Jiffy 3D Aluminum

HacDC community member Julia Longtin and collaborator, Mason Mooney, have been developing a fascinating method to 3D print aluminum via a lost PLA method. It is remarkable for its use of commonly available consumer products such as microwave ovens, sugar, and hair spray. They have posted it to Hackaday and we are sure you'd agree that it deserves as many up votes as possible! Please spread the word if you agree!

Finished aluminum part, after removing from mold

“Our system uses consumer microwave units to perform burn-out of PLA from molds, and a second microwave to liquify aluminium, to be poured into the mold. 3d printer inspired mechanics will move the aluminium from the microwave, into the target mold under human control across the network, so that there is no risk to the person operating the machine.

“Lost PLA is usually dangerous, and time consuming. with this, we can go from [PLA] printed part to cast aluminium part in 3 hours!”

UPDATE (8/20/14): Julia et al. made the front of Hackaday!

Time Travel: Resolving the Grandfather Paradox – Experimentally

Mutant Fish

The mere fact that people are doing experiments which explore time travel, and publishing their results in respected peer-reviewed journals is pretty damn amazing. The article, https://www.physorg.com/news/2011-03-grandfather-paradox.html talks about a series of experiments that are being performed by folks at MIT and elsewhere to see exactly what is preventing the grandfather paradox from occurring during time travel.

“Ah!” You might say – just make time travel against the laws of physics, and you can avoid the whole issue. Unfortunately, or perhaps fortunately, travel on the so-called “closed timelike curves,” or “CTCs” is allowed by general relativity. The problem has been how to resolve issues like the case when you show a mathematician a proof from the future and she proceeds to publish _that_proof_. The question about where that proof came from is left as an exercise for the reader. For all the details, you can read the complete paper at Physics Review Letters: https://prl.aps.org/abstract/PRL/v106/i4/e040403