Hacker Newsnew | past | comments | ask | show | jobs | submit | taylorportman's commentslogin

Often these dongles were just a single resistor 'circuit'

Like a warded lock. It only keeps honest people honest — and proves intent to not pay.

The mirror coating timelapse video is pretty awesome https://www.youtube.com/watch?v=Gg9UPS7ndRA


Why is the substrate glass? Lack of reactivity? Ability to remove imperfections? As a layman with almost zero knowledge of telescope construction, I feel like a heavy amorphous solid would not be my first choice for the base layer underneath the reflective/mirror coating.


Its not your normal soda-lime glass, its more of a glass-ceramic material that have very low coefficient of thermal expansion, something like zerodur: https://en.m.wikipedia.org/wiki/Zerodur , which means it can keep its shape and focus even under varying temperature

Interesting demo by Huygens Optics: https://youtu.be/qi8jmEbWsxU?si=rj0I3k-l74Xhg7vC


I think while the smaller mirror here is Zerodur, the larger one is just borosilicate,

https://astro.arizona.edu/news/rubin-observatory-achieves-an...


That would be an odd choice.

A large glass mirror once cracked because they "only" allowed one year for it to cool.

The second one was allotted three years.


He did 'do it', and saved us all the 10-15minutes it took.


Technical debt, so hot right now.


I mean that choice of framework has very little to do with technical debt. So you claim something like this to create attention.


If you need a 100 meter antenna - could one be approximated using multiple drones in a coordinated 100 meter parabolic trajectory?


Yes, if you can coordinate and hold their position to ~1/10th of the wavelength (gets challenging above a few GHz), and synchronize their transmitters/receivers with ps accuracy (feasible if there's no GPS interference). And somehow you're exchanging the raw signal components amongst all the platforms.

The parabolic distribution is not at all needed in this case, you would just adjust the phase at each unit based on the distribution you have.

It is a thing that's considered, mostly for very low frequencies (1-100MHz) where all the above challenges are vastly simplified, and also large antennas (potentially km) are needed for any kind of directionality.


No need to hold their position that accurately, just need to know, ideally in real-time.


At 6Ghz, 5cm wavelength, 1/10 would be 5mm. I think that might be a bit under regular RTK accuracy.

But at lower frequencies, maybe. Or you can do several passes with the same drone and process later :D


If the drones use e.g. laser rangefinders to measure the distance to 2-3 known reflectors, and maybe to each other, with sub-mm accuracy, that may be enough.

Deploying an antenna that's effectively 50 or 100 m wide by lifting 10-20 drones, after some simple ground preparations, could be invaluable in many scenarios, especially for the military, of course.


The same technique as he uses here for synchronizing the receivers would work. Common reception and triangulation of a strong local beacon would enable positioning at much better than GNSS precision, both because of the SNR advantage itself and because you'd have more options for dealing with carrier phase ambiguity.


Does UWB provide enough accuracy to be useful or would you need something else?


Your ambivalence contributes little to the conversation.


It represents the same position of mediocre acceptance that many espresso affectionadors will arrrive at after spending many months/years mucking about with expensive kit.

It’s the natural progression of most hobbies


Whereas I appreciated the unexpected spice, only to quickly be reminded by your comment that, yes, this is HackerNews.


Wait till you see my cookbook, "1-minute Meal Replacement Powders", the perfect complement to my self-help/self-sabotage title, "Better Living Through Lower Standards".

YOLO, and no one gets it right on the first try anyway...


Are you offering shares in your venture? I’d be mildly interested in investing on the expectation that I’d see returns that are slightly worse than inflation.

Not that interested though, so whatever.


You may be interested in my philosophy on uptime: nine nines is hard, how about eight eights.


I was wondering too, if maybe under the right conditions, humidity sensors could trigger polarization of the glass surface followed by opposite polarization could potentially rid the surface of at least some of the dust. Some ionizing devices even produce a 'wind' of sorts.


I wonder if there is a common substance that could be scanned for historical interactions - like some salt flats.. that might preserve, like film, a history of energetic anomalies.


One such is a Miyake event. https://en.wikipedia.org/wiki/Miyake_event

> an observed sharp enhancement of the production of cosmogenic isotopes by cosmic rays. It can be marked by a spike in the concentration of radioactive carbon isotope 14C in tree rings, as well as 10Be and 36Cl in ice cores, which are all independently dated.

Wood and ice are pretty common. :)

I don't know if there are other examples.


Menuet & Kolibri are still actively maintained though.


Eventually medical science is going to arrive at methods that have potential to cure/create disease, novel organisms, synthetic organisms, etc. I don't think we want these methods pursued in a geopolitical vacuum either - like an arms race. It is inevitable and the only way to improve our collective chances of survival will be to co develop building codes, quarantine strategy, and agile attitudes to respond in time.


Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: