“I built a fusion reactor in my bedroom – AMA” | Hacker News Reader

“I built a fusion reactor in my bedroom – AMA”

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434 pointslsllc127 comments

This kid is awesome but this particular comment really made me sad:

"Spending 3+ hours a day on a project during junior and senior year did not help my grades. My counselor told me that I wouldn't get into the top colleges because of this reason. I believed her and didn't apply to my dream colleges."

On the other hand he mentions that he might apply to other colleges in his junior year, with various recommendations from MIT, UC Berkley and UC Santa Cruz. So not all is lost.

Can't imagine a college that wouldn't jump at the opportunity now. Might be a solid first lesson on the real world - people that don't understand will be naysayers, and those that do will marvel at your work.

Maybe he should just take a year off? Keep working on this or other cool projects and apply next year. Might be worth it if he lands a serious scholarship from an elite school.

Speaking from experience, taking a gap year was the best decision I ever made.

Same here: he could do a killer program like this(which I did) and apply when he gets back: https://www.wheretherebedragons.com/

looks a bit more like 'where there be cash... to take kids on guided tours of exotic locales' :)

Well, you can look at it this way, he would have never been well-served by the traditional society-determined path anyway. A project like this has the tendency to just blow away all other considerations.

If you were hiring for a physics position, would you take the guy who got straight A's on his physics coursework, or the guy who built an effing nuclear reactor in his bedroom?

The sad thing is that if you were faculty, looking for a graduate student to supervise, you'd probably pick the one with straight A's and no hobbies, because you could get them to do whatever you wanted, without risk of them getting their own ideas or leaving.

Like I said, he never would have been served by the traditional path. With that kind of talent and drive, you don't need the academy, the academy needs you. They'll find a spot for him.

That's probably not true. I have run into very few faculty who want to have robots working for them, and I know quite a few faculty who are suspicious of perfect transcripts from potential grad students because it often means they avoided difficult courses or outside projects.

>quite a few faculty who are suspicious of perfect transcripts

In an undergrad department meeting, the topic was brought up on "why your parents should not call or arrive at the school seeking to talk to professors about their student's grades."

It's an open secret at some schools, Harvard being one of the most famous, that if you're rich or well-connected enough, you get in and coast with a B average, with relative ease--a C average at the worst.

That's bio, this is physics.

Lol what. Grad school values independent research much, much more than grades.

I can't think of a single professor that this holds true for.

If this were true, letters of recommendation wouldn't carry nearly the weight that they do.

Almost there, but you lost it in the end. The straight A student would win not because he is less proactive but because he is more versatile to handle any task. Someone who is deeply invested in a technology from an early age will have seen lesser challenges and diversifications than someone who takes all courses all around.

>The straight A student would win not because he is less proactive but because he is more versatile to handle any task.

The straight-A student is certainly able to put their minds to whatever they are told to, at least enough to get an A in each subject (and possibly no more).

I am faculty, and I wouldn't.

Adding to what others have say, in my department the choice would have been a no-brainer for the guy that has proved he can self-teach and do independent research. There's nothing faculty loves more than motivated people that can do a lot by themselves with just little directions from them!

There is very little about a university education that requires it to be "the traditional society-determined path." It's daily lectures and some work. There is plenty of time to be creative.

There's more to life than applying for jobs.

Underrated comment.

This dichotomy isn't the actual choice, though. You'd hire the person with straight A/A-'s (read: nobody cares about perfect grades) from Stanford/Berkeley/MIT/Caltech who also worked directly with some well-known professors, publishing papers that advanced the field, albeit incrementally, either building experiments or developing theoretical results.

In other words, the person who has demonstrated solid abstract knowledge (breadth/versatility) and actual ability to do research (depth/hands-on).

I could be wrong, but isn't this a situation where a university like CalTech would take a student like this?

CalTech takes in 200 total freshman a year (well back in 1999 it was 200) from the entire world, so they'd just choose the kid who built his own reactor AND had straight A's.

Something similar happened to me, I managed to end up somewhere close to what I wanted to be doing, but had I gone the "traditional" route it'd have been much easier with the same result.

But not as much fun? :-)

And at least from my experience, that is wrong wrong wrong.

I was a solidly B student in high school, but I had some extracurriculars (not quite building fusion reactors) that I devoted an absurd amount of time to and excelled at. And I got into MIT.

If you don't mind me asking, how long ago was this?

Not op, but for me getting into MIT was fall of 1997.

Yeah, I ask because the highschool workload and expectations have frankly changed. Being a solid B student doesn't get you into MIT (at least, that's what is drilled into your head)

Honestly, there are bunches of people with really impressive EC's that also have top GPAs and 99th+ percentile SAT's.

There can't be THAT many. Unless my math is wrong, they can only be at most 1% of the folks taking the SATs, right?

1,700,000 SAT takers -> 17,000 people in the top 1%.

Selecting the top 10% of those gets you 1700 students, which is quite close to the size of Harvard's acceptance statistic (of 2000)

Your implicit assumption is that anyone with a top 1% SAT score would also have good ECs and 4.0+. This is untrue.

That was sort of my point, and I didn't finish it, although the OP just said "bunches", which could be any number.

The person you're replying to indicates that 10% is 1700, and that 10% may be more representative of the high-EC and 4.0 level.

I'm not sure a few thousand folks from around the country qualifies as 'bunches'. Thinking back to my high school days, we had only a handful of people who were both academically advanced and active in many EC - sports, music, theater, etc. Partially there's just not enough time in most people's days to get 'good' at multiple things, even if there's aptitude. Secondly, not everyone can actually afford to get involves in a lot of ECs (despite aptitude/talent).

I can't think of anyone I know from my school (class of over 600, IIRC) who was all 4.0 GPA who also did multiple EC work. We had people in both camps. And I had a pretty lousy GPA, but did much better on ACT than some of the high GPA kids.

I bet more than half do. Tend to be the over achiever life.

No, my assumption is that there are perhaps 10% of people with high GPAs, and those with a top 1% sat score are no exception.

>Being a solid B student doesn't get you into MIT (at least, that's what is drilled into your head)

I know someone who got into an MIT engineering program roughly around '03 and they claimed to have below a 500 on the old SAT verbal section (scored perfect 800 the math though).

Their claim was they purposefully did not study for the verbal section because 'excelling at rote memorization to get into the top schools in the world is idiotic at best,' something like that.

This person claims she got into MIT in 2006 with a SAT a 1430 SAT I (which I guess would be, say, a 2150 or so now)[1]

[1] http://mitadmissions.org/blogs/entry/how_to_do_everything_wr...

I would have to imagine these days average high school GPA for incoming freshman to MIT is > 4.0

average != minimum

No need to imagine. It has been sampled and estimated: < 4.0 [0]

'04-'05 seems to be the last year MIT reported high school GPA's [1]; probably because the number is meaningless.

[0] http://www.acceptancerate.com/schools/massachusetts-institut...

[1] http://web.mit.edu/ir/cds/2005/c.html

To add on to amluto's point, that's because your average elite college admit is cookie-cutter: great grades, great test scores, probably did a sport, did some extracurriculars with some leadership/responsibility. A cookie cutter average admit to MIT needs great grades to be competitive because they all look similar.

Standing out exceptionally in one category (such as extracurricular projects) is not something the average admit to MIT posseses.

Being in almost exactly the same boat, I would have to agree. I was a decent student in high school. There were those in my class who were certainly better off academically in terms of GPA, those who presented at ISEF, etc. When that handful of students and I applied to MIT however, only I was admitted, for reasons I attribute to my passions and interests which I simply could not have explored in a meaningful way through any "sanctioned" or school-sponsored activities.

My guidance counselor as well as extremely discouraging, however after being at MIT for two years, I'm inclined to say that admission to a university like mine hinges on both being an interesting person and possessing demonstrable intelligence - not necessarily through scholastic channels.

MIT always had that reputation though.

You must have gone to a pretty good school district because the school district I was in was so bad many elite schools told us not to bother even if you were valedictorian. The quality of education couldn't be trusted to indicate possible future success at their institutions.

That's interesting - never heard anything like that. Where did you go to high school? The idea of elite schools saying not to bother doesn't sit right with me - a lot of the top schools pride themselves on finding diamonds in the rough, and that would run counter to that.

Also, take a look at his writing ability. He makes a couple of long posts further down the thread where he describes how the thing works. It's really quite good writing by any standards, which tends to be quite important for (and, I suspect, highly valued by) colleges. I know my own writing ability was nowhere near that level when I was his age.

Is there something lesser about going to a state school?

I didn't build a Farnsworth Fusor in high school but my school is ranked about the same as UCSC, hah.

Yes, pay. Note that the "public" schools on this list are service academys.

http://www.payscale.com/college-salary-report/bachelors

But don't people say that "school doesn't matter" for Engineering?

I agree it does matter - that's just the argument that's used.

This is pretty typical of guidance councilors at my high school as well. I went to a fairly poor public school and we were advised not to apply to extra colleges because we probably wouldn't get in and considering most of the student body lived around the poverty line the costs of applying to a bunch of colleges gets expensive fast.

Seems like he should have absolutely no problem transferring wherever he wants after this.

That comment is why I submitted this. Shame on that counselor for saying that, they should have been encouraging him to go for his dream! Building a fusion reactor should get this kid an invite to somewhere like MIT (as Ahmed Mohamed did for the clock incident last year).

In slight defense of the counselor, lots of kids have outside interests and projects that cause them to lose focus on their studies and not obtain the grades they were capable of. Very very few of them have the skills and sheer determination to actually deliver. Shame on the councellor for not seeing the finished project in senior year and pushing to get this kid some more opportunities (not that UCSB is a bad school by any measure).

They probably saved themslves years of ridiculous BS, poor instruction, and a mountain of debt. Good for them.

Same thing happened to me. I almost dropped out of HS because I got admitted to college early. I was administered a 'residual' ACT and was admitted.

The counselor told me people wouldn't want to hire me if I didn't have a diploma or a college degree if things didn't work out.

I honestly believe the counselor was looking out for me and wasn't incompetent, but christ I wish I hadn't listened to him.

Well, you need the second part of that comment to get the complete picture though:

> After submitting my college applications, I began making more connections. When I apply to other colleges as a junior, I will be getting likely 5+ recommendations from various chairs and professors at MIT, UC Berkeley, and UC Santa Cruz.

If someone reading this went to MIT and can contact admissions, they should link them to this story. Surely there are a few MIT alums on HN? Get this kid into his dream school!

Or maybe he mentions another school in the AMA?

A video of their reactor setup, including a part where they prep and run it.

https://www.youtube.com/watch?v=92M5qcjDkaU

This is great. A couple of high school kids just blew me away. I had to look up safe radiation levels after watching their Geiger counter. (Apparent answer: that's a lot of radiation, but a pretty short exposure.)

Side note: the view of the hills and mountains from the reactor room is gorgeous.

> Side note: the view of the hills and mountains from the reactor room is gorgeous.

Agreed. The twins' fusor.net profile says the they live in Berkeley, CA, a suburb across the bay from San Francisco. At 1min into the video I'm fairly the shot is from Berkeley looking across the bay to San Francisco. The mountains in the background look like the ones just south of San Francisco.

If you head a bit farther up the hill from where they say they live, the view is quite pretty: https://simplyrunningonfaith.files.wordpress.com/2011/02/img...

Actually now I think about it the city of Berkeley passed an ordinance declaring it a Nuclear-free zone, so I wonder if this project is legal.

AFAICT, berkeley's nuclear free ordinance only covers weapons research and development.

Makes sense. The pair seem to know what they're doing, so they probably checked city law beforehand to make sure everything is alright.

The intent of the ordinance is also "to prohibit nuclear reactors." [1] No person shall operate or build a nuclear reactor the City of Berkeley, and that would probably include this project.

That's not to say I agree with it. Berkeley has long been a hub of unhealthy NIMBYism, and this law is a leftover from the Cold War. I'd like to see that change.

[1] http://www.codepublishing.com/CA/Berkeley/cgi/NewSmartCompil...

I read these things and I smile because the stories will help others step outside their self imposed limitations and do things. When I was growing up I had a number of people who allowed me to dream big things and try them out when others would consider them too much work or too crazy. I got there by reading stories about some of the earliest inventors of our time and their home spun laboratories.

There is a lot you can do with a supportive family.

I had a strict no "high-anything" rule for my basement bedroom. No high temperatures, no high voltages, no high amperages, no high velocity, no high pressure, no high vacuum, no high anything :(. At least I made my desktop sound like a jet engine, so that's something.

At least you can still experiment with vacuum pressures!

Liquid nitrogen here we come!

> no high voltages

So electron beams ahoy then? "But muuuum! -45kV is a LOW voltage!"

He also excluded "high velocity". No electron beams alas.

"Keep it under the speed of light, OK?"

"Deal."

No "high-anything" would mean something very different to most parents :)

I have to wonder if college is actually the right choice altogether. The brothers basically learned everything on their own and most importantly actually shipped. Seems like a solid investment for some tech company to just offer them a job doing whatever research work they want for a year or two and seeing how it goes. Supposedly there's a job shortage in tech...here's an opportunity to sign a couple of HS students that build a reactor (and some other cool things) for kicks. I mean yeah sure they didn't build a fancy webapp but surely people at Tesla, Google whoever read Reddit.

The pros for college are access to lab stuff and some smart people + what you learn. I believe they can do the learning on their own just fine and well access to cool tech toys is also readily available at most tech companies...and there's also a lot of smart people around.

I made a lengthy comment below about my son, but now after watching the YouTube video, I am sad I do not have the resources to let him have such equipment.

My son pulls off some cool experiments all on his own (I stay out of it apart from the phone call consultation, or YouTube video call) with salvage and other workarounds, with the money he earns and my contributions.

These brothers have a freakin' mini-Tony-Stark lab in their house! Good for them and their parents. I like to see money spent this way rather than traveling team sports and uniforms. My take is sciency types, aka nerds, indulge more in solitary sports - rock climbing, skating, biking if they have time away from building a frigging nuclear fusion reactor in the bedroom!

One of the things I discovered later in life was that all the things I thought I was too poor to do in highschool were never actually limited by the amount of money I had. It was mostly the work I was willing to put in. After some of the things I've done now... If I had just sat down and thought about it, I could have come up with a way.

Don't fret - constraints can be a boon, too, making your son more creative. It is not really important to build a fusion reactor, you can just as well build other cool things that cost less.

Or you can learn business and marketing skills, which you will need anyway if you want to do something great.

For example, your son could set up some sort of Kickstarter collecting money for his fusion reactor. Or get in touch with universities asking for help. And so on.

I mean I agree that resources make a difference - for example I have heard many science project winners actually had help and got to use their parents labs. But don't let it dissuade you, don't give up.

Thanks guys. This is why I visit HN regularly to read and hear others, and voice my own humanity.

He started down the Kickstarter, Patreon road, but after a slew of failed and negative stories this past year on unfulfilled projects, angry supporters, he decided to go it his own.

He does juice out as much as he can with what he has to overcome any given constraints, but that only goes so far. Believe me, I am now living in the rice fields of East Java, and sometimes no amount of time or creative thinking wins the day for certain things out here (lack of cobra anti-venom, or time to get it). I do enjoy the challenge though, and have done some cool stuff on a shoe-string budget.

He's starting his won business fixing things people otherwise throw out - The ReAnimators! (not of the Lovecraftian movie). Sort of like the old TV/Radio repair shops that are gone. The business would not be too viable years back, but there is a lot of movement this way - the environment, built-in obsolescence (which is now being challenged by consumer groups and repair-oriented companies in court), and the joy of keeping the old piece of junk you are comfy with!

Stuff like this always reminds me of this kid (adult now): https://en.wikipedia.org/wiki/Taylor_Wilson

also this one https://en.wikipedia.org/wiki/David_Hahn

It's the same group, and probably very similar devices. the fusor.net website is a community for building these things and has loads of plans and tips.

Do you know of site that has a directory of such forums? I find these forums of experts very fascinating but not that easy to find.

This is pretty neat, and I managed easily located plans for a DIY fusion reactor at home [0]. I'm curious if OP's build differs from these plans, and if so, how/why.

Digging into the wikipedia article I found this interesting/surprising:

Recent Developments [1]:

"Most recently, the fusor has gained popularity among amateurs, who choose them as home projects due to their relatively low space, money, and power requirements. An online community of "fusioneers", The Open Source Fusor Research Consortium, or Fusor.net, is dedicated to reporting developments in the world of fusors and aiding other amateurs in their projects. The site includes forums, articles and papers done on the fusor, including Farnsworth's original patent, as well as Hirsch's patent of his version of the invention."

Apparently there's an entire online community of amateur home nuclear reactor builders [2].

[0] http://www.instructables.com/id/Build-A-Fusion-Reactor/

[1] https://en.wikipedia.org/wiki/Fusor#Recent_developments

[2] http://www.fusor.net/

fusor.net is the hub for these things, it's really quite an impressive resource. He says in the AMA he's registered there.

Reminds me of Phineas and Ferb:

"Aren't you a little young to be building a nuclear reactor?"

"Yes, yes we are."

This is so great to see young people accomplish such greatness, compared to world news lately

Amazing work by this young man! My children will love this.

My son and daughter are both doing well, but my son loves to experiment outside of school.

I have been encouraging my son to experiment and learn, and he has taken it to a higher level than I had imagined. I have bought him a telescope, and a 3D printer over the years. He works for his own equipment and supplies too. More each year.

Some of his experiments or demonstrations are recreated and slightly modified YouTube projects, and others are very original. I always tell him that being able to duplicate somebody else's work is good practice to learn proper rigor and familiarity with equipment and practices.

He is now a senior in high school, maintaining an A+ (>= 95) average in honor and AP classes. He won best Chemistry project in the whole county.

His biggest complaint is the amount of homework schools still dish out, several hours (3 to 4) each night. It takes away from his self-teaching and experimentation. Disclaimer: I am not too keen on public or institutionalized education. I think you learn more by doing projects that tie-in various disciplines, and accordingly I dropped out of college in the 80s to follow my passions. I've done well for myself considering I grew up below the poverty line when I was younger.

I was smelting metals in the 90s in my rural backyard without the internet or YouTube, and playing with TV cathode ray tubes in the late 70s. The former I could not have done where I grew up in Brooklyn, the latter was good to do most anywhere while tube sets were still around ;) I once tied the negative lead of a 9 volt DC transformer to my then sick Mom's big toe, and the other to a potted fern with copiously-watered soil, and then touched her same top foot with a connecting lead from the plant! Yes, stupid, but I was 10, and I had just read Frankenstein. Plus my parents were very positive about my inquisitive nature and doings. Mom passed in her older years, but never forgot the incident in a proud way.

My son is thinking on going to Germany for school due to the quality of education, and the fact that it is now free (almost, minus taxes and other expenses) for foreigners as well as citizens. He is also considering just starting on his own after high school, since he has acquired my distaste for institutionalized learning. The short of this bias: age-segregation, broken curriculum, non-integrated areas of study, homework and memorization over problem solving, etc. You can't even do certain experiments in school because they are considered too dangerous, or inappropriate. I do not try and push him too much either way. My ex-wife, is more conservative, and is hoping he will go to university.

Time will tell...

What were you hoping would happen to your mother?

I was hoping I could somehow sap the plant of some or all of its life force to bolster my mother's health. I even knew then it was a bit of quackery, but I was more evenly split between just doing and just thinking. Nowadays, I feel I have strayed to the too much thinking, or 'paralysis by analysis' syndrome.

Years later I read a fringe 'science' book about bioelectricity and limb regeneration. I guess I never kicked the Frankenstein thing (I visited Mary Shelley's grave site in Bournemoth, England in the 80s). It seems to be making a real science comeback. [1]

[Edit] the fringe book I wrote of was 'The Body Electric' mentioned in the article I cited just before.

[1] https://medium.com/matter/could-this-man-hold-the-secret-to-...

What would happen if he skipped on the homework?

Not sure, but I think it still counts as a percentage of your grade. I see where you are going with this, and frankly, if it accounts for 10 to 15% of the final grade, he would have a 90 or 85 grade, since he is doing so well. It would take away options for university if he decides to go here in the U.S.

Your son may enjoy universities with project-based curricula like Olin College.

Thanks for helping me pull my head out of my ass. I never heard of Olin; I'll check it for sure.

It looks like a great school!

"living things should not be within 35 feet as x-ray radiation is quite high"

hopefully this is a house in a low-density suburb and not an apartment. amazing achievement, but at the same time very dangerous to be generating x-rays out of your bedroom.

He probably didn't actually run it in his bedroom, just built it there.

Um... https://www.youtube.com/watch?v=92M5qcjDkaU

(From another top-level comment.)

Yeah, after I posted, I saw a comment saying his mom would leave the house whenever he wanted to run a test. Crazy.

On the other hand, that's one hell of a mom. I figure most moms these days would shut the project down from the get-go.

Let's hope there is some supervison.

There had been kids who built atomic reactor in their parents house and garden shed. Needless to say it's nowadays a superfund site and some people suffer from poising and radioactive materials. I think there is even a documentary about the boy scout guy who built a atomic reactor and afaik it was on HN before.

[disclaimer: While the reaction vacuum chamber seen in the video can be found at universities and is certainly less harmful than an open atomic reactor (see real boy scout guy story from above), it never the less involves substances that have to be handled with great care]

Edit: the boy scout guy David Hahn built an radiactive reactor at home, he was 17 years: https://en.wikipedia.org/wiki/David_Hahn

That was most likely a fission reactor.

In this case it is a deuterium-deuterium fusion reactor and both the fuel and the waste (helium 3) are pretty safe to handle. The device is only radioactive while it is operating.

That being said, he did say that he got tons of help from professors so at the very least he knows exactly how to remain safe.

He made it into the Neutron Club, people who have generated neutrons from fusion reactions: http://www.fusor.net/board/viewtopic.php?f=54&t=13

Wow! I wonder what exact steps are involved in getting from "I want to build a fusion reactor" to actually having a working prototype in your room. He mentions fusor.net; am I right in assuming that there are entire communities dedicated to building this kind of stuff? What is their history? How did they get started? Were they around before the internet? Fascinating!

Hypothetically, if you were the parent of such a child (or such an adult offspring), how should you make sure that they stay safe if what they are working on is beyond your capacity to evaluate?

I wish I had grown up in an environment flush with resources for this kind of thing.

The link is returning a 503 error: "all of our servers are busy right now. please try again in a minute"

Looks like the Fusion Reactor story caused a meltdown of Reddit's servers :)

Was probably a hiccup, the AMA loads fine for me now, and I'm on free airplane wifi :)

Who backed these guys financially? And how much did they spend?

The AMA says 6k. They got it from working part-time and family

Amazing accomplishment from such a young team.

I'm mostly concerned that he's going to get sick from improper shielding or something.

Creating a neutron generators is pretty trivial. Get some pyro electric crystal and apply heat. pyroelectric fusion nuetron genrator.

Maybe add a "Show HN: "

This looks more like a "Show reddit".

In before "is it energy neutral?"

He already answered that it's nowhere near the breakeven point. https://www.reddit.com/r/IAmA/comments/4tgsaz/iama_i_built_a...

It's a Farnsworth fusor, of course it's not. It's an enormous accomplishment for a couple of high school kids all the same - kind of makes you think of Rocket Ship Galileo, minus the moon Nazis.

This makes me think of "October Sky"

When people see something like this, I think they immediately think of Tony Stark, or the Wright Brothers. Something quite romanticized. This teenage is probably smarter than I am, but he's not breaking even in his bedroom.

He also mentions building a laser.

> a wood burning CO2 laser turret

I'd be interested in the details about that. I did some research about what it would take to build a basic laser years and years ago, but gave up when I saw the kind of chemicals I'd need to handle. I wasn't confident I could deal with the chemicals correctly in my tiny apartment.

I've looked into that as well. There are a bunch of lasers that are DIY-able, and AFAIK dye-based lasers are the only ones that really require "chemicals".

TEA lasers are basically just a few pieces of metal and high-voltage, seen them at high-school level quite a few times: http://www.sparkbangbuzz.com/tealaser/tealaser7.htm

CO2 lasers are relatively complex and are easiest if you buy some parts readymade, but can be completely homebuild as well: http://jarrodkinsey.org/co2laser/co2laser.html

There are tons of ressources online, a good overviw over different possibilities and basic information can be found here: http://www.repairfaq.org/sam/laserfaq.htm#faqtoc

If they weren't doing this in a suburb I'd say 'Congrats'-- but to knowingly be generating x-rays in a residential neighborhood is really, really selfish and disrespectful to neighbors.

They had measurements showing that outside the room there was nothing above background counts.

Still, I think if it had been me I'd have some lead shielding around it.

I think this is overstating the risk a little bit.

Looking at the video linked elsewhere, this was run in a bedroom on the second or even third floor of a single-family residence. He mentions not being able to detect x-rays more than 35ft from the device. I think a neighbor would have to be trying to get in range to be affected.

Here's the video again, queued up to the view out the bedroom window: https://youtu.be/92M5qcjDkaU?t=1m5s

On the other hand, if the neighbor's cat starts growing a third ear, they know who to blame! ;-)

One of the the few times where the inverse square law is helpful.

It's helpful all the time, since it allows stable orbits.

https://en.wikipedia.org/wiki/Bertrand%27s_theorem

Reminds me of this: https://what-if.xkcd.com/29/

What's lethal at 3 inches probably isn't measurable at 50 feet.

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