Leonardo Da Vinci’s Visualization Of Gravity As A Form Of Acceleration

Although we take a lot of scientific knowledge for granted today, each of the basics – whether it be about light, gravity, mass or the shape of the Earth – had to be theorized and experimentally verified. In the case of gravity, as far back as around 500 BCE the Ionian Greek philosopher Heraclitus theorized on the balance created by what we came to call ‘gravity’. Later, the Greek philosopher Aristotle coined his own postulations and Greek physicist Archimedes did research that led him to discover the center of mass. Centuries later, the Roman engineer and architect Vitruvius argued for the concept of specific gravity rather than mass alone.

Da Vinci’s sketch and the Caltech experiment replicating it.

Although scientific pursuits in this area ground to a halt in Europe during medieval times, the Renaissance saw a renewed interest in the topic, with newly published research performed on Leonardo da Vinci‘s notes showing that he appears to – unsurprisingly – have also created a number of experiments aimed at determining the properties of gravity. One of the major limitations of the 15th century was that many of the basic scientific tools we have come to rely on since the 19th century such as accurate clocks, along with many other products of advanced alloys and metallurgy simply did not exist. Da Vinci’s experiment in this context is nothing if not ingenious in its simplicity.

By the time of the European Renaissance, the Aristotelian concept of gravity as solely a factor of an object’s mass was dismissed by many in favor of a model that saw the motion of an object affected by its velocity and mass, also influenced by works published by Persian scholars. When Da Vinci set up his experiment, he focused specifically on the acceleration of the falling objects by pouring a large number of granules or possibly water droplets from a pitcher which was being pulled along a straight path. He theorized that if the pitcher was being accelerated at the same rate as the objects are accelerating due to gravity, it’d create a isosceles right triangle.

When the researchers ran his experiment and compared Da Vinci’s notes on the results, they realized that although he had made a mistake in his model, at the small scale this would not have affected the results, making it valid and an early precursor to what later be published by Isaac Newton in the 17th century.

Tactile Feedback In VR, No Cumbersome Gloves Or Motors Required

This clever research from the University of Chicago’s Human Computer Integration Lab demonstrates a fascinating way to let users “feel” objects in VR, without anything getting in the way of using one’s hands and fingers normally. Certainly, the picture here shows hands with a device attached to them, but look closely and you’ll see that it’s on the back of the hand only.

There’s hardware attached to the hands, yes, but only to the backs. Hands and fingers can be used entirely normally while receiving tactile feedback.

The unique device consists of a control box, wires, and some electrodes attached to different spots on the back of the hand and fingers. Carefully modulated electrical signals create tactile sensations on the front, despite originating from electrodes on the back. While this has clear applications for VR, the team thinks the concept could also have applications in rehabilitation, or prosthetics.

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VCF East 2023: Adrian Black On Keeping Retro Alive

While roaming the halls of Vintage Computer Festival East 2023, we ran into [Adrian Black], who was eager to talk about the importance of classic computing in his own life and how his experience hosting the YouTube channel Adrian’s Digital Basement has impacted him these last few years.

On his channel, [Adrian] spends most of his time repairing vintage systems or exploring little-known aspects of hardware from the early days of desktop computing. His exploits have brought him to the pages of Hackaday in the past, most recently just last month, when we covered his work to add an RGB interface to a mid-1990s Sony Trinitron CRT display. But in talking to him, you quickly realize he’d be working on the very same projects whether the camera was rolling or not. He’s not out to game the YouTube algorithm; he’s just having a good time in the basement poking around with the sort of old gear that at one time would have been completely out of reach.

Exploring a rare SWTPC 6800 computer

In fact, it’s this sense of nostalgia that [Adrian] believes is responsible not just for the growing popularity of his channel but for the retrocomputing community as a whole. For many who grew up with these machines, they were far too expensive or complex to ever crack open (literally and figuratively) when they were new. Now, decades later, people like himself finally find themselves able to buy and enjoy these once-coveted objects.

Critically, they now also have the skills to do them justice, not to mention access to a worldwide community of like-minded folks who are still producing hardware and software that can be used with these classic machines. For those of a certain age, it’s literally a dream come true.

[Adrian] was just one of the retro aficionados we got a chance to talk to during VCF East 2023. We already brought you the chat we had with [Andy Geppert] about magnetic core memory and his Core64 device, but there’s plenty more to come. Stay tuned.

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Printed Gas Can Accessories Make Refueling A Little Neater

No matter what your position is on internal combustion engines, it’s pretty safe to assume everyone is on the same page regarding wasting fossil fuels: it’s a bad thing. And nothing is as frustrating as spilling even a drop of the precious stuff before you even get a chance to burn it.

Unfortunately, the design of gas cans, at least here in North America, seems to have been optimized for fuel spillage. Not willing to settle for that, [avishekcode] came up with a 3D-printable replacement nozzle that should make dispensing gas a bit neater. It’s designed to fit one of the more popular brands of gasoline jugs available here in the States, and rather than the complicated stock nozzle, which includes a spring-operated interlock that has to be physically forced into a filler neck to open the valve, the replacement is just a slender tube with a built-in air vent. The vent keeps a vacuum from forming in the gas can and makes for a smooth, easy-to-control flow of gas and less spillage. The video below shows it in action.

The obvious issue here is chemical compatibility, since gasoline doesn’t work and play well with all plastics. [avishekcode] reports that both PLA and PETG versions of the nozzle have performed well for up to two years before cracking enough to need replacement. And then, of course, the solution is just to print another one. There may be legal issues, too — some localities have ordinances regarding gasoline storage and dispensing, so it’s best to check before you print.

Of course, one way to avoid the problems associated with storing and dispensing gasoline is to convert to electric power tools and vehicles. But as we’ve seen, that presents other problems.

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Hackaday Prize 2023: The Assistive Tech Challenge Starts Now

We’d all love to change the world and make it a better place, but let’s be honest…that’s a pretty tall order. Even the best of ideas, implemented perfectly, can only do so much globally. But that doesn’t mean the individual can’t make a difference — you just need to think on a different scale. If improving everyone’s life is a bit out of reach, why not settle for a smaller group? Or perhaps even just one person?

That’s precisely what we’re looking for in the Assistive Tech Challenge of the 2023 Hackaday Prize. In this Challenge, we’re asking the community to come up with ideas to help those with disabilities live fuller and more comfortable lives.

Whether you help develop an improved prosthesis that could benefit thousands, or design a bespoke communication device that gives a voice to just a single individual, it’s hard to imagine a more noble way to put your skills and knowledge to use.

Looking to lend a hand? You’ve got from now until May 30th to enter your Assistive Tech project. It doesn’t matter what kind of impairment it focuses on — so long as it helps somebody work, learn, or play, it’s fair game to us.

The ten finalists for this Challenge will be announced around June 12th, but you’ll have to wait until Hackaday Supercon in November to find out which projects take home their share of the more than $100,000 in cash prizes graciously provided by sponsors Digi-Key and SupplyFrame.

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Smoke Some Weeds: Lasers Could Make Herbicide Obsolete

We’ve all tangled with unwelcome plant life at one point or another. Whether crabgrass infested your lawn, or you were put on weeding duty in your grandfather’s rose patch, you’ll know they’re a pain to remove, and a pain to prevent. For farmers, just imagine the same problem, but scaled up to cover thousands of acres.

Dealing with weeds typically involves harsh chemicals or excessive manual labor. Lasers could prove to be a new tool in the fight against this scourge, however, as covered by the BBC.

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Nuke Your Own Uranium Glass Castings In The Microwave

Fair warning: if you’re going to try to mold uranium glass in a microwave kiln, you might want to not later use the oven for preparing food. Just a thought.

A little spicy…

Granted, uranium glass isn’t as dangerous as it might sound. Especially considering its creepy green glow, which almost seems to be somehow self-powered. The uranium glass used by [gigabecquerel] for this project is only about 1% U3O8, and isn’t really that radioactive. But radioactive or not, melting glass inside a microwave can be problematic, and appropriate precautions should be taken. This would include making the raw material for the project, called frit, which was accomplished by smacking a few bits of uranium glass with a hammer. We’d recommend a respirator and some good ventilation for this step.

The powdered uranium glass then goes into a graphite-coated plaster mold, which was made from a silicone mold, which in turn came from a 3D print. The charged mold then goes into a microwave kiln, which is essentially an insulating chamber that contains a silicon carbide crucible inside a standard microwave oven. Although it seems like [gigabecquerel] used a commercially available kiln, we recently saw a DIY metal-melting microwave forge that would probably do the trick.

The actual casting process is pretty simple — it’s really just ten minutes in the microwave on high until the frit gets hot enough to liquefy and flow into the mold. The results were pretty good; the glass medallion picked up the detail in the mold, but also the crack that developed in the plaster. [gigabecquerel] thinks that a mold milled from solid graphite would work better, but he doesn’t have the facilities for that. If anyone tries this out, we’d love to hear about it.