Ever since I can remember my joints have always been prone to popping and cracking. It was the worst when I was a child as I couldn’t really sneak around anywhere without my ankles loudly announcing my presence, thwarting my attempt at whatever shenanigans I was up to. Soon after I discovered the joy of cracking my knuckles and most other joints in my body, much to the chagrin of those around me. However even though I was warned of health effects (which I’m pretty sure is bunk) I never looked up the actual mechanism behind the signature sound and honestly it’s actually quite interesting:
Interestingly though whilst cavitation in the synovial fluid is one of the better explanations for where the sound originates there’s still some other mechanisms which can cause similar audible effects. Rapid stretching of ligaments can also result in similar noises, usually due to tendons snapping from one position to another. Some sounds are also the result of less benign activities like tearing of intra-articular adhesions tearing, although that usually goes hand in hand with a not-so-minor injury to the joint.
There’s also been a little more investigation into the health effects of cracking your knuckles than what the video alludes to. A recent study of 215 patients in the age range of 50 to 89 showed that, regardless of how long a person had been cracking their knuckles, there was no relationship between cracking and osteoarthritis in those joints. Now this was a retrospective study (in terms of people telling the researchers of how much they cracked their knuckles) so there’s potential for biases to slip in there but they did use radiographs to determine if they had arthritis or not. There’s no studies around other joints however, although I’d wager that the mechanisms, and thus their effects, are very similar throughout the body.
And now if you’ll excuse me I’ll be off to disgust my wife by cracking every joint in my body
Ever since I first saw a 3D printer I wondered how long it’d be before they’d start scaling up in size. Now I’m not talking about incremental size improvements that we see every so often (like with the new Makerbot Z18), no I was wondering when we’d get industrial scale 3D printers that could construct large structures. The steps between your run of the mill desktop 3D printer and something of that magnitude isn’t a simple matter of scaling up the various components as many of the assumptions made at that size simply don’t apply when you get into large scale construction. It seems that day has finally come as Suzhou Yingchuang Science and Trade Development Co has developed a 3D printer capable of creating full size houses:
Details the makeup of the material used, as well as its structural properties, aren’t currently forthcoming however the company behind them claims that it’s about 5 times as hard as traditional building materials. They’re apparently using a few of these 3D printed buildings as offices for some of their employees so you’d figure they’re somewhat habitable although I’m sure they’re in a much more finished state than the ones shown above. Still for a first generation product they seem pretty good and if the company’s claims hold up then they’d become an attractive way to provide low cost housing to a lot of people.
What I’d really be interested to see is how the cost and materials used compares to that of traditional construction. It’s a well known fact that building new housing is an incredibly inefficient process with a lot of materials wasted in during construction. Methods like this provide a great opportunity to reduce the amount of waste generated as there’s no excess material left over once construction has completed. Further refinement of the process could also ensure that post-construction work, like cabling and wiring, are also done in a much more efficient manner.
I’m interested to see how inventive they can get with this as there’s potentially a world of new housing designs out there to exploited using this new method. That will likely be a long time coming however as not everyone will have access to one of these things to fiddle around with but I’m sure just the possibility of a printer of this magnitude has a few people thinking about it already.
Liquid nitrogen is a scientific staple that I’m sure we’re pretty much all familiar with. It’s a great demonstration of how the melting and boiling points can vary wildly and, of course, everyone loves shattering a frozen banana or two. However seeing the other stages of elemental gases is typically impossible as getting the required temperature is beyond the reach of most high school science labs. However there is a trick that we can use to, in essence, trick nitrogen into forming a solid: reducing the pressure to a near vacuum. The results of doing so are just incredible with the nitrogen behaving in some really peculiar ways:
The initial stages of the nitrogen transitioning into a solid is pretty standard with the reduced pressure resulting in the superheated boiling, plunging the temperature of the remaining liquid. The initial freezing is also something many will be familiar with as it closely mimics what happens when water freezes (although lacking water’s peculiar property of expanding when freezing). The sudden, and rather explosive, crystalline formation after that however took me by surprise as I’ve never really seen anything of that nature before. The closest thing I could think of was the fracturing of a Prince Rupert’s Drop although the propagation of the nitrogen crystalline structure seems to be an order of magnitude or two slower than that.
What really got me about this video is that it wasn’t done by a science channel or vlogger, it’s done by a bunch of chefs. Liquid nitrogen has been used in various culinary activities for over a century, mostly due to its extreme low temperatures which form much smaller ice crystals in the food that it chills. It should come as no surprise really as there’s been a huge surge in the science behind cooking with the field of molecular gastronomy taking off in recent decades. It just goes to show that interesting science can be done almost anywhere you care to look and its applications are likely far more wide reaching than you’d first think.
I remember attending an exhibition about Leonardo Da Vinci a couple years ago and I was astounded by the complexity of some of the machines he created. It wasn’t just that he’d figured out these things where no one else had, more it was some of the things that he designed didn’t seem possible to me, at least with the technology he had available to him at the time. Ever since then I’ve had something of a fascination with mechanical structures, marvelling at creations that seem like they should be impossible. My favourite example of this is Theo Jansen’s Strandbeests, a new form of life that he has been striving to create for the better part of 25 years.
All of his designs are essentially tensegrity structures (I.E. all parts of the structure are under constant tension) arranged in such a way that when an outside force, in this case the wind at a beach, acts on them they’re able to walk. His initial designs only functioned when the wind was blowing however further designs, many of which you can see in the video, are able to store wind energy and then use it later through some rather clever mechanical engineering. Unfortunately I couldn’t find the best video which has Theo explaining how they work as that one also shows another Strandbeest he created that would avoid walking itself into the ocean (something which I’m still not sure I understand how it works completely).
The idea of creating a new form of life, even if it doesn’t meet the 7 rules for biological life, is a pretty exciting idea and one that’s found an unlikely form of replication: 3D printing. After many people made their own versions of his Strandbeests (I even printed a simple one off, although it broke multiple times during assembly) Theo has made the designs available through Shapeways, essentially giving the Strandbeests a way to procreate. Sure it’s not as elegant as what us biological entities have but the idea does have a cool sci fi bent to it that tickles me in all the right places.
Taken to its logical extreme I guess a Reprap that printed Strandbeests that assembled other Repraps would be the ultimate end goal, although that’s both exciting and horrifying at the same time.
Nature is full of patterns. For the most part these all have an organic feel to them, usually due to the soft curves or seeming randomness that’s inherent in it. Artificial things, like those constructed by man, have the opposite feel to them. Nothing highlights this more than when you compare the view of areas like sand dunes or dense forests against that of a city skyline. However every so often the lines between these two worlds seem to blur together with nature producing something that looks like it was forged by hand rather than by the natural processes of the world. One such example of this, and one I wasn’t aware of until I saw this video, was the creation of salt cubes in the Dead Sea:
There are many processes by which things like this can occur, Bismuth is a great example of this, taking on shapes that look down right otherworldly in origin, unlike many other minerals that take on much more organic shapes in their natural form. However in the case of Bismuth as well as these salt cubes there’s a simple explanation behind why they end up looking the way they do. For these salt cubes it comes down to the microscopic nature of the molecule, namely sodium chloride (table salt), manifesting itself in macro form.
The Dead Sea is a giant salt lake with an average salt content of around 35%. This is the perfect environment for salt crystals to form and since the solution is so saturated with salt the amount of impurities that make it into the crystal are relatively low. Thus the crystal structure grows in the most idyllic way which just so happens to be a square lattice. Whilst the cubes shown in the video are relatively small the limit on their size is no where near that, with square crystals able to grow up to several kilograms in size. If you were so inclined you could probably grow one several meters in size in a laboratory although the usefulness of such an activity would be highly questionable.
But you would have a giant cube of salt, no one could argue with that
Our spacecraft have reached nearly every corner of our solar system, from the barren sun baked world of Mercury to the (soon to be visited) frigid ice ball of Pluto. We’ve gazed at all of them from afar many times but there are precious few we have made even robotic footfall on, with only a single other heavenly body having human footprints on it. Still from those few where we’ve been able to punch through the atmosphere the scenery we’ve been greeted with has been both strangely familiar yet completely alien. Mars is most famous of these but few are aware of the descent video from the Huygens probe that it made on its way down to Titan’s surface:
Titan gets its thick orange atmosphere from its mostly nitrogen atmosphere being tainted by methane which is thought to be constantly refreshed by cryovolcanoes on its surface. Whilst the mountain ranges and valleys you see were formed in much the same way as they were here on Earth those lakes you see in between them aren’t water, but hydrocarbons. Indeed much of Titan’s surface is covered in what is essentially crude oil although making use of it for future missions would likely be more trouble than its worth.
Still it’s amazing to see worlds that are so like ours in one aspect yet completely foreign in so many other ways. This rare insight into what Titan looks like from on high is not only amazing to see but it has also provided invaluable insight into what Titan’s world actually is. I honestly could watch videos like this for hours as it’s just so mesmerizing to see the surface of worlds other than our own.
I loved Sonic the Hedgehog as a kid mostly because I could simply point myself in a single direction, mash the spin button and then watch as he flitted from one side of the screen to the other at breakneck speed. Whilst the physics of that particular game aren’t rooted in reality some of the principles were namely the forces of momentum, inertia and, most importantly centripetal force. That last one is the force responsible for keeping objects pinned down when going through loop the loops although you usually only see it in action on roller coasters or special stunt vehicles. I honestly didn’t think it’d be possible for a human to accomplish what our speedy blue friend did but it seems that, like many other things, I was wrong.
I was surprised to learn that the required speed to get around the loop safely was so low, well within the reach of anyone with a modicum of fitness. The real key here though is the technique as the way we humans generate force is vastly different to that of more traditional vehicles that can accomplish this feat. You see the force we generate isn’t in line with the surface we’re on, it’s at something of a 45 degree angle, which means that as you get to the higher parts of the loop you’ll actually be pushing yourself off it with your face heading directly towards the floor.
This becomes evident when you see the initial trial runs where he has to flip himself over at the peak of the loop. In the final, successful run you can see that when his foot hits the peak he doesn’t actually use that to generate any force. Instead he’s doing something like an upside down split kick with one foot travelling from one side of the loop to the other. It’s incredibly impressive to say the least and just goes to show that given enough practice, persistence and good old fashioned science the impossible can be achieved.
Most aircraft capable of Short Take -Offs and Landings (STOL) are usually small and nimble kinds of planes, usually being either designed for use in adverse conditions or, more famously, fighter jets that find their homes on aircraft carriers. The reasons for this are pretty simple: the larger you the make the aircraft the more power you require to shorten its take off and past a certain point regular old jet engines simply aren’t going to cut it any more. However there have been a few notable examples of large aircraft using JATO rockets to drastically shorten their take off profile and the most notable of which is the Blue Angels’ C-130 dubbed Fat Albert:
If you’ve ever seen one of these beasts take off in person (or even say, an Airbus A380 which is a monster by comparison) then you’ll know that they seem to take forever to get off the ground. Strapping 8 JATOs that produce 1000lbs of thrust to the back of them makes a C-130 look a fighter jet when its taking off, gaining altitude at a rate that just seems out of this world. Of course this then begs the question of why you’d want to do something like this as it’s not often that a C-130 or any of its brethren find themselves in a situation where taking off that quickly would be necessary.
In truth it isn’t as the missions that these large craft fly are typically built around their requirements for a long runway. There have been some notable examples though with the most recent being the Iranian Host Crisis that occurred over 30 years ago. After the failure of a first rescue attempt the Pentagon set about creating another mission in order to rescue the hostages. The previous mission failure was largely blamed on the use of a large number of heavy lift helicopters, many of which didn’t arrive in operational condition. The thinking was to replace those helicopters with a single C-130 that was modified to land in a nearby sports stadium for evacuation of the extraction teams and the hostages.
The mission was called Operation Credible Sport and was tasked with modifying 2 C-130 craft to be capable of landing in a tight space. They accomplished this by the use of no less than 30 JATO rockets: 8 facing backward (for take off), 8 facing forward (for breaking on landing), 8 pointed downwards (to slow the descent), 4 on the wings and 2 on the tail. The initial flight test showed that the newly modified C-130 was capable of performing the take-off in the required space however on landing the 8 downward facing rockets failed to fire and, in combination with one of the pilots accidentally triggering the breaking rockets early, the craft met its tragic demise thankfully without out injury to any of the crew.
Even Fat Albert doesn’t do JATO runs any more as a shortage of the required rocketry spelled an end to it in 2009. It’s a bit of a shame as it’s a pretty incredible display but considering it had no practical use whatsoever I can see why they discontinued it. Still the videos of it are impressive enough, at least for me anyway.
Everyone can relate to the frustration of having a drawer full of batteries that are in an unknown state of charge. For most people the only method they have to deduce whether they’re good or not is to try them out in a device, something that inevitably leads to frustration when your spares show up dead as well. The inclusion of battery testers on the batteries themselves (or in the packaging) seemed like a great idea however it never seemed to catch on presumably due to cost factors. Whilst geeks like myself might have a voltmeter handy to get accurate readings in an instant they’re not a ubiquitous device and an effective way of testing batteries still eludes most.
That is until they see this video:
Honestly when I saw this video I was pretty sceptical as the video, whilst highly informative, is anything but scientific. Instead of having 2 batteries from the same brand (and preferably from the same batch) for comparison the effect could be explained by differences in manufacturing between the two. I didn’t take the opportunity to test it myself however, even though I do have a drawer full of batteries that are all in unknown states, but after seeing this video parroted around various life hacking sites I figured that if it was total bunk someone would’ve called shenanigans. It seems that the video is accurate and the science behind why empty batteries bounce is very interesting.
It’s not, as many have speculated, related to a reduction in weight between a full battery and a discharged one. Batteries like this are a closed system, chemically speaking, so save for a few milligrams here and there due to handling or (more catastrophically) a breach in them batteries don’t change their weight. Instead it’s a quirk of the manufacturing process and the change in densities of the various materials inside the battery, all of which result in it becoming bouncy.
In a typical alkaline battery the chemical reaction that takes place to produce charge also results in the materials shrinking. The reason for this is that as the battery discharges oxygen molecules from the cathode (negative ) manganese oxide terminal migrate to the anode (positive) zinc anode, producing zinc oxide. When this occurs the total volume decreases as the oxygen atoms are able to pack themselves much tighter on the zinc oxide terminal than they can on the manganese oxide. This results in the internals shrinking somewhat and, as a consequence, tugs on the side of the pressure seal on the bottom of the battery. This causes it to bow outwards providing a spring like structure which results in the bounce when dropped.
Now I haven’t looked at a lot of batteries recently but I can image that some other designs might make this trick fail due to the design of the cathode terminal. This also means that the trick is probably unique to the cylinder style batteries (A, C, D, etc.) as whilst other types of batteries have similar chemical reactions their construction is vastly different. So I wouldn’t recommend dropping your car or latern batteries to try and test them out, lest you want to spend some time in the chemical burn ward and paying for a large chemical spill.
It doesn’t seem that long ago that Felix Baumgartner leapt from his balloon 39KMs above the Earth’s surface, breaking Joseph Kittinger’s long standing record. The whole journey took only minutes and the entire journey back down captivated millions of people who watched on with bated breath. Curiously though we only saw one perspective of it for a long time, that of the observation cameras chronicling Felix’s journey. Now we can have front row seats to what Felix himself saw on the way down, including the harrowing spin that threatened to end everything in tragedy.