petschge

16 ms·

121.
by petschge 5y ago
That is because that package internally steps down that voltage. Any LED that produces light in the visible range will have a bandgap in the 1 to 2 Volt range. Feeding it a higher voltage than that would lead to disastrous current run away.
122.
by petschge 5y ago
24 bits precision would be possible with the Hastings approximation with 15 terms instead of 6 terms. A naive estimate would be that this requires 2.5 times as much work and could run at 6GB/s and take a little less than 5 cycles per e
123.
by petschge 5y ago
This is not to stop the people who can download from a torrent (without getting sued into oblivion for copyright violations) and know how to install an OS. It's to stop the other 99%. In some sense having an option for that 1% is a goo
124.
by petschge 5y ago
Now introducing Windows 12 Developer edition. Dark mode is enabled by default, Visual Studio comes preinstalled and it is $5000 a year. Cheap to a professional developer and keeps the masses from running their own code.
125.
by petschge 5y ago
The diffraction limit is a well supported theoretical limit that is caused by the wave nature of light. There is ways to get around it in the near field (up to a few ten wavelength away from the source). But in the far field you can not get
126.
by petschge 5y ago
May I refer you to https://www.edmundoptics.com/knowledge-center/application-no... ? Pay particular attention to the last paragraph: > Achieving a truly collimated beam where the divergence is 0 is not possible, but
127.
by petschge 5y ago
Yes, the so called diffraction limit. Has a lot of applications in optics.
128.
by petschge 5y ago
Sorry, but that is simply wrong. And yes, the inverse square law is strictly speaking only true for point sources. But it is an extremely good approximation once you are much further away than the size of the source (a distance ten times th
129.
by petschge 5y ago
Every finite width beam will have some divergence.
130.
by petschge 5y ago
Yeah in my field the general attitude is that Nature isn't all that great. I have heard the phrase "it was published in Nature but might still be right" more than once.
131.
by petschge 5y ago
I write papers too and hate finding a new way to say "my X is a Y that does Z". Especially if it is your tenth paper on the topic and you should even sound like the previous nine times. But about three sentences into the introduct
132.
by petschge 5y ago
If it only receives the near field, can I used that to subtract the near field from a close-by regular antenna? That should make it more immune to local influences and improve the SNR of a far away signal?
133.
by petschge 5y ago
The usual square law still applies. Of course if you are inside the beam cone, it look way brighter than an object of 10^35 W should look at the same distance, but if you move twice as far away, the brightness will still drop to one quarter
134.
Tilck – Tiny Linux-Compatible Kernel(github.com)
97 points by petschge 5y ago|7 comments
135.
by petschge 5y ago
> We choose to spend a ton of resources to prevent freeloading, even when the amount we spend to stop them is more than we actually lose to the freeloaders. Is it also more than what we would lose to freeloaders if we did nothing against
136.
by petschge 5y ago
I suggest you take a look at "Climate Impact of a Regional Nuclear Weapons Exchange: An Improved Assessment Based On Detailed Source Calculations" [1] or similar papers. Scientists have run nuclear bomb simulations (and these code
137.
by petschge 5y ago
I have heard astronomers estimating it at up to 30% of the observing time for existing optical telescopes. Note that this is the instrument class that has t to 20 times as many proposals as they can actually observe.
138.
by petschge 5y ago
Things rotating up is only true for stuff that is close to the Eastern or Western horizon. And yes different times of the year help a lot, but there is plenty of objects that are only visible a bit over the horizon at the best of times. Sou
139.
by petschge 5y ago
Because telescopes are so sensitive that the reflections of a bright satellite inside the optics bascially ruin all pixels in the frame. And there is so many satellite that all frames close to dusk/dawn are impacted. So you loose 1&#x2
140.
by petschge 5y ago
I agree that it is nice to have a native python library, but I'd argue that the gnuplot interface is much better designed than matplotlib.
141.
by petschge 5y ago
Not exponentially. That would be exp(v). But quadratically, which is faster than linear. I would really hope that at least here people would know that exponentially names a particular function and is not a synonym for "fast".
142.
by petschge 5y ago
Your math seems right at first glance. But keep in mind that it will only expel 25kg of working gas in those 14 hours. For a short trip to mars with a heavy rocket this kind of drive might not matter, but imagine a probe that can run this e
143.
by petschge 5y ago
Keep in mind that most of that comes from MHD simulation and MHD simulation are well known in the community to get details of reconnection quite wrong [1]. So until somebody has confirmed that with particle-in-cell simulations, hybrid simul
144.
by petschge 5y ago
Most if not all journals in my field allow you to upload the final accepted PDF that you have typeset in latex yourself to arxiv. We even put "accepted in $journal" and the DOI in the comment field. This includes all the changes y
145.
by petschge 5y ago
They would. But it is harder to get funding for three than it is to get funding for two...
146.
by petschge 5y ago
The A380 was a smooth ride, but oh so boring to fly on. But maybe I am weird for liking to fly on tiny things like ERJ135. In a A380 it's just 8 hours of noisy bus ride with way to many people.
147.
by petschge 5y ago
Come hike with me in the Rocky Mountains.
148.
by petschge 5y ago
10 years ago it was hard. These days the data connection over the cellular network is fast enough that you can just use VOIP and a provider like SIPgate that gives you access to the plain old telephony system. You can even move that number
149.
by petschge 5y ago
Enough providers in Europe are willing to sell you a second SIM card for a one time fee ($5 to $15) that shares the data budget with the sim card in your phone. Only trick is to configure which of the two SIM cards gets SMS for your number.
150.
by petschge 5y ago
Eventually? I have had Thinkpads with build-in cellular modem since at least 2004. (And I have used them under Linux. Fun memories of wvdial back in the days.) I have not had 5G in a laptop yet, but direct internet access over a cellular ne

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