isn't at its full capacity, I need to do a shop actually, but I was just having a look to see what produce I have in the fridge and the labels that are on that produce. I have some apples in the fridge, which I buy loose. With these, I'd still be definitely eating them. I also have some of my favorite food ever- cherry tomatoes. And these say 'best before the 2nd of August'. I'd still eat them. And then I have some kale, which also says second of August. Now, kale, when it's over the best before date, it tastes a lot drier. And I don't know if that's a placebo effect of me seeing the date, but I normally like to eat kale before that best before date. And it's exactly this labeling that has been removed in Waitrose this week, and in other supermarkets as well across the UK. The removal of labels isn't just random. It's actually based on scientific data. And this was acquired by the company WRAP. I spoke to Estelle Herszenhorn, a special advisor at WRAP, who told me some of the really shocking statistics around how much food waste we have in the UK.

Estelle - The average family throws away around 700 pounds worth of food each year and wasting food feeds climate change. So it's something that's really important to focus on.

Julia - And what exactly are you looking at in order to help us reduce our food waste?

Estelle - There are three key things that can really help reduce household food waste. One, being able to buy more fruit and veg items loose. That's important so we can buy the amount that we need. The second area is around removing date labels. So, best before dates tend to be the date on fruit and veg, but there's no requirement to have those date labels on fruit and veg in the UK. And then the third action is around what we can do in our homes to get more of our fruit and veg stored in the right place so it stays fresher for longer.

Julia - How do food labels influence our decisions to throw them away?

Estelle - So we did a whole tranche of work last year, which involved a whole range of different scientific studies and analysis, and one really interesting part of it was around the way that we interact with fruit and veg when there's a date label on it and when there isn't. And in those tests, we saw some really staggering results. So, we showed people five different fruit and veg items that are quite often wasted in our homes. So we looked at apples, bananas, broccoli, cucumber, and potatoes. And as part of the study, we showed 1500 people images of each of those items at various different stages of deterioration. So if you imagine a really green under-ripe banana, then through to a super over-ripe black banana that you'd maybe use in a smoothie or the COVID popular banana bread. And then we showed people those same images, some with a date label on and some without. The really staggering results we found was that the date label being there was having a much bigger impact on people's choices. When we showed people an image of a yellow banana - so, perfect -when there was a date label on it around a third of people said that they would throw that item away. Whereas when there wasn't a date label, that same image, only 3% of people said they would throw the item away. And that was the same when we looked at all the different fruit and veg items that we tested. We also looked at trying to better understand what the scale of impact would be on reducing food waste. If we were to be able to get rid of those date labels. And what we've estimated is that around 50,000 tons, so that's 7 million shopping baskets worth of fruit and veg could be saved from becoming waste in our homes. If date labels were removed from fruit and veg.

Julia - So it seems that we are quite heavily influenced by those date labels. So if we were to remove them and we had food without that best before on, are there ways in our homes that we can keep fruit and vegetables fresh for longer?

Estelle - Absolutely potatoes and apples lasted months longer, two months longer, if you store them in the fridge compared within the fruit bowl or on the side. And broccoli, which is obviously a more perishable item, it's gonna go off quicker than apples and potatoes, that lasted two weeks longer. If it was stored in the fridge below five degrees, which is the magic number. So something we can all do to make our food stay fresher for longer is to put fruit and veg in our fridge.

The Earth see from space, with the Sun just beginning to emerge from behind it

06:38 - Why is Earth spinning faster?

Two days in the past two months have been 1.5 milliseconds faster than days in the past few decades

Why is Earth spinning faster?
Matt Bothwell, Institute of Astronomy, Cambridge University

Earlier this week, measurements made by the UK’s National Physical Laboratory showed that the Earth was spinning faster; one day in June and another in July were over a millisecond and a half shorter than measurements made during the preceding decades. This was widely reported as “Earth’s shortest day ever”. That’s not true though, is it, Matt Bothwell, Cambridge University’s Public Astronomer: the Earth used to spin much faster in the past and has been slowing down. These new readings just buck the trend of the last 50 years or so…

Matt - Right. Exactly. The earth is about four and a half billion years old. And so in the past, the earth was spinning a lot quicker than it is now. You wouldn't have to go back in time much more than a billion years or so to have days less than 20 hours long. So yes, it's the shortest day for the last couple of hundred years maybe.

Chris - And why hitherto is the Earth's rate of rotation been slowing down?

Matt - Well, it's something called tidal friction. So the moon's gravitational pull on the earth is a bit uneven because the earth is not a perfect sphere. So as earth spins around, the moon's pull causes this phenomena, which physicists call tidal friction, which tugs on the earth and gently acts as a break on its rotation.

Chris - Does that mean then that we are giving some of Earth's rotational energy to the moon?

Matt - Yes, exactly. Yes. The system is losing energy, and so the moon is actually having the same effect. This tidal friction causes the moon to move away from the earth. It's happening very slowly. It's about the same speed that your fingernails grow, but over very long periods, it would be notable.

Chris - And that has had the effect of slowing down rotation and therefore days have been lengthening over time.

Matt - Yes, exactly. So we have a 24 hour day now. In the past, around a billion years ago, our day was about 19 hours. I think go back another billion years. Our day would've been about 14 hours. So yes, the earth is getting slower and lazier with time as we all do, I guess.

Chris - Why then does it appear to have bucked the trend because the headline was the Earth's suddenly speeding up. So where would it get the energy to go from a slower speed to a faster speed again?

Matt - It turns out that the answer is really complicated and I think it's hard to narrow down one single explanation because often when we think of the earth spinning in space, we just think of like a blue marble or something just rotating away. But the earth has loads of complex internal structure. There's magma sloshing around the middle and there's water sloshing around on the top and all that can do funny things to the spin. So one potential explanation is that the melting of the polar ice caps is redistributing the weight away from the poles and towards the center and that might cause a slight increase. But there are lots of different things that can be causing this. So it's hard to narrow it down to one.

Chris - Is it a bit similar then to when one watches ice skating or ballet and you have a dancer or an ice skater doing a pirouette, one of the first things they do is they're turning in a big circle. They've got their arms and legs out all over the place, and then they pull them into the centre of their body and they'll speed up. That's because they're moving the mass instead of in a big circle, they're moving it through a much smaller one. So everything has to speed up. Could the earth be doing a similar sort of thing by redistributing the mass around itself? You're not suddenly finding new energy. It's just that you redistribute the spin and that speeds things up.

Matt - Yeah, exactly. That's one really good way to put it. I had a physics professor in undergrad who used to do this memorable thing a bit like an ice skater, but he did it on a spinning office chair with weights and he would spin himself around with the weight at arm's length, and then bring them into his chest and fly around really fast. And yes, you're exactly right. As you redistribute weight around a system, the rate of rotation can change. And that's what we're seeing with the earth. It's worth saying that the increase in the day, sorry, the increase in the rotation period is very small, right? It's less than two milliseconds faster, uh, than it was this time last year. So it's a very minute increase.

Chris - How did they actually pick that up, Matt?

Matt - The earth is under very careful monitoring, particularly from a series of radio telescopes all the way around the surface of the earth, which talk to satellites, which very accurately map the earth surface to measure the rotation. It's a technique called very long baseline interferometry that provides a very detailed look at what the surface is doing.

Chris - What will be the consequences of us having a day that lasted 1.59, milliseconds, less long than we had been accustomed to then?

Matt - Very little to be honest. There's typically like a millisecond wobble in the earth rotation period anyway. It gets faster and slower over the course of a year by around a millisecond. So I think other than being quite a cool and interesting thing and a reason to talk about the rotation of the earth, I don't think there's gonna be any actual consequences.

Chris - Because we have seen, I think the last time it happened was about five or six years ago, the addition of leap seconds to days, in order to keep our clocks lined up. Does this mean we're gonna start knocking time off again then to even things up?

Matt - Well, some people have proposed that. Yes. So, you could take a second away if there are multiple years in a row that have these millisecond quicker days and ultimately we might have to take a second away to catch up with things. Some people are not very happy about this. I know Facebook wrote an article expressing their frustration at the idea of taking away seconds from the global time system. I think it would irreversibly break the Facebook codes. And so I think they were suggesting just to change the global timekeeping system rather than changing Facebook's code.


the Versius surgical robot

14:16 - Can robotic surgery separate Siamese twins?

How robots are the future of surgery, and how they are already helping prostate operations today

Can robotic surgery separate Siamese twins?
Mark Slack, CMR Surgical, & Ben Lamb, Addenbrooke's Hospital

Robots are increasingly making their presence felt in the operating theatre, and this week we heard the heart-warming story of how two Siamese - or conjoined - twins, linked at the head, were successfully separated during a 27 hour long procedure by robotic surgery in Rio De Janeiro. Shortly, we’ll hear from surgeon Ben Lamb about how they are being used to reduce the duration of hospital stays a bit closer to home at Addenbrooke’s Hospital, in Cambridge. But first, on that operation to separate the twins in Brazil, it actually involved 2 teams, one based in the twins’ native Brazil and one at Great Ormond Street in London who worked together using virtual reality projections so they could operate remotely. One of the surgeons, Noor ul Owase, called it ‘space age stuff.’ With us now is Obstetrician and Gynaecology consultant Mark Slack, who’s also the founder of CMR Surgical, whose technology can do similar sorts of things...

Mark - Well, there was one done the day before 9/11, between Strasbourg and New York, but the company doing it laid a cable. So it was a bit of a publicity stunt. Of course, we've got the speed of light and what you get is a lag. So if a surgeon is operating in London on a patient in Sydney, when they move their hand there is a bit of a delay until you see the instrument move on the screen. But with 5g technology I'm sure we'll get there. But at the moment, what we've got is remote mentoring and remote looking after. So with my robot called 'Versius,' when we did our first chest operation because of the pandemic, our proctors and mentors couldn't travel. So the first chest case done in Germany was supervised by a surgeon in Middlesborough, in England.

Mark - And over the course of the pandemic, we did many, many more cases. And in the past, when you're learning a new procedure you either had to get a surgeon to come to your hospital, or you had to travel to visit them. And that's enormously difficult, especially when they are so busy. And now an enormous amount of Versius' introduction to new hospitals is supervised and mentored by a surgeon in another city or in another country. And we in fact have actually partnered with a British company. We've actually now created the infrastructure, so when you buy our robot, you get all this remote mentoring stuff as well.

Chris - So the point being that you are teaching people without actually having to be there, you don't have to fly people all the way around the world to sit in teaching sessions. You can teach them where you can see in virtual reality, what they're seeing, and you can have a shared learning experience.

Mark - Absolutely. So at the moment, we don't have that in virtual reality, we just have it on a screen. Virtual reality is in development but it's also worth mentioning when we train people, we train a very significant partner on virtual reality. So in the old days, if you wanted to learn a new robot, you'd have to go to the hospital and sit on one and practice. You can now sit in your lounge at home with a VR headset and play at the hand controls and practice all you want.

Chris - Nevertheless, though, if you are conducting an operation in a remote part of the world, you can have mentoring for that surgery, presumably by a surgeon who is in London, watching what's going on in Brazil. And they can see and almost experience what is happening to that patient. And they can therefore give insight. They can give hints and tips.

Mark - Absolutely and we are developing ways of communication for them so they use the same terms and so on. But a significant number of our new surgeons using the Versius robot for the first time are supervised by people in other countries and other cities.

Chris - And you said that the other people who did this laid a cable in order to make sure there were no delays or jitter or anything. Do you think it is beyond the realms of possibility that we will be entering a realm where you do get surgery conducted by people who are not in the same room as the patient they're operating on?

Mark - I think Chris, I think we will. The first step will be that the patient being operated on will have a competent surgeon in the theater, but they may not have done the complexity, like the incredible case you just described at the beginning of the piece. And the other surgeon at the moment will just say 'you shouldn't cut there' or 'you should cut there'. I think sooner than you'll imagine we'll have a situation where the surgeon will say 'can I just take control for a few minutes' and do the intricate bit, and then hand it back to the surgeon on the ground.

Chris - A bit like we do with airplanes.

Mark - Correct.

Chris - I mean, there are ways of flying aircraft remotely, and it's probably not dissimilar then.

Mark - It is, and the headsets are the one thing that's really made me see it potentially come true because then the two surgeons will be seeing exactly the same view.

Chris - Yeah. It's not like looking over someone's shoulder and getting a slightly different view. You are seeing what they are seeing.

Mark - Exactly. And so at the moment we are pretty close to that already, but the next stage will be saying 'oh, can I just take control for a second and just give you a pointer'. And then it just improves the quality of surgery and quality of training.

Chris - And just briefly, is there an additional point here? Because if you take, say, cars as an example. Cars can learn from how their driver responds to different road conditions and they share that learning with the whole fleet of cars electronically. So the cars are better at doing their own collision avoidance and so on in the future. Can your robot look at what a surgeon does, look at what it thinks it should do and then think 'well he or she did it differently. Why did they do it differently? There's a learning point there', and then share that knowledge?

Mark - You're reading my mind. The next big thing in surgery is standardization and every movement our robot does is measured and sent up to a cloud. And we actually tested it recently. We taught it to distinguish between a novice and an expert. And it identified seven out of eight of both groups, and then we looked at the videos and the one novice was pretty amazing. And the one expert wasn't so good.

Chris - And it wasn't Mark himself. You'll be relieved to hear. That was Mark Slack, he's the founder of CMR Surgical.

Julia - As we mentioned just now, robots are also helping us cut down the times patients spend in hospital. Consultant urologist Ben Lamb has had some very encouraging results with this. So Ben, what have you been using robots to do?

Ben - So we've been using robots for a number of years now to treatment with prostate cancer and it's an operation where we removed the entire prostate with cancer contained in the hope of curing them of the disease.

Julia - What is the scale of this difference then? So when you're using the robot versus before?

Ben - So traditionally doing an open operation, so a big cut down the tummy for men with prostate cancer, patients could expect to be in hospital anywhere from five to seven days with a significant amount of blood loss and a pretty slow recovery with risk of complications. The use of robotics, which allows us to get right deep down inside the patient's pelvis to the prostate, very carefully dissecting the prostate out and preserving the other good organs that you still need afterwards. It means that we, consistently and reliably at Addenbrooke's now, send patients home usually within 24 hours of their surgery. They're up the same day as their operation. They're going home the following morning. The complication rates are much lower. The recovery's faster, back to family quicker, back to work quicker, and getting back to normal life quicker.

Julia - And at the minute, is this procedure done for every patient who needs the operation or is it sort of a case by case basis?

Ben - I mean the UK's lucky actually. I think we have some of the highest rates in the world of robotic surgery for men with prostate cancer. And I think that's thanks to the organization of cancer care in the NHS. So men in the UK can expect to have this technology in their treatment for prostate cancer. I think what we've done at Addenbrooke's is to push this one step forward, use an enhanced recovery program, training nurses using the day case unit to make sure that we can do this for a hundred percent of patients getting them all home the first day after surgery.

A handshake drawn on a chalkboard.

22:41 - Gestures to make Zoom calls more bearable

New hand signals to reduce awkwardness and anxiety over video calls.

Gestures to make Zoom calls more bearable
Paul Hills & Daniel Richardson, UCL

Now, to video calls. Something we’ve all got used to and a topic we’ve covered previously on the show. They’re here to stay, so how do we get rid of some of the awkwardness associated with them? Past research has shown that being tethered to our screens during video conferences comes at a cognitive cost to idea creation, because our anxiety of appearing rude by looking away from the screen reduces our capacity to think freely. There are some suggestions that it may be better to turn the cameras off altogether. But what if there was a way to overcome the negative aspects of online interaction and reap the benefits of non-verbal communication so often lost in virtual meetings? That’s the goal of Paul Hills and Daniel Richardson of UCL, who have collaborated on a new study published in PLOS One this week. It outlines the effectiveness of a set of gestures you can use to enhance communication in your very next meeting. James Tytko heard first from Paul how he conceived the idea…

Paul - I've always found meetings very troublesome anyway. And, when we hit Zoom, it just seemed to me to get even worse. And I couldn't believe how quickly we descended into an acceptance of poor meetings. I just thought there's something in here around gestures. You know, we are talking about not being able to read the body language in Zoom. Why don't we make the body language more obvious? Could I take a handful of these signals and just try them out? You probably only need about 10 and they kind of fall into two broad camps. One camp is a gesture that shows recognition - that you are there and you're interested. And that could be the thumbs up or I could put my hand to my heart, and everyone can imagine me doing that, to show you some kindness or empathy if you've shared something with me. The other set really are about passing the conversation. And this hits the other big issue with Zoom calls, which is 'how do I know when it's my go to speak?' And also thought of the analogy of the conversation being like a ball in a team game. So, if you watch a good team with the ball, they'll have their teammates looking to receive a pass. And that's the mindset I would encourage in a meeting. You know that I'm going to want to pass soon, so look to receive. And, if you want to receive, give a big wave, a physical wave above your head, and that means please pass to me. And I'm not allowed to just stop so I would have to say, I now pass to James or I now pass to Daniel. And as teams get used to it, if I pop my hands on top of each other in a kind of banging motion, I'm saying I'm doing a build. I'm actually saying to pass me, because I want to build on your point. And you'll probably like that ,you'll think 'oh, well I will pass to Paul who wants to build'. If I scratch my head in a Laurel and Hardy type fashion, I'm saying 'please pass to me, I've got a question' - you've just said something I didn't understand and it would really help for me to go next so I can ask you my question. And I saw Daniel wave there, so I'm gonna pass to Daniel.

Daniel - I don't think of these as a vocabulary of signs, right? Because when we tell people about these, sometimes they say, 'oh is it a bit like British sign language?' How I think of them really is more like supercharged gestures. And what I do in my scientific world is study how people interact face to face. And we look at eye contact; we look at timing. We look at all of these little things you do like, mm-hmm, <affirmative> Uh-huh. Mm-hmm <affirmative>.We call it back-channeling. All of these things, we don't think of as language, but it's absolutely vital for communication and interaction to happen. And the trouble is, on Zoom, they just don't work.

James - I completely relate to wanting to give that validation through nods and things over Zoom call and I can already feel I'm part of the way there. I make them more exaggerated already, but this just gives you that extra push. My sister has recently been at university. She's done her past couple of years, a lot over zoom. And she speaks of the horror of when the lecturer, or the person in charge of the seminar says, 'right guys, we're gonna go into some breakout rooms to do some further discussion'. And she says, it's always a bit of an awkward experience. How did you go about proving that this would help to improve video calls?

Daniel - So we did a randomized trial where we picked half of our students or gave them a 10 minute training. The other half did not. We measured them, before we measured them after, we compared the sign group with the control group. What we thought was that, okay, maybe this will help with efficiency, right? If all we cared about was how quickly could we reach an agreement? How quickly could we finish this task? The signs might help because there's less sort of awkward silences, less dithering. And we also measure just simply the affiliation. Just how much do I like these guys that I've been working with? How close to them do I feel? Do I feel similar to them? Do we have that social connection? And then also we had a more objective measure. We took the speech of what was said, and we transcribed it all anonymously and we had a computer just code it for positivity. So you can literally count the number of positive and negative words. So did I say 'thank you for that Paul', or just say 'that was great, Paul, thank you so much for that', Right? You can just count the language in a very objective manner. And what we found when we compared the people out of the training with a randomly matched control group is that yes, they were more efficient, they felt like they achieved tasks more quickly. But also they just liked each other more, they liked the experience, they felt closer as a group and, sure enough, they used more positive language and less negative language as a function. These things are just making everything a little easier.

Paul - So I'm just making a gesture to say I'd like to have it passed to me and I've got another perspective or another idea. And I think you can have brilliant discussions, very creative discussions on Zoom. I don't think it has to be a barrier, but you've got to have everyone in the game. Everyone's got to be there. They've got to listen, they've got to want to talk and they've got to know when they can talk. And I think it can be better than face to face. It doesn't have to be worse in any way. And I found it takes a while to implement. You can't just sort of look at the science and think, right, we'll start using them tomorrow. It's a kind of habit changing thing. But if you get a team to commit to using them, and I usually say use them for five meetings and use them well, and then if you don't like them you can drop them. But if they're working for you, then choose to keep them going.



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