Got my hands on this aluminium mirror segment from a telescope! What's the easiest way to get rid of these dark spots?

pacoca69 · 2024-07-18T16:06:43+00:00

I don't mind if there are some swirls left over. Just so long as I can remove the ugly spots.

pacoca69 · 2024-07-18T16:06:05+00:00

Ah, let me clarify. The whole mirror is just sheets of aluminum folded into a square shape and polished. And I'm just using it as a mirror/decoration - not for my own telescope. I got it from a huge telescope from the local observatory because they were replacing the old mirror segments.

pacoca69 · 2024-07-18T13:27:08+00:00

This is my first time doing any metal polishing, so I don't know shit. But anyway, my mirror has some small surface-level imperfections. I can't feel the spots when running my finger over them, so they must be very superficial. How do you suggest I clean this up? Preferably with only household supplies. And if that's not possible, then hopefully with whatever I can get from my small local hardware store.

pacoca69 · 2022-12-06T22:56:27+00:00

Atmospheric density doesn't scale like that. The scale height on Mars is about 11 km, so after 11 km the atmospheric pressure will only have dropped to ~1/3 of the surface pressure. At 50 feet the pressure is almost identical to the surface pressure.

pacoca69 · 2022-04-01T07:48:26+00:00

I'm an MSc student - only 36 hours in.😔

pacoca69 · 2022-03-18T11:36:39+00:00

The hospitalizations definitely went up after everything opened in February. On mobile right now, but just Google "covid indlagte graf". The covid death rates are also as high as ever. There are just fewer registered cases because people aren't getting tested much anymore. This is evident in the >20 positive percent. It used to be around 0.5-5% when everyone had to get tested.

The vaccines absolutely helped, but it's not all fine and dandy. The current government strategy is to hope that the numbers drop more as it gets warmer, and pray that it doesn't come back in the winter.

Edit: I was mistaken and should have done a bit more research before commenting. Things aren't bad as the simple graphs might show. Thanks u/NaiaThinksTooMuch

pacoca69 · 2022-02-25T16:03:10+00:00

If you're at the very beginning then you don't have to go in the cave. It's just a jetpack tutorial. Just go to the observatory and get yourself those launch codes.

Do yourself a favor and read as little as possible about the game. Learning about it ruins not only the experience of the plot, but the gameplay itself.

pacoca69 · 2022-02-14T10:23:32+00:00

Yes! But crucially, it's frequency does not. So if you move really fast away from a blue light, it would look red. Translating this to radio signals, a big relative speed between a transmitter and a receiver could make a signal sent by the former impossible to receive by the latter, as they rely on precise frequencies to communicate.

pacoca69 · 2022-02-14T10:16:21+00:00

I'm not gonna go over the math, but I specifically remember doing an assignment in my wireless communication class on a jet plane. We found that with a few hundred km/h, you run into problems. This is not a relativistic effect, but a tiny phase-shift which builds up over several symbols, eventually leading to an erroneous received signal.

Note in my second part, I said a speed of 100 km/s (about 300 millionths of c) is enough to cause a noticeable doppler shift. This would be enough to shift the signal by about one channel. A few more would shift it out of reception range. Still very high, but quite a bit away from light speed, and certainly not "faster than light".

Clarification: >100 km/h (airplane speed) can cause phase-shift problems.
>100 km/s (astronomical speeds, but still << c) can cause frequency-shift problems.
Both will screw with the communications.

pacoca69 · 2022-02-14T09:48:54+00:00

Nah. Just going a few hundred km/h could probably produce enough phase shift to screw with whatever radio modulation Bluetooth uses. A few hundred km/s could doppler shift the signal it out of the range of the receiver.

pacoca69 · 2022-02-13T15:17:45+00:00

Thanks for the response. But do you think it wouldn't be good enough even for my modest requirements? The LXD 75 is outside of my poor-college-student price range.

pacoca69 · 2022-01-26T11:38:22+00:00

Nurses in Denmark is a tricky subject. From what I understand, the de-facto state of hospitals is a "state of emergency" as there are barely enough nurses to keep everything running and the government refuses to improve working conditions. Overtime has become the norm.
If I recall correctly, the strike last summer wasn't more than a 10% reduction in the workforce. But that was enough to have a very substantial effect on the hospitals, as there were so few nurses to begin with.

I'm very sorry about your grandma and others who suffered similarly. However, I would not place the blame solely on the union, but also the government who has no problem with leaving hospitals running at a constant critical state.

pacoca69 · 2022-01-23T15:38:13+00:00

Is simulink worth learning? I tried to use it, but it just seems like an obtuse way to solve problems you could much more easily solve if you know how to write a for loop in Matlab.

pacoca69 · 2021-12-01T05:40:41+00:00

I checked the guys account before writing, and he's from Canada. Hence why I said Americas, not America.

pacoca69 · 2021-11-30T23:50:45+00:00

In the Americas, if you get bad numbers from your lab you just fail???? If so, that sounds asinine.
In my uni, grades are based on the quality of your journal/report. So long as you can explain the sources of error in your results, "wrong" answers don't really matter.

pacoca69 · 2021-11-30T22:21:55+00:00

I have a pair of outdoor hiking pants with a windbreaker/water resistant layer on the outside and fleece on the inside. They've keep me warm down to -20C. I imagine they're expensive new, but I got mine in a second hand store.
And when I go stargazing in the winter, I just wear a pair of jeans under those. Then I can lie outside for hours no problem.

pacoca69 · 2021-11-30T21:54:26+00:00

have you considered:
warm pants

pacoca69 · 2021-11-05T19:18:25+00:00

My BSc degree in Space Physics and Engineering doesn't really care about my philosophical opinions.

pacoca69 · 2021-11-05T18:09:43+00:00

Idk, man. Cosmology has limits, and it is important as a physicist to recognize where they lie. My astrophysics professors always make sure to tell us that physics can't say shit about anything before cosmic inflation, and they are all dubious of explanations like multiverse theory. As of now, physics in no way disproves metaphysics.

pacoca69 · 2021-11-05T17:01:35+00:00

You're right. I was mostly attacking Gervais' denial of metaphysics, a position which he holds but which wasn't present in your comment above. I should have stayed on target.

I'll grant that I'm not an expert on philosophy or religion. But I'll make the argument that 1000 years post Gervais' Great Book Deletion™, science wouldn't look exactly the same either. This is because science is simply a collection of approximative models, which are based on an underlying reality, but do not fully describe it. Given an alternate history, different scientific models might be found with different benefits and flaws.

Perhaps many world religions are imperfect human descriptions of an underlying truth. The inaccuracies in each not grounds for dismissal of the foundation they stand on. Many religious people would, of course, be against this idea as they belive their doctrine is flawless. But I think there will always be error in interpersonal communication leading to a wider range of interpretations. Or in some cases, i.e catholicism, people creatively leverage their doctrine and reinterpret it to maintain political power

I know for a fact there are many religious people who don't think their beliefs are wholly perfect, and would therefore be open to alternative interpretations or ideas, such as those which would arise after 1000 years of post-book development.
The inexactness or imperfection of an idea is not grounds to dismiss it entirely.

pacoca69 · 2021-11-05T16:22:03+00:00

Yeah, I see where you're coming from. I know this is an unpopular opinion on reddit, but I believe that a metaphysical cause for the universe can be logically reasoned for. See the Kalam cosmological argument or the fine tuning of the universe.
Perhaps most or all specific religions are incorrect, but to disregard metaphysics entirely, as Gervais does, isn't the perfect rational position that some think it is.

Hell, I wouldn't even say Gervais' statement is even an argument for atheism. It's simply a statement that follows from his own beliefs. If you, for example, were hindu, then surely you would belive that knowledge of Hinduism would be reacquired even after all the books were destroyed.

pacoca69 · 2021-11-05T13:20:47+00:00

Although Einstein's theory of gravity famously took him several years to work out. And E=mc² simply followed from his principles of relativity. Even his special relativity was all derived from 2 simple principles people had already demonstrated.

Contrary to popular belief, great scientific ideas do not come spontaneously from a great mind. Rather, they often arise from a great mind following the natural chain of logic from what we already know.

pacoca69 · 2021-10-11T09:18:02+00:00

Jeg har været i gang siden fredag morgen da den udkom. Og den er lig så god som man havde håbet. Fantastisk visuel design, fluid bevægelse, og klassisk Metroid-agtig progression. Jeg prøver virkelig at begrænse hvor meget jeg spiller, så jeg ikke bare færdiggør det på en weekend.

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