Posts Tagged‘video’

Wave Superpositioning.

Wave interference is a relatively simple scientific concept that can be difficult to grasp at first. Many are introduced to the idea in high school or college physics, usually being shown something like the double slit experiment. Whilst this is a great demonstration of the wave properties of light it’s not exactly obvious how the constructive and destructive interference actually works. Something like the following video, I feel, gives a far better visual impression of what wave interference and superpositioning does in the real world.

The really cool demonstration comes in at about 55 seconds in where they demonstrate a concentric wave singularity, or what they call “The Spike”. Basically they make the waves work in such a way that once they meet in the middle they all interfere with each other at just the right point. This results in the rapid formation of a cavity in the middle which is then slammed shut as the waves return to their peak. The resulting geyser flows upward for far longer than you’d expect it to which is a great demonstration of the power of constructive interference with waves.

FloWave itself was constructed to replicate currents and waves seen in the ocean. This allows companies and researchers to test out their technologies in a controlled environment before they get deployed offshore, potentially saving costly repairs and re-engineering. That means that it’s mostly used to test out how things respond to various kinds of waves and currents, rather than generating awesome wave spikes that shoot water several stories into the air. Still I’d love something like this on a smaller scale to do my own demonstrations of wave interference.

Bouncing Ball Bearings Beautifully.

Some of my favourite demonstrations of scientific principles are ones that you expect to behave one way but, in reality, act completely different. To me this demonstrates the value of experimentation and observation as you can never be sure until you do something for yourself. It also usually means that there’s some kind of interesting physical phenomena at play that I’m not yet familiar with, something which usually means an enjoyable trip down a Wikipedia hole. The following video is one such demonstration, showcasing an interesting property of amorphous metals.

In this demonstration (the whole channel is worth watching by the way) we can see the difference between an amorphous metal surface and a traditional one when a ball bearing is dropped on it. The difference in bounce height is quite staggering, enough to make you think initially that there’s some form of spring hidden in the cylinder. The actual reason for the difference, which is briefly touched on in the video, is far more interesting than it being a simple trick.

The material that the atomic trampoline is made of has some rather unique properties. Regular metals are usually of a crystalline structure meaning that their component atoms are highly ordered. Amorphous metals on the other hand (sometimes referred to as metallic glass) have a highly disorganised structure, owing to the fact that they’re usually alloys (made up of several different metals) and their creation process stops the formation of a crystalline structure.

This disorganisation prevents the formation of defects called dislocations which appear in crystalline metals. When a ball bearing strikes the regular metal surface these dislocations glide through the other parts of the metal’s structure, dissipating a lot of the energy. In the amorphous metal however there are no such dislocations and so much less of the energy is lost with each bounce. Of course the lack of dislocations does not negate other losses due to sound and heat which is why the ball bearing doesn’t bounce infinitely.

What I’d love to see is the same experiment redone in a vacuum chamber with both the ball bearing and the surface made from amorphous metals. I’m sure we could get some really absurd bouncing times with that!

Dry Ice Screaming.

Dry ice is a very interesting substance, both from a scientific and “it’s just plain cool” point of view. Many are familiar with the billowing clouds of smoke it can produce when placed in water, seemingly a staple of anything that needs to be made to look spooky. Others will know it for its culinary applications, able to cool things down far more rapidly than any fridge or freezer. However whats less understood is the mechanisms of how dry ice actually works which is what can produce some rather interesting effects like those shown below.

Dry ice is the solid form of carbon dioxide which, thanks to its useful properties, has found many everyday applications. It’s also quite easy to manufacture as carbon dioxide is a byproduct of many other processes. This gas is then trapped and pressurized, changing it into a liquid form. Then the pressure is released, causing some of the liquid to boil off which rapidly cools down the remaining liquid. This then forms a kind of carbon dioxide snow which can then be compressed into blocks or small pellets. Industrial applications often use the large blocks whilst the pellets are used in more everyday applications.

The video above demonstrates a property of dry ice that’s not completely obvious if you don’t know what to look for. Carbon dioxide doesn’t have a liquid state at atmospheric pressures which means that it transitions directly from a solid to a gas, bypassing the liquid phase. This process is called sublimation and means that the entire surface of dry ice is constantly emitting carbon dioxide gas. When you put something on top of it, like a large metal part shown above, the gas has to squeeze past the surface in order to escape. This is akin to pulling the ends of a balloon apart to make that loud screeching noise which is why this part appears to “scream”.

There are many other videos of people producing similar effects with dry ice and other metal objects like spoons and pennies. One interesting thing I noted from some of the other ones that the screaming effect would often stop after a short period of time. I believe this is due to the metal’s temperature approaching that of the dry ice which means that the dry ice no longer sublimates. The part in the video above is likely carrying quite a bit of heat which is why the screaming continues on for so long.

Quite fascinating, if I do say so myself.

Struggling Against Static Electricity.

Everyone knows the standard static electricity experiment. You grab yourself a perspex rod and a wool cloth and, after some vigorous rubbing (often with a few innuendos thrown in), suddenly your perspex has the ability to attract pieces of paper. Most people will also understand the mechanism of action, the transference of charge that leaves the rod negatively charged and the cloth positively charged. What most people won’t know however is that friction isn’t required to generate a static charge. This is what can lead to hilarious situations like the one in the video below:

So if friction isn’t a requirement for generating a static charge how do these address labels get it? The answer is actually pretty interesting and has to do with the way adhesives work. For these address labels the adhesion comes from a chemical reaction, meaning that the address labels had a form of bond with the backing before they were torn apart. When this bond is broken both materials will gain or lose electrons, depending on where the material sits on the triboelectric series. I’d hazard a guess that the material that the address labels is made up of tends more towards the negative end of the spectrum, meaning that bin holds a strong negative charge.

This is what is responsible for the labels floating around in a seemingly random fashion before ejecting themselves out onto the floor. The effect wouldn’t have been immediate, each label would only carry a small negative charge, however past a certain point the negative field would have become big enough to repulse the small weight of each of the labels. If they were so inclined they could throw a positively charged piece of plastic in there and they’d all be attracted which would also be pretty interesting.

Or, if you wanted some real fun, if they rubbed their head with a balloon and then dunked themselves in there all the labels would gleefully stick to them. Not that that proves much, just that it’d be hilarious to see someone with shipping label backing stuck to them.

Linear Friction Welding of…Wood?

Friction welding is a fascinating process, able to join dissimilar metals and plastics together with bonds that are far stronger than their welded counterparts. As far as I was aware though it was limited to inorganic materials, mostly because other materials would simply catch fire and not fuse together. As it turns out that’s not the case and recent research has shown that it’s possible to friction weld pieces of wood together in the much the same way as you would metal.

What’s particularly interesting about the process is how similar it is to friction welding of metals or plastics. Essentially the rubbing of the two surfaces together causes the interfaces to form a viscous film that mixes together and, when the friction is stopped, fuse together. For the above video you can see some of the film produced escaping through the sides due to the large amount of pressure that’s applied to ensure the weld is secured. Like all other kinds of friction welding the strength of the joint is dependant on a number of factors such as pressure, period of the friction motion and duration of the weld. As it turns out friction welding of wood is actually an active area of research with lots of investigation into how to create the strongest joints.

Even cooler is the fact that some researchers have developed a technique that allows the welds to be done with no fibres being expelled out the sides. This means that there was no charring of the interface medium, enabling the resulting weld to be even stronger and much more resistant to intrusion by moisture. Whilst you’re not going to see a sub built of friction welded wood any time soon it does mean that, potentially, your house could be built without the use of fasteners or joiners and the first rain that came through wouldn’t make it all come unstuck.

Don’t think you can just go off and rub two pieces of wood together though, the frequency required to fuse the wood was on the order of 150Hz and a pressure of 1.9MPa, far beyond the capabilities of any human to produce. Still it’s not unthinkable that a power tool could be made to do it, although I lack the mechanical engineering experience to figure out how that would be done. I’m sure someone will figure that out though and I can’t wait to see what kind of structures can be made using friction welding techniques.

The Sun’s Serenity.

Our sun is an incredibly violent thing, smashing atoms together at an incredible rate that results in the outpouring of vast torrents of energy into our solar system. Yet from certain perspectives it takes on a serene appearance, its surface ebbing and flowing as particles trace out some of its vast magnetic field. Indeed that’s exactly what the following video shows: a gorgeous composition of imagery taken from NASA’s Solar Dynamics Observatory. Whilst not all of us have the luxury of a 4K screen it’s still quite breathtaking to behold and definitely worth at least a few minutes of your time.

SDO has been in orbit for 5 years now keeping an almost unbroken eye on our parent star. Its primary mission is to better understand the relationship that our earth and the sun have, especially those which have a direct impact on daily life. To achieve this SDO is observing the sun in multiple wavelengths all at once (shown as different colours in this video) and on a much smaller timescale than previous craft have attempted. This has led to insights into how the sun generates its magnetic field, what it looks like and how the complex fusion processes influence the sun’s varying outputs like solar wind, energetic particles and variations in its solar output. Those images aren’t just rich with scientific data however as they showcase the sun’s incredible beauty.

So, how’s the serenity? 😉

The Incredibly Complexity of Ant’s Antenna Cleaning.

We’ve all watched ants go about their business. They scurry along the ground or up walls, busying themselves with transporting all sorts of things back to their nest. Every so often though you’ll see them stop and begin cleaning themselves, rubbing their antennae vigorously for quite a while before they continue the task at hand. If you’re like me you thought that was a pretty simple thing, all animals need to keep themselves clean, but that simple process belies some incredible evolutionary adaptations that ants have. Indeed as the video shows these adaptations are so advanced that replicating them could provide some benefits for the semiconductor industry.

This translation of evolutionary adaptations being translated to technical applications is called biomimicry and has played a pivotal role in technological development for quite a while. Some of the most notable examples include the development of velcro which takes inspiration from the hooks present on burs which allowed them to attach to an animal’s fur in order to spread their seed over a greater distance. The combo that the ants have could prove useful for semiconductors which are very susceptible to contamination, with other potential applications at the micro scale that require similar filtration and cleaning.

Isn’t it amazing what millions of years of evolution can come up with!

The Solar System to Scale.

Scale is something that’s hard to comprehend when it comes to celestial sized objects. The sheer vastness of space is so far beyond anything that we see in our everyday lives that it becomes incomprehensible. Yet in such scale I find perspective and understanding, knowing that the universe is far greater than anything going on in just one of its countless planets. To really grasp that scale though you have to experience it; to understand that even in our cosmic backyard the breadth of space is astounding. That’s just what the following video does:

Absolutely beautiful.

3D Printed Model Jet Engine Demonstrates Reverse Thrust.

Have you ever wondered how planes manage to slow down so fast? It’s not that they have amazing brakes, although they do have some of the most impressive disc brakes you’ll ever see, no most of the work is done by the very thing that launches them into the sky: the engines. The way they achieve this is called thrust reversal and, as the name would imply, it redirects the thrust that the engine is generating in the opposite direction, slowing the craft down rather than accelerating it. The way modern aircraft achieve this is wide and varied but one of the most common ways is demonstrated perfectly with this amazing 3D printed scale model:

The engine that the model is based off of is a General Electric GEnx-1B, an engine that’s found in the revamped Boeing 747-8 as well as Boeing’s new flagship plane the 787. Whilst this model lacks the complicated turbofan internals that its bigger brothers have (replaced by a much simpler electric motor) the rest of it is to specification, including the noise reducing chevrons at the rear and, most importantly, the thrust reversal mechanism. What’s most impressive to me is that the whole thing was printed on your run of the mill extruder based 3D printer. If you’re interested in more details about the engine itself there’s an incredible amount of detail over in the forum where the creator first posted it.

As you can see from the video when the nacelle (the jet engine’s cover) slides back a series of fins pop up, blocking the fan’s output from exiting out of the rear of the engine. At the same time a void opens up allowing the thrust to exit out towards the front of the engine. This essentially changes the engine from pulling the craft through the air to pushing back against it, reducing the aircraft’s speed. For all modern aircraft, even ones that use a turboprop rather than a fan, this is how they reduce their speed once they’ve touched down.

Many of us have likely seen jet engines doing exactly that but the view that this model gives us of the engine’s internals is just spectacular. It’s one of those things that you don’t often think about when you’re flying but without systems like these there’s no way we’d be flying craft as big as the ones we have today.

Lexus’ Hoverboard is Deceptive Wankery.

There are some technological ideas that captivate the public consciousness, our want for them to exist outstripping any ideas of practicality or usability. Chief among such ideas is the flying car, the seemingly amazing idea which, should it ever become mainstream, poses far more issues than it could ever solve. Still there have been numerous companies who have worked towards making that idea a reality with nearly all of them meeting the same fate. A close second (or third, if you’re more a jetpack fan) is the hoverboard, a device that replicates the functionality of a skateboard without the wheels. Our collective desire for something like that is what results in videos like the following and, honestly, they give me the shits:

Anyone who’s followed technology like this knows that a hoverboard, one that can glide over any surface, simply isn’t possible with our current understanding of physics and level of technological advancement. However if you grab a couple powerful electromagnets and put them over a metallic surface you can make yourself a decent simulacrum of what a hoverboard might be, it just can’t leave that surface. Indeed there’s been a few of these kinds of prototypes in the past and, whilst they’re cool and everything, they’re not much more than a demonstration of what a magnet can do.

This is where Lexus comes in with their utterly deceptive bullshit.

Just over a month ago Lexus put out this site showing a sleek looking board that was billowing smoke out its sides, serenely hovering a few inches above the ground. The media went ballistic, seemingly forgetting about what would be required to make something of this nature and the several implementations that came before it. Worst still the demonstration videos appeared to show the hoverboard working on regular surfaces, just like the ones in the movies that captured everyone’s imaginations. Like all good publicity stunts however the reality is far from what the pictures might tell and I lay the blame squarely at Lexus for being coy about the details.

You see the Lexus hoverboard is no different to the others that came before it, it still uses magnets and requires a special surface in order to work. Lexus built that entire set just to demonstrate the hoverboard and was mum about the details because they knew no one would care if they knew the truth. Instead they kept everything secret, making many people believe that they had created something new when in reality they hadn’t, all they did was put a larger marketing budget behind it.

Maybe I’ve just become an old cynic who hates fun but, honestly, I really got the shits with Lexus and the wider public’s reaction to this malarkey. Sure it looks cool, what with the slick design and mist cascading over the sides, but that’s about where it ends. Everything past that is Lexus engaging in deceptive marketing tactics to make us think it’s more than it is rather than being straight up about what they did. Of course they likely don’t care about what a ranty blogger on a dark corner of the Internet thinks, especially since he’s mentioned their brand name 10 times in one post, but I felt the need to say my peace, even if it wouldn’t change anything.