Every day, thousands of people take the Tube from the north to the south of London or the Channel Tunnel to cross the English Channel. These routes are only possible because of something very important: tunnels that are underwater. But how does someone build something so amazing?

The shield for tunneling
Before French-British engineer Marc Isambard Brunel got an idea from nature in 1818, no one knew how to build an underwater tunnel. After seeing how the shell plates of a shipworm let it cut through wood, Brunel took that idea and made the tunneling shield bigger.

In this case, it was a huge, rectangular mold made of cast iron. The walls had shutter openings that were opened one at a time so that miners could dig into the soft ground outside. The shield was then moved forward with screw jacks, and the process started all over again. In the newly carved area behind, a protective “shell” of bricks was built around the tunnel.

Because of this, the first tunnel under the water was built under the River Thames in London. It was finished in 1842. In later tunnels under the Thames, the air in front of the shield was pressed down to try to stop flooding while the tunnels were being built.

Today, tunneling shields are still used. They are round and usually made of steel, which is also used to make the support rings for the tunnel. Modern versions also use hydraulic jacks to move the shield forward. There is a door in front of the shield that can be used when it’s not moving. Shields also have a protective hood on them for the people who go out to work there.

Machines that dig tunnels
Of course, digging through soft ground is one thing, but boring through rock under the water is something completely different. In this case, tunnel boring machines (TBMs), which were used to build the Channel Tunnel, changed the rules of the game dramatically.

The tunneling shield and the TMB both do the same thing, but the TMB uses a mechanical spinning cutting head to dig through the rock in front of it instead of people. It does this by putting stress on the rock, which breaks it up. There is no need for people to move the broken rock out of the way because it is taken back on a conveyor belt.

There are eleven TMBs that were used to dig the three 56.3-kilometer (35-mile) long tunnels. Some parts of the tunnels are 45 meters (148 feet) below the surface of the water.

Tunnels with immersed tubes
In the first two methods, the tunnel walls are built as the work is done, but there is another way to do it. Immersed tube tunneling is another method. W.J. Wilgus, an American engineer, was the one who created it.

With this method, the tunnel is built somewhere else first, with several sections already built, while a trench is dug into the riverbed or seabed where the tunnel will go. The pieces are then floated to the spot and sunk into place. The water is then drained from them, and dirt from the excavation is put on top of the tunnel to bury it and make the bed level again.

People have been interested in the Antikythera mechanism for more than 120 years, and new research has shed more light on this amazing machine in recent years. The pieces that are still there show that it was probably used to figure out things like eclipses and where the planets were in the sky. With some statistical methods that are often used in gravitational wave research, astronomers from the University of Glasgow have found more proof that it is linked to the Moon.

Professor Graham Woan and Dr. Joseph Bayley each used a different method after an interesting X-ray analysis of the object was done years ago. Some people don’t know how many holes are in one of the rings, which is thought to be a calendar. There is only a small piece of the ring left, and it’s hard to say for sure what it is because it spent 2,000 years underwater.

Based on the X-ray data, Woan and Bayley used bayesian statistics to determine how many holes there were in the rings. The most likely number was either 354 or 355 holes, they found. Around 354 days make up a lunar calendar. Based on the research, this number is 100 times more likely than 360 holes, which is what the Egyptian solar calendar has. This means that a 365-hole ring, which would be like a real solar year, is very unlikely.

“Towards the end of last year, a colleague showed me data that YouTuber Chris Budiselic had collected. Budiselic was trying to make a copy of the calendar ring and was looking into ways to find out how many holes it had,” Professor Woan said in a statement. “I thought it was an interesting problem that I might be able to solve in a new way over the Christmas break, so I started using some statistical methods to find the answer.”

The Markov Chain Monte Carlo and nested sampling methods were used. These are common ways to figure out how likely one result is given incomplete data. These techniques lead us to believe that the whole ring was 77.1 millimeters across and had either 354 or 355 holes spaced 0.028 millimeters apart.

“Previous research had suggested that the calendar ring probably followed the lunar calendar, but the two methods we used in this project make it much more likely that this was the case,” Dr. Bayley said. “It’s made me appreciate the Antikythera mechanism and the work and care that Greek craftsmen put into making it even more. To punch the holes so precisely, they would have needed to be measured very accurately and punched with a very steady hand.”

The study has been written up in The Horological Journal.

A group of YouTubers have created a remarkable retractable lightsaber that they classify as “potentially hazardous.”.

HeroTech recently released a video outlining their intention to develop a lightsaber that mimics the retractable nature of the lightsabers seen in the Star Wars movies, as opposed to the currently available models with fixed extended blades.

The team stated on YouTube that they were well aware of the challenges they would face when embarking on the project to create an actual retractable lightsaber. “Our primary obstacles were evident: achieving complete containment of blade extension and retraction, creating a compact hilt design that is proportional to the original, and producing a blade and sound that closely resemble reality.”

Creating a retractable lightsaber proved challenging, but the team successfully accomplished this by utilizing a magician’s cane, a tool that can contract to a compact size and extend to a length of over 0.9 meters (3 feet). After extensive tinkering, the outcome is a remarkable lightsaber that elongates upon activation.

The team clarifies on their website that this lightsaber showcases a dazzling blade of light that genuinely extends from and retracts into the hilt. “Equipped with a 12V COB LED strip, 4S LiPo battery, the Proffieboard V3.9, and a high-performance speaker, this lightsaber delivers authentic lighting effects and lifelike sound effects.”

The team also aimed to enable others to construct the lightsaber in their own homes, by furnishing their subscribers with comprehensive instructions on how to do so. Nevertheless, they have strongly cautioned against attempting it.

“This lightsaber is an experimental model and has the potential to be hazardous if attempted to be made by oneself,” they mention on their YouTube channel. “Although I am actively working towards improving this situation, I am unable to currently endorse this product for individuals lacking engineering proficiency and the determination to spend several hours resolving technical issues.”

Disney has developed its own collapsible lightsabers specifically for use in performances at Disney World, although they are probably not produced at a low cost.

Neither of the blades is capable of cutting through stormtroopers, as they are purely ornamental. Nevertheless, an inexperienced YouTuber successfully constructed a functional lightsaber with the ability to retract, earning a place in the Guinness Book of World Records in 2022.

Alex Burkan, the proprietor of the YouTube channel Alex Lab, engineered a contraption capable of generating a plasma blade measuring 1 meter (equivalent to 3.28 feet) in length upon activation. The blade, which reaches a temperature of 2,800°C (5,072°F), possesses the ability to effortlessly slice through steel.

“An electrolyser is the crucial element of my lightsaber,” Burkan informed Guinness World Records. An electrolyser is a device capable of producing a substantial quantity of hydrogen and oxygen, and it can compress the gas to any desired pressure without the need for a mechanical compressor.

However, in contrast to an authentic lightsaber or the ones demonstrated by Disney, the blade has a limited operational duration of approximately 30 seconds at maximum intensity. Consequently, lightsaber duels are brief unless they occur in close proximity to charging stations.

Burkan also mentioned that occasionally the lightsaber may explode in your hand due to a hydrogen flashback.