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🎓 Dr. Freemo :jpf: 🇳🇱

Some of the physics students I tutor recently asked me to explain the Casimir Effect in simple conceptual terms, so here it is...

The Casimir Effect can be noticed if you take two plates separated by a very small distance in a vacuum; there will be a mysterious force that causes the plates to be attracted to each other.

The cause of this effect is analogous and similar to having two plates in a medium, like water; If you apply sound waves to the water with a wavelength greater than the distance of the separation of the plates you will notice the plates will attract. This is because the waves are too big to enter the space between the plates and as such they exert a force on the outside faces of the plates and none on the inside faces, causing them to attract.

However with the Casimir Effect the plates are in a vacuum, and the waves come from quantum fluctuations rather than traditional mechanical waves. As we know from quantum mechanics everything can be represented as waves. We also know that at very small dimensions we witness a "quantum foam", essentially particles and energy constantly flashing in and out of existence. These particles and energy are essentially the source of the waves in a vacuum. If the plates are sufficiently close then only particles and energy of sufficiently small wavelength will occur between the plates, while larger wavelengths would be free to form in the space outside the plates. As such a similar effect as our water example occurs where there are more waves to exert a force on the outside faces of the plates than on the inside faces. As such the two plates are again attracted to each other.

en.wikipedia.org/wiki/File:Wat

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🎓 Dr. Freemo :jpf: 🇳🇱 boosted
ComPhys

@freemo I used the AD8302 recently as part of an analogue phase detection system for a linear accelerator. I hadn't thought about how they could be used in a VNA.

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🎓 Dr. Freemo :jpf: 🇳🇱 boosted
cool_boy_mew
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🎓 Dr. Freemo :jpf: 🇳🇱 boosted
🎓 Dr. Freemo :jpf: 🇳🇱

I think I may have finally finished the Version 2 Schematic of my "Ridiculously Over Engineered SWR meter" or ROES for short.

Its basically an Arduino based SWR meter with an LCD display (not depicted here as that is a seperate shield). But it provides all the functions of a Vector Network Analyzer (VNA) and goes way beyond your typical SWR meter. The only thing it doesn't have that a VNA would have is a function generator, as it relies on the transmitter to do that.

Generally you'd hook a directional coupler into your feedline (I'll be providing that as a seperate kit) and then tie the forward and reflected ports into this shield.

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🎓 Dr. Freemo :jpf: 🇳🇱 boosted
🎓 Dr. Freemo :jpf: 🇳🇱

@SecondJon Aww thanks you've been a pleasure to have and no one has ever reported you, which is impressive in the fediverse. So you're doing something right.

Its funny the second a new member comes around (as I'm dealing with this now) who is even remotely right leaning, or even just criticizes the left from time to time, they get blasted with reports about being alt-right this or that, usually on the most respectful and innocuous comments.. There are so many instances that probably ban for that that it comes across as effective. We have our rules for a reason, to protect respectful but unpopular opinions.

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🎓 Dr. Freemo :jpf: 🇳🇱 boosted
SecondJon

Wow. Two years here on , nearly 2k toots. Always happy to be here @freemo and grateful for this place.

I remember when I decided to try mastodon and signed up on more than one instance to find the rules written in a way that could be used to easily target users restrictively and found users very unfriendly and rude to others with the slightest difference of opinion. Not on qoto. Thanks to everyone here for making this a good place to be.

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🎓 Dr. Freemo :jpf: 🇳🇱 boosted
arXiv Quantitative Biology

Darwinian Evolution of Taste. (arXiv:2008.12984v1 [q-bio.OT]) arxiv.org/abs/2008.12984

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🎓 Dr. Freemo :jpf: 🇳🇱

I think I may have finally finished the Version 2 Schematic of my "Ridiculously Over Engineered SWR meter" or ROES for short.

Its basically an Arduino based SWR meter with an LCD display (not depicted here as that is a seperate shield). But it provides all the functions of a Vector Network Analyzer (VNA) and goes way beyond your typical SWR meter. The only thing it doesn't have that a VNA would have is a function generator, as it relies on the transmitter to do that.

Generally you'd hook a directional coupler into your feedline (I'll be providing that as a seperate kit) and then tie the forward and reflected ports into this shield.

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🎓 Dr. Freemo :jpf: 🇳🇱

Same circuit simulator I showed earlier, this time demonstrating a wideband phase shift circuit I'm working on.

falstad.com/circuit/circuitjs.

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🎓 Dr. Freemo :jpf: 🇳🇱

A neat circuit simulation I worked on a while back that was intended to provide automatic RF gain control.

In other words regardless of how strong or weak the input signal is the circuit would either attenuate or amplify the signal to bring it to ~ 3V. The idea was to be able to use it to analyze signals with a wide range of input voltages on a 3.3V chip. It was going to be part of a frequency counter but I created a simpler design for that in the end.

Either way check it out and play with it even if the circuit doesnt interest you as this web-based circuit simulator is pretty cool if your a beginner or just want to mess around with a circuit idea.

falstad.com/circuit/circuitjs.

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🎓 Dr. Freemo :jpf: 🇳🇱

Man designing the shielding, and more specifically finding the correct part of just the right size that is affordable, for an electronics project is a bigger pain in the ass than I would have figured!

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🎓 Dr. Freemo :jpf: 🇳🇱 boosted
stux⚡️

Sweet dreams!

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🎓 Dr. Freemo :jpf: 🇳🇱 boosted
Demosthenes

@freemo
I agree. It was very bad choice of language on my part, and I appreciate it being pointed out to me.
@louiscouture @Tel

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🎓 Dr. Freemo :jpf: 🇳🇱 boosted
Louis Couture :quebec: 🏳️‍🌈

@Demosthenes @Tel sexual orientation has nothing to do with how masculine you are.

There are really masculine gays while there can be really feminine straight men. Also if it wasn’t the case, there wouldn’t be lesbian trans women.

You can dress all the way you want, but when you say things like : I don’t want to be perceived as gay, you perpetuate negative stereotypes about LGBT people which only ends up hurting them.

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🎓 Dr. Freemo :jpf: 🇳🇱 boosted
Demosthenes

What Mastodon client(s) do you all use? I use Fedilab and it works well, but I always like trying different things.

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🎓 Dr. Freemo :jpf: 🇳🇱 boosted
Chris :freebsd:

Earth’s nearest supergiant is cooling down at the end of its life 

Scientists now believe the dimming of Betelgeuse was caused by a giant sunspot ...

manchester.ac.uk/discover/news

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🎓 Dr. Freemo :jpf: 🇳🇱 boosted
Chris :freebsd:

quantamagazine.org/the-hidden-

and the , how magnetism could explain the Hubble tension.

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🎓 Dr. Freemo :jpf: 🇳🇱 boosted
Chris :freebsd:

Big Bounce Simulations Challenge the Big Bang | Quanta Magazine 

Recent computational gravity simulations show that cyclic universes can have the same features as inflationary models.

quantamagazine.org/big-bounce-

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🎓 Dr. Freemo :jpf: 🇳🇱

A slightly delayed / I know, but I also don't want to skip this one as we have a lot of new cool people

===== New =====

@louiscouture - A new user from Quebec, his profile reads: I like coding, technology and taking long walks, photography, politics and science. 8values says I’m libertarian socialist but I am just confused and only want a better world for all of us. Do not talk to me about inches and feet unless it’s body parts because I do not understand what it is.

@compass_straight_edge - His interests (that I know of) seem to be and

@svmihar - A gamer and a coder, does some .

@EVoCeO From his profile: Hi, new to decentralized social media and social media in general. I chose Mastodon because if its uncensored nature and chose qoto because of its philosophy. Such a fresh take on social media I'm excited to try it out.

@Demosthenes - Also brand new, but has jumped right in and been pretty active since he signed up.

@ml - Seems like an Open-source / user. He is brand new but gonna keep an eye on him for future posts.

===== Old=====

@soundofsun - From her profile: 𝖐𝖊𝖊𝖓 𝖔𝖓 𝖆𝖓𝖆𝖑𝖞𝖟𝖎𝖓𝖌 𝖙𝖍𝖊 𝖘𝖍𝖚𝖉𝖉𝖊𝖗 // 𝖑𝖞𝖎𝖓𝖌 𝖉𝖔𝖜𝖓 𝖎𝖓 𝖙𝖍𝖊 𝖉𝖆𝖗𝖐 𝖙𝖔 𝖉𝖗𝖊𝖆𝖒 // 𝖆 𝖗𝖔𝖈𝖐𝖆𝖇𝖎𝖑𝖑𝖞 𝖗𝖎𝖉𝖊 𝖋𝖗𝖔𝖒 𝖙𝖍𝖊 𝖌𝖑𝖎𝖙𝖙𝖊𝖗 𝖙𝖔 𝖙𝖍𝖊 𝖌𝖑𝖔𝖔𝖒
☁️🌑🏔️🤍

@2ck - From his profile: A capable software engineer and aspirating (sic) cook

@JulianRott - Mostly posts interesting articles.

@zleap - Interested in , , Fediverse, Linux and free software.

@lupyuen - One of our embedded / IoT guys, seems to focus a lot on digital hardware and software. Lots of cool projects on his feed, he brands himself as "Techie and Educator in "

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🎓 Dr. Freemo :jpf: 🇳🇱 boosted
🌸🌹2ck 🌱🐇

I was only half-listening to a reading of , but I dialed in during the meeting with Corlis. It really connected with a lot in my personal history w.r.t. to , , and for the future
pugetsound.edu/files/resources

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