Category: Systems

H2 is difficult

I mentioned Hydrogen as an option for aviation. The use of Hydrogen to either power jet engines or to power fuel cells to provide electricity is a real technical option. Although the person I was talking to was engaged in environmental work, they shrugged their shoulders when I mentioned Hydrogen. They were certainly not impressed by these possibilities despite our agreement on the urgent need for de-carbonisation.

I can understand why there’s a level of cynicisms. On my part, it’s like the X-Files[1]. Fox Mulder was the believer and Dana Scully the sceptic. Broadly, I want to believe.

Today’s, liquid fuels can be explosive in certain conditions. However, it takes a considerable effort to create the conditions whereby a devastating explosion can occur. The Boeing 747-100 that was Trans World Airlines Flight 800 (TWA 800)[2] exploded, broke up in the air and fell into the Atlantic Ocean in 1996. This was an example of a worst-case scenario. 230 people were lost in that fatal accident. Now, the ignition of a flammable fuel/air mixture in aircraft tanks is better prevented by design and operational procedures.

If Hydrogen is to be viable in civil aviation such hazardous conditions will be harder to prevent. A flammable hydrogen/air mixture can be ignited much more easily than conventional liquid fuels. Such dangerous situations can be prevented but the measure to do so will require robust design and stringent operational procedures.

Several development programmes are underway, making practical Hydrogen powered aircraft viable. A range of aircraft configurations are possible. From hybrid generator and electric motor set-ups to combustion-based propulsion. This work is moving from academic research into commercial possibilities.

There little read across between the behaviour of conventional hydrocarbon liquid fuels and liquid Hydrogen. This would be evident in any serious incident or accident scenario. Let us imagine the case of British Airways Flight 38, in 2006, a Boeing 777-236 that came down at the end of a runway at London Heathrow[3]. A significant amount of fuel leaked from the aircraft after it came to rest, but there was no fire. There were no fatalities.

The breakup of liquid Hydrogen tanks or plumbing in such a scenario would almost certainly result in a significant fire. The mitigating impact of that fire is the lightness of the gas. Instead of liquid fuel pooling on the ground, Hydrogen would burn upward. However, any explosion could be devastating.

So, for large aircraft design the provisions to protect liquid Hydrogen tanks and plumbing must be extensive and extremely robust. This would have to be maintained, as such throughout the whole operational life of the aircraft. These requirements would be onerous.

Keeping crew and passengers well away from Hydrogen infrastructure will be a must.

POST 1: Crashworthiness doesn’t get much of a look-in. Without it there’s going to be a problem over the horizon. https://www.ati.org.uk/flyzero-reports/

POST 2: At least for eVTOL aircraft some work is being done. https://ieeexplore.ieee.org/document/10011735

[1] https://www.imdb.com/title/tt0106179/

[2] https://www.history.com/news/twa-flight-800-crash-investigation

[3] https://assets.publishing.service.gov.uk/media/5422ec32e5274a13170000ed/S1-2008_G-YMMM.pdf

2053, not so far off

Language is marvellous. We have all sorts of ways of expressing ups and downs, goods and bads, dreams and realities. This week this slogan caught my eye: “Our third decade of climate action”. I didn’t know whether to be impressed or to think that’s a long time given how little we have achieved. I suppose both responses are off the mark. Neither should I be impressed or dismissive of what has been done in the last 30-years.

Now, “sustainability” is a word[1] that gets banded around like confetti. That certainly wasn’t the case in 1990. That’s not to say there wasn’t a green movement. Public awareness of the need to change was triggered in the 1970s. It’s only that what was a minority interest is now a mass interest.

If the multiple crises of the 1970s had motivated sustained change, then there’s no doubt we would be in a hugely better place than we are now. A great number of projects would have matured and alleviated the globes environmental burdens. New markets would have developed.

The observation I have is that rather than adopting the tough route of positive change, instead we took the easier path of going for the low-cost option. Oil and gas were as alluring as chocolate and sunny summer beaches. Does this tell us anything useful about human nature? Loads of memes scattered around social media would like us to think so. They are hardly profound. Mostly bland.

Language is marvellous. There’s a catalogue of famous speeches that mark moments in history when change happened. Or at least, times when many people pivoted from one position to another. Powerful words can transform.

Our problem in 2023 is that we are saturated with noise. Endless reassurances that big organisations pump out tell us how well we are doing. Brave politicians implore us to move in a different direction. Campaign groups thrust “in-your-face” activist at us. Sadly, the collective effort is culminating in many people switching off. There’s the real danger that the next 30-years will experience a sluggish movement and even a dumb reversion to past practices[2]. It’s a prospect that hovering in plain sight.

Language is marvellous. What we need, at this moment in history, is not more words but some truly meaningful words that motivate real change. Future generations, and it’s unlikely that I’ll be here after the next three decades, but not impossible, must not be left with an enormous mess brought on by our reluctance to change. Oil and gas are not the future. We must not put off the day we wean ourselves off these two.

[1] https://www.un.org/en/academic-impact/sustainability

[2] https://www.gov.uk/government/news/hundreds-of-new-north-sea-oil-and-gas-licences-to-boost-british-energy-independence-and-grow-the-economy-31-july-2023

Short-sighted

None of that comes cheap.

OK. Why are mini-nuclear power stations such an irrational idea? The industry is selling these untried, untested power station as completely unlike that which has gone before. A Conservative Minister has been echoing their marketing brochures.

Let me say, with power generation there are some basic realities that remain the same.

Fuel must be transported to power stations and waste must be removed from them on a regular basis. For coal, that was the reason for the sitting of large power stations in the past. For gas, there was more flexibility in location, but the costs of transportation still needed to be minimised. For such innovations as waste-to-energy plants, proximity to the source of waste presented a major problem. Neighbourhoods rarely invited these plants to be built close by.

Spreading the distribution of nuclear fuel and waste around the country doesn’t sound like a good idea to me. Cost of transportation are high. Safety is paramount. Security is always a grave concern.

Now, I understand the need for limited numbers large-scale nuclear power stations. They provide a reliable base load when the renewable sources of power are not available. The wind doesn’t blow.

Although, there are a variety of different international companies in the nuclear business the notion of a “free market” in the conventional sense is not a real prospect. The investments needed to be competent and meet regulatory requirements in the nuclear business are huge. Projects are there for the long-term. A whole working career of a nuclear engineer may be locked to one technology.

Experience has shown us that a goal of zero accidents rarely delivers a reality of zero accidents. These are complex engineered systems. It doesn’t matter if they are big or small the complexities remain. Yes, safety can be managed in a safety critical industry but there had better be preparedness for worst possible outcomes[1]. With these nuclear plants decommissioning and recovery from significant incidents of contamination must be accounted for in any design, implementation, and operation. None of that comes cheap.

Overall, in Britain there are much better paths to travel than the mini-nuclear one.

It absolutely astonishes me that, given the enormous tidal range of the Severn Estuary[2] we have never captured the energy of those waters. Equality in a nation, with a coast as large as ours, we have only ever dabbled in wave power[3]. Let’s have some genuine innovation. Let’s think like the Victorians and build for the long-term.

Why are we so incredibly short-sighted in Britain?

[1] https://www.bbc.co.uk/news/world-13047267

[2] https://en.wikipedia.org/wiki/Severn_Barrage

[3] https://en.wikipedia.org/wiki/Salter%27s_duck

Bad Smell

Where is the accountability?

My desk, that’s the one in the early 1990s, faced towards the London Gatwick airport approach. It was a good reminder of the business we were in at the time. Seeing aircraft land and take-off about 500 m from the sheet glass windows of our office block was the daily background. Being in a rugged hermetically sealed building aircraft noise wasn’t a great concern.

Little more than 300m from the building and looking in the same direction was, and still is, the Gatwick sewage works. Its structures were low rise, so it was often hidden behind the greenery. Every so often, a strong wind would blow from the northeast. When it did a distinct odor filled the air. Yes, you guessed it. The sweet smell of the sewerage works would permeate the air conditioning.

This odor was at its most notable in the metrological conditions called an inversion[1]. In fact, given the seasonal frequency of these weather conditions it could be said that Gatwick wasn’t the most sensible place to build a major airport. These occasional pongs were a bit of a joke. Along with the occasional smells of unburnt aviation fuel it was just life at the airport. Lingering odors didn’t stay for long. A day at most and the wind would change direction back to where it normally came from – the south west.

Airports and sewage works are not a good combination for the health of rivers and streams. Long ago, when Gatwick airport was built the tributaries of the River Mole[2] were diverted. The part of that river, the Gatwick stream going north to south, at the end of the runway, is an unattractive V-shaped gully. Not nice for nature at all. There was a track that ran parallel with the river. In the summer, I’d walk that track at a lunchtime as it was a way of getting to the airport’s south terminal.

In the news, Thames Water are being fined for dumping raw sewage in the River Mole[3]. The consequences of the UK’s water regulator[4] taking a relatively hands-off approach to managing water companies, since privatisation in the late 1980s, has come home to roost.

I must admit, I’m not the least bit surprised. So far, the dance of those who shrug their shoulders astonishing. Ministers, regulators, company chiefs are all pointing fingers at each other.

The sequence of events is mind blowing when looked at over several decades[5]. Chief executives attracting massive salaries. Companies being loaded up with debt. Generous payouts to shareholders. Investments in infrastructure not keeping pace.

Ofwat, the regulator talks with incredible complacency. Such weak regulators are no more than a piggy in the middle as the powerful forces of unethical commercial behaviour and disinterested government oversight combine. As millions of families struggle with the cost of living this kind of failure is intolerable. Where is the accountability?

[1] https://www.metoffice.gov.uk/weather/learn-about/weather/types-of-weather/temperature/temperature-inversion

[2] https://www.southeastriverstrust.org/river-mole/

[3] https://www.independent.co.uk/news/uk/crime/thames-water-sewage-spill-gatwick-airport-b2368707.html

[4] https://www.ofwat.gov.uk/

[5] https://www.bbc.com/news/business-66103356.amp

Getting smaller

We are on an unstoppable rollercoaster.

We don’t use the word miniaturisation much. I wonder why? Everyday we take for granted incredibly powerful handheld computing machines. They are only possible because of miniaturisation.

If digital signal processing was your thing in the 1970s, it would have involved several heavy cabinets of electronics. Lots of chunky circuit boards and a reliable way of removing all the heat they generated. As an example, there’s a nice dusty relict of a Cray computer[1] in the Science Museum in London. Later, I’ll read this again on a popular handheld device that has innumerable functions. Just as powerful.

This week, in 2007 the first iPhone was launched[2]. With a reasonably sized touch screen and a camera, it was launched with lots of hype. Rapidly this device started to change not only the marketplace for phones and cameras but the way we live, work and play.

I wasn’t a first adopter. At the time, I think I was faithful to Nokia. But somewhere in a cupboard, I still have an iPhone 3G, the successor to the first iPhone. 16-years on, it feels like there was never a time when we didn’t have the iPhone, or one of its competitors.

Miniaturisation has squeezed capable and flexible digital computing into small spaces. It’s made it possible to concentrate multiple functions into one device. The sheer convenience of that has crushed the non-professional camera marketplace. Streaming music has superseded traditional media, like tape and disks, almost to the point of their extinction.

The societal implications of this technological transformation are much talked and written about but maybe read by few. It’s fascinating to speculate if we have come to the end of Moore’s law[3]. That’s the empirical relationship that seems to hold for semiconductors. So far, Moore’s prediction has held-up well for the semiconductor industry. As the density of semiconductors doubles about every two years, so nothing ever stands still.

We might shrug our shoulders and carry on as if nothing has changed. Or just not care to look at this phenomenon, thinking its irrelevant to the important political machinations of the day. However, the impact of the steps that have led to more and more dependency on personal devices is something we should be concerned about. There’s little, or no possibility of reversion back to more manual ways of doing business. We have been captured by the convenience of affordable internet connected handhelds.

Decarbonisation is the big policy of the day. Miniaturisation is a two-edged sword in this respect. More people, holding more devices, in the billions, which are regularly superseded by the next upgrade all has a downside. Not only that but networks and massive file server farms backing-up the internet as they hungerly consume ever more energy. Thousands of new satellites mean instant connection on any part of the globe.

We are on an unstoppable rollercoaster. We think we have a choice but we don’t.

[1] https://www.computerhistory.org/revolution/supercomputers/10/7

[2] The first iPhone Release Date: 29 June 2007.  

[3] https://en.wikipedia.org/wiki/Moore%27s_law

Design

Forewarned is, fore armed.

Getting it right by design matters. If a designer gets it right, then everyone who follows gets what they expect. Why am I writing these words? Well, a dumb message has come up on my computer. What I call dumb is a message that tells me something has happened but gives me no clue as to what to do next. It’s about as useful as a chocolate fire guard as they say.

Messages like: “Operation failed with unexpected error” in the top right of the screen are not helpful. Pop-ups like this are an indication that this is not a good design. It’s a kind of catch all statement that means we haven’t got a clue.

The usual response to such a message is to start over again in the hope that this is a one-off occurrence. So, that’s what I did. Guess what the same situation occurred. Not having a better strategy available, I did the same again. Same result. Thank you, Microsoft Teams.

While I’m on about that company another small but annoying bugbear comes to mind. Microsoft Mail works well enough. However, a forced error happens every so often. I find that I’ve deleted a message that I’d intended to flag to remind me to do something. A hunt for the message usually finds it mixed up with the pile to be deleted. When the delete button and the flag button are next to each other this error is almost inevitable. Why did the designers do this foolish thing?

I’ll not beat up on Microsoft too much, given that just about every software company has one of two of these annoyances to ruin your day. Good job my personal safety doesn’t depend on this stuff, I say. So much for commercial off the shelf software in 2023.

A video scrolled up on my iPad. It was that man who likes to take machines apart: James May. A couple of million people have viewed his video titled: “James May’s Tesla Model S has failed![1]”

It’s a good reminder that designers need to think about situations that go badly as much as they need to think about them going well. Vehicles do sit around in garages. Not everyone is used every day. It’s not the fault of the owner if they do not run the vehicle for a while.

Electrification is great when everything works. However, a simple manual reversion should be available when the electrics are not there to do their thing. Afterall, we don’t yet have a reliable battery that lasts forever. The door won’t open because the battery’s flat is as useful as the message highlighted at the start of these words.

Oversights during the engineering design process happens when the pressure is to get a product to the marketplace as quickly as possible. Maybe this is one of them to look out for in future. I will not be smug. This sort of obvious when you know it flaw is as likely to happen in aviation as it is in other industries. Forewarned is, fore armed.

There are also the wonders of feedback. Having made a design error, it’s mechanics who often uncover it, figure it out and then find a fix. This is a shout out for easy and open reporting.

[1] https://youtu.be/NsKwMryKqRE

Titan’s fate

Firstly, condolences to the families and friends of those who perished in the deep ocean last week. This fatal tragedy took place in the full glare of the public spotlight. It’s time to give those affected time to grieve for their loss.

I will address the subject of vehicle safety in a technical manner. It’s immensely sad when what is known must be re-learnt in such a tragic way. By their nature, passenger vehicles that enter hostile environments will present high risks. There is always a likelihood of an event of significant severity as to cause injury. The imperative should be to reduce that probability as much as possible.  

The Transportation Safety Board of Canada (TSB)[1] has launched an investigation into the events that led to the loss of the submersible called: Titan. That organisation will do a detailed investigation into the reasons behind the accident that led to the deaths of five people on-board. 

There’s much conjecture about the factors involved in this catastrophe. News media and social media are awash with speculations. The facts are that contact was lost with the Titan’s support vessel and a catastrophic event took place[2].

What has come to light in the aftermath of this event is the public statements made by the driving force behind the Titan project. This has been contrasted with the those from the submersible community who spoke out on their concerns about the project.

My reflection on this information is to say that – safety starts at the top. If the entrepreneurs who promote these adventures are not literate, humble, and vigilant then outcomes are going to be negative. Those in leadership positions need to listen to those with expertise in their field of endeavour. Accepted, that it’s not the case that everyone will agree all the time about operational and technical risks but an open dialogue is vital.

I know that innovation often takes the path of trying, failing, trying again, failing, and trying again to eventually succeed. However, no vehicle should enter public service without sufficient proving.  Independent oversight adds value too. The cultural framework within which this happens shapes success or failure. That’s why there’s good reason for design certification. That’s to apply time and energy to extensive testing, applying recognised standards and listening to reputable expertise. At its best it’s an opportunity to draw on widespread experiences from the past – good and bad.

Systems that prove to be safe most often come about from those who take on knowledge, experience, and learning. Yes, this work is not free. It can cost much to go from theory to practice. When the impact of failure, when the outcome is tragic for families, loved ones and colleagues these expenses are not so large.

We must take every opportunity to learn from such fatal accidents to make them extremely rare. 

#Safey Management #SystemSafety #HumanFactors #SafetyCulture

[1] https://www.tsb.gc.ca/eng/medias-media/deploiement-deployment/marine/2023/m23a0169-20230623.html

[2] https://www.tsb.gc.ca/eng/enquetes-investigations/marine/2023/m23a0169/m23a0169.html

Sound in Water

We are all used to what light does around us. For the most part light travels in straight lines. I see you because of the light reflected off you. With our stereoscopic vision, I can estimate how far away you are from me. So, humans are equipped to detect range and direction. That’s incredibly useful in everyday life. We’ve evolved with a good ability to sense of our local environment.

We have two ears. So, to a degree we can judge the direction a sound is coming from in the air. That does get more complicated as the wind blows, with reflections and other noises clutter up our environment. How far away something is presents us with guess work. In the dark, a loud person close to us isn’t too difficult to guess. A quest person, far away is much more difficult to guess.

Sound in water behaves with some of these characteristics but temperature has a significant impact.

Our human experience of sound in water isn’t all that good. That’s down to the interface between air and water. For us water is not our natural environment. Our ears are attuned to sounds in the air.

There’s a device called an expendable bathythermograph (XBT). A nice title that makes this device sound high-tech and whizzy. The truth is that it’s remarkably simple. It’s a thermocouple, for measuring temperature at the end of a long wire that uncoils as it descends in water.

Thrown overboard at sea, the XBT sinks. At the surface a chart is drawn of the temperature profile of that point in the sea. Knowing the temperature profile, it’s possible to calculate what the sounds will do in that seawater. There are variations in the speed of sound in water with temperature.

Key factors to consider with the propagation of sound in water is pressure and temperature. Depth and pressure are simply related. Salinity has an impact too but that’s not the major factor at greater depths. At the deepest point in the sea the temperature is relatively constant.

A student project of mine was to design a sound velocity meter for use in the sea. The idea was to directly measure the speed of sound in water. It was what’s called a “sing‐around velocimeter.[1]”

What all this amounts to is that sound may not travel in a straight line in sea water. So, if a sensor on a surface boat picks-up a sound it may not be so easy to say where it’s coming from without a lot of additional information.

Those searching for the missing submersible in the North Atlantic are aware of the tricks that sound can play in seawater. Let’s hope that the sounds that have been reported as being detected prove to be useful in finding those in peril.

[1] https://pubs.aip.org/asa/jasa/article/85/S1/S112/649512/Measurement-of-the-sound-speed-in-air-by-sing

Build-A-Car

How many people do you know who have taken a sharp axe to a Morris 1000[1] van? It’s a surprisingly effective tool. It was a hot day. The task took a fair degree of persistence. Nothing for an energetic 16-year-old.

What I was doing was to cut out the front sub-frame complete with the suspension complete. The van differed from the construction of the car by having a separate chassis. The Morris Minor had a straightforward torsion bar front suspension. Corrosion can be a real problem with these cars, but this old grey van was structurally sound.

The reason? For popular cars of its era, it had a ruggedness and simplicity that made it easy to work with and, I suppose, we got hold of an MOT failure with ease and probably little money. Besides a working BMC “A” series engine always had a value.

After the careful attention of my axe the remaining parts were to become the rear part of a car that we were building at school. That Morris 1000 front end would be welded to a Triumph Herald[2] front end. We didn’t do that. Our friend, mentor and teacher did the welding of the two chassis components. It was another year before I picked up that useful skill.

Why a Triumph Herald? That small car had a tight turning circle. I think it was about 28 feet. Funny, what gets remembered. That, and its availability in 1976 were the reasons it was valuable to my school friends and me. Putting all that together formed the basic frame of a car. Four wheels, brakes, steering and suspension. It was an ungainly looking crude construction, but it did the job. It was a good start. 

What came next was an engine. This really was a version of that story from Johnny Cash’s[3] “One Piece At A Time.” No, the engine didn’t come from a Morris or a Triumph. It came from a Reliant[4].

That question of why comes up again? Well, the Reliant engine we had got out hands on was made of aluminium. It was considerably lighter than the engines of a Morris or a Triumph. The baby Reliant engine we had was bathed in oil. It took a good kicking to get it to spark into life. I recall trying to fix brackets for engine mountings. It was an exercise done by eye. Getting the engine to run smoothly and without too much vibration was fun.

What was entity novel for a small car was our transmission system. I don’t know how this came about but we wrote to Volvo asking for them to sponsor our school’s project. They did. They provided our school with a hydrostatic drive system. That’s the pumps/motors and the assorted hydraulic plumbing. The removal of a mechanical transmission with fixed gears was the benefit we were promoting. Hydrostatic transmissions were used in boats and construction machinery but not in a small car.

All of this was stored in a tin shed at our school. Without the stubbornness of our teacher this project may have fallen into the wilderness, but we kept the faith. As I left school the project was handed on to the next generation. It was mobile. It worked, after a fashion.

The basic car became an entry in the BP Build-a-Car competition in October 1976[5]. This was a national competition where schools around the country designed and built a “practical” 2-seater car. The prize was a new school minibus. So, the competition attracted some capable, smart, and well-resourced schools.

I’d started an apprenticeship by then so didn’t get to go on the trip to the Royal Electrical and Mechanical Engineers (REME). This was the site for the contest to show off what the cars could do.

It was reported back to me that some of my designs for an electronic dashboard using LEDs attracted the interest of the judges. At the time Lagonda were ready to take on the world with a bold new design and a car with electronic instrumentation[6].

Later in my career, aircraft cockpit instrumentation design and integration were a big feature.

NOTE: I suddenly have more respect for Rick Astley. Just watch She Makes Me (Official Music Video)

[1] https://www.mmoc.org.uk/

[2] https://www.autoexpress.co.uk/classic-cars/104977/triumph-herald-buying-guide-and-review-1959-1971

[3] https://youtu.be/Pv8yTqjYCGM

[4] https://www.reliant.website/history.shtml

[5] https://youtu.be/evDWFB58Vo0

[6] https://www.auto-data.net/en/aston-martin-lagonda-ii-5.3-310hp-3052#image3

Bad Moon

Despite climate change, economic downturns, war, and recovery from a pandemic no one was prepared for, this is a good time to be alive. We are a long way from the end of days. Or at least I hope we are.

The past is another country. Only that can be said of the future too. The difference is a record book. Behind us we have the chronicles, from the first written words to this next key I’m about to tap. In front of us spreads a great deal of uncertainty.

What’s with the gloom and doom? Media of all kinds seems to bathe in a pool of pessimism. I can hear Creedence Clearwater Revival singing Bad Moon Rising[1] in the background. Despite climate change, economic downturns, war, and recovery from a pandemic no one was prepared for, this is a good time to be alive. We are a long way from the end of days. Or at least I hope we are.

In so far as fiction is concerned, I love a good dystopia. Unfortunately, some of the movies on this theme are quite ridiculous or dammed right annoying. The Day After Tomorrow[2] is a bucket load of piety and the remake of The Day the Earth Stood Still[3] has me throwing things at the TV.

Last night, I tried to get through the first half of a more recent movie called Reminiscence. It does amaze me that what must have seemed like such good ideas on paper can be transformed, at great expense, into a relatively average film. Yes, we are going to have to cope with rising sea levels and it will change the way people live.

What I’m addressing is the assertion made by a journalist who covers the cultural effect of science and technology[4]. It’s basically, that all this focus on the end of the world stuff stops us from planning a positive future. I can quite understand the basis for such a proposition.

Dare I make a HHGTTG reference? Well, I’m going to anyway[5]. It’s that society collapses if we spend all day looking at our feet, or to be more precise our shoes. Looking down all the time is equated with being depressed about the future. That leads to people buying more colourful shoes to cheer themselves up. Eventually, that process gets out of control and civilization collapses.

For someone like me who has spent a lot of time looking at accidents and incidents in the aviation world, I’m not on-side with the notion that bad news leads to gloominess and then immobility. I guess it does for some people. For me, it’s almost the reverse.

What we learn from disasters and calamities is of great benefit. It stops us from making the same mistakes time and time again. Now, I know that doesn’t last forever. Human memory is not like a machine recording. We are incredibly selective (hence films like Reminiscence).

In my mind, none of this persistent immersion in stories with bad outcomes stops us from planning. To be positive, it stops us taking our plans for what we can do into the realms of pure fantasy. Or at least it should.

[1] https://youtu.be/zUQiUFZ5RDw

[2] https://en.wikipedia.org/wiki/The_Day_After_Tomorrow

[3] https://en.wikipedia.org/wiki/The_Day_the_Earth_Stood_Still_(2008_film)

[4] https://www.newscientist.com/article/mg25834380-100-why-we-shouldnt-fill-our-minds-with-endless-tales-of-dystopia

[5] https://hitchhikers.fandom.com/wiki/Shoe_Event_Horizon