[bjvanles] refrigerated truck

the common belief goes, you never know when you might need to murder, so it is good to own a gun, and so many people do (under the pretense "self defense", of course).  by the same logic, you never know when you might need to move a body, so it is good to own a vehicle with a body-sized freezer compartment.

such a vehicle allows body disposal to be widely separated in both time and location from that of the murder, making it difficult for investigators to connect a found body (if ever found) to an earlier disappearance.  it can also buy time for the perpetrator to carefully plan how to dispose of the body, especially useful if the self-defense was spur of the moment.

"real friends help you move a body."  if you have a real friend with such a vehicle, the person storing and eventually dumping the body can appear unrelated to the murderer, similar to contract killing (hitman).

an RV (camper van) seems a good form factor for such a vehicle.  it is a common type of vehicle so won't arouse suspicion.  (tangent: but maybe it will arouse suspicion if you are black, as camping seems not a popular activity among African-Americans.  of course, doing anything while black arouses suspicion in America.  this method of surreptitiously disposing a body is therefore only available to white folks.)  it likely already has an onboard generator to power appliances while the vehicle is parked.  very large, or extra, fuel tanks to support long-running power are likely an easily available option.  (though well-insulated freezers can be very energy efficient.)  driving an RV into remote wilderness to dump a body will also likely not arouse suspicion: such destinations are common sites for white-people camping.

with enough time, a body can become freeze dried, though I think this works well only in a freezer with automatic defrost, which loses efficiency.  after freeze drying, there won't be as much smelly decomposition when the body is returned to room temperature and less chance for bodily fluids to be deposited where forensic detectives might find them.

if you want to freeze dry (or desiccate by any other means), should you instead use a dedicated device?  unfortunately, many (most?) chest freezers do not have auto defrost.  avoid upright freezers in general, but especially avoid those with non-removeable shelves.  how easy is it to modify a freezer to freeze dry faster?  for food storage, people typically want to avoid freezer burn.

hypothesize that one of the reasons why the murdered corpse of Geraldine Kelly's husband stored for decades in an unpowered chest freezer at a storage facility did not arouse suspicion is because the freezer had originally been powered on for a long time, long enough to (somehow) freeze dry the body.

automatic defrost (presumably) deposits the evaporated (sublimated) vapors of freeze drying into the atmosphere outside the freezer.  the vapors are mostly water, but could incriminating trace chemicals deposit (desublimate or condense) on surfaces outside the freezer?  can forensic investigators distinguish between trace deposits from freeze drying legal meat versus long pig?  maybe it is better to avoid automatic defrost and keep everything sealed inside.

things left in a freezer for a long time get frozen to the bottom and sides.  this could be a problem if you suddenly need to dispose of the frozen body in a hurry.  maybe a layer of sand or some other powder can lessen sticking to the bottom.  or, wrap the body, e.g., tarp, drop cloth, window film, shower curtain, before freezing.  how large does the wrap need to be?  it needs to be ready in advance.

the remains of leaked and desublimated bodily fluids, including sand, other powder, or wrap, need to be cleaned out of the freezer, a time-consuming operation.  how difficult is it to thoroughly clean a freezer, for example, the inside of its drain hose if it has one?

given how useful RVs would be for "self defense", it is surprising that they are not as popular as guns (or maybe they are popular for this reason but I am unaware).  it is surprising they are not restricted and regulated like guns.  although restricting RVs and chest freezers will make a lot of non-murderers unhappy, making non-murderers unhappy has not stopped gun (and other weapon) regulators.

merely brandishing a gun is often assault, the crime of threatening to kill.  should conspicuously owning an RV be also?  can one inconspicuously own an RV?

how difficult is disposing of the body compared to all the other tasks required for getting away with murder?  study the murderers who did get caught.

also inspired by Benjamin Beale, New Orleans.

previously, burning instead of freezing.

[gntvazct] commemorative honey

honey famously supposedly has extremely long shelf life.  package or repackage honey into very sturdy containers for long-term storage.  what containers are good for thousands of years?  plastic turns brittle.  rubber gaskets likely also go bad.

this is similar to old wine, sometimes also commemorative, so perhaps glass and cork is the right answer.

label (in a sturdy way) such a container marking a good event.  perhaps eat the honey later to commemorate the good times.

inspired by eating honey from the 1970s.  it tasted different from today's honey.  did the flavor change over time or did it start out that way?

[mtoycjhh] quadraphonic string quartet

some string quartet pieces might be best recorded with four separate channels then played through four widely separated speakers, so that the listener can more easily follow a melody or theme being passed around different instruments.  the instruments overlap in range, especially violin 1 and 2, and distinguishing them by timbre can be difficult.  direction is easier.

we only have two ears, so probably need a swiveling chair or to listen standing.  turning can help distinguish sound coming from an ambiguous direction.  should sound be able to come from above or below?  fancy hypothetical tech: headset that tracks your head orientation.  perhaps it communicates with the swivel of your chair.

which quartets?  or, compose pieces assuming this is how they will be played.  composer specifies direction of each instrument.  a piece could be played live with audience in center.  probably cannot have much audience because other bodies block and diffract sound.

generalizable to any music with a small number of instruments: polyphonic.

do we have the infrastructure to disseminate and play audio with more than 2 channels?  on my computer, even if there are multiple stereo audio output devices, there isn't an obvious way to play to more than one of them simultaneously.

inspired by Beethoven's Grosse Fuge, though it also has sections of big thick chords that might sound weird coming from different directions.

[iqzcqqxd] HEPA air filter not razors-and-blades

are there any room HEPA air filter machines not designed around the razors-and-blades business model?

the only thing I am aware of is building one yourself out of a box fan and 4 filters designed for full-home forced air ventilation systems.

there seems to be a healthy market for generic Aer1 (Holmes/Bionaire) filters.

[usvzlkbj] polyhedron with face plane formulae

create a physical model of a polyhedron with the plane equation for each face printed on each face.  this should be easy.

manually applying stickers is the straightforward method.  can it be automated?  a high resolution mill or 3D printer could engrave the information.

give formulae as QR codes to facilitate easy import into a computer algebra program.  also identify each face and include adjacency information.  list adjacent faces normally in (say) clockwise order, but counterclockwise if listing faces adjacent to an internal hole of a face.  is this enough to construct the polyhedron?

reading what's printed on the inner surface of a torus-like internal hole will be awkward; in general, reading convex faces.

previously, polyhedron facts as cards.

[nqmtuzvi] macrowave

what would it be like to cook with a microwave oven much more powerful than a normal consumer device?

using an electric stove power outlet, it would probably not be too difficult to draw 3x power.

can exhaust heat (from cooling microwave electronics) be harnessed?  microwave ovens are supposedly about 50% efficient.  maybe for warming water, always useful for cooking.

[ppvfjatl] programmable mouse

some features desirable in a hypothetical programmable mouse:

1. any (decent) programmable mouse can assign programmable mouse buttons to actions "button 1" (left click), "button 2" (middle click), "button 3" (right click), "button 8" (browser back), "button 9" (browser forward).  however, we would also like to access actions "button 4" (scroll up), "button 5" (scroll down), "button 6" (scroll left), and "button 7" (scroll right), assigning them to arbitrary buttons, not just to the scroll wheel.

   "button 6" and "button 7" actions are rare.  they are emitted by Logitech MX Ergo: the scroll wheel clicks left and right, which was surprising to discover.

2. the button numbers above are as reported by the xev program.  how large can button numbers be?  at first, the USB HID spec for mouse seems to suggest the largest possible button number is 8, but the common existence of button 9 (browser forward) disproves that.  we would like a programmable mouse to be able to emit button numbers as high as they can go.

3. clicking the scroll wheel left and right, mentioned above, is a desirable feature.

4. assign scroll wheel (up, down, left, right, and push) to arbitrary actions.

5. assign a button to mean double-click of a button action.  and triple-click.

6. scroll wheel acceleration: if the user makes many rapid "clicks" with the scroll wheel, it emits extra scroll actions (not one-to-one with clicks), allowing rapid long distance scrolling.

7. many gaming mice offer a button or two to adjust DPI.  let those buttons be programmable, assignable to something other than adjusting DPI.

8. drag lock: click a button once to send a button-down action, then click again to indicate button released.  LED or haptic to indicate that this is in progress.

[dwjgaijg] sophomore's dream guitar pick

at x=0, the functions x^x and x^-x are both tangent to the x axis (derivative is infinity).  this is not obvious from small plots.  limiting value of both is 1.

at x=1, slopes are 1 and -1.  both again have value 1, forming a right angle.

[pkqonadf] magnifying pill case

make it easier to examine the markings on a pill to verify that it matches what the label on the prescription bottle describes.  goal is to decrease medication errors, a major source of death.

construct a weekly pill case (one compartment per day) which has a built-in magnifying glass to view each daily compartment.  it should be possible to examine a pill in a compartment with the lid closed.  shake the pill case to flip a pill to examine markings on the other side of the pill.  perhaps a single magnifying glass that can slide to view each compartment, or one magnifier per compartment (less moving parts).

[yfibqmwy] press F to pay respects IRL

create a tombstone featuring the letter F, inspired by gaming.

for example, the F could take the place of the cross often prominently carved or incorporated into Christian tombstones.

more ambitiously, the F could be shaped like a button, suggesting people touch it.  (not actually a button because moving parts are fragile.)  perhaps it gets worn down over time if many people visit the grave and touch it.  a tombstone that invites an easy way for people to interact with it is a significant improvement over traditional tombstones.  it is vaguely like a tombstone with built-in vase that invites people to interact by leaving flowers.

the bronze statue of "John Harvard" has a worn-down foot where many people have touched it.

[ejdnedtu] 4900-piece pyramid-square puzzle

4900 square tiles: arrange the tiles in a 70-by-70 square to form a picture, similar to a regular jigsaw puzzle, except pieces don't interlock.

flip all the tiles over and rearrange the tiles into a 3D square pyramid: bottom layer 24-by-24, next layer 23-by-23, and so forth, up to one tile at the apex.  if done correctly, the pyramid viewed from above forms a different picture.

tiles have image portions printed on both sides.  to make things easier (if desired), texture or 3D shape can help distinguish which side is to be used for which structure.  tiles could also have a shape, like Lego, to help keep the layers aligned when building the pyramid.

pyramid has many tiles partially or completely obscured.  obscured parts can be left blank (making things easier) or have misleading false images printed on them.  or, there could be many possible ways to assemble the pyramid all having the same final shape but different pictures when viewed from above.

picture on the square side: Times Square.  picture(s) on the pyramid side: Giza pyramid complex.

the mathematical magic is 70^2 = 1^2 + 2^2 + 3^2 + 4^2 + 5^2 + 6^2 + 7^2 + 8^2 + 9^2 + 10^2 + 11^2 + 12^2 + 13^2 + 14^2 + 15^2 + 16^2 + 17^2 + 18^2 + 19^2 + 20^2 + 21^2 + 22^2 + 23^2 + 24^2 which has something to do with the Leech lattice and maybe the Monster group.  this is the only (nontrivial) equation of this form: 4900 pieces is the only number of pieces a puzzle like this can have.  cannonball problem.

if one or both sides of the puzzle are truncated square pyramids (unfinished pyramids), then there are more possibilities.

future work: investigate (truncated) rectangular pyramids.  a m-by-n layer gets a (m-1)-by-(n-1) layer above it and so forth, up to 1 by (1+abs(m-n)).

triangular or hexagonal tiles.

instead of tiles, consider cubes.  up to 6 different puzzles (with different final structures) could use the same collection of cubes.  the total number of cubes required will probably be enormous.

back to 4900 square tiles: what is a good brick-shaped case to pack the tiles for storage?  14*14*25, 10*10*49, 7*7*100.

[qigwvbhi] WRGBK cube

color 5 sides of a cube white, red, green, blue, black.  arrange many such cubes into a mosaic, turning each cube to have the face with the desired color showing.  (pretty sure that the primary colors should not be cyan magenta yellow for this application because colors do not overlap in a mosaic.)

one remaining face has not been assigned a color.  gray?  opponent process color theory suggests yellow, though that may be the wrong theory to apply for this application.

it's almost Rubik's cube.  peel off orange stickers to reveal black.  mosaics of Rubik's cubes have been done.

[fzmrfkok] T-shirt of Watson the number theorist

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89,... I don't understand.

(1/2 + 14.1i), (1/2 + 21.0i), (1/2 + 25.01i), (1/2 + 30.4i), (1/2 + 32.9i), (1/2 + 37.6i), (1/2 + 40.9i), (1/2 + 43.3i), (1/2 + 48.0i), (1/2 + 49.8i), (1/2 + 53.0i), (1/2 + 56.4i), (1/2 + 59.3i), (1/2 + 60.8i), (1/2 + 65.1i), (1/2 + 67.1i), (1/2 + 69.546i), (1/2 + 72.1i), (1/2 + 75.7i), (1/2 + 77.1i), (1/2 + 79.3i), (1/2 + 82.9i), (1/2 + 84.7i), (1/2 + 87.4i),... I still don't understand.

(data from http://www.plouffe.fr/simon/constants/zeta100.html)

Incidentally, the primes become less dense logarithmically while the zeros of the Riemann zeta function become more dense logarithmically.  (Previously.)  (Both exhibit "random" deviations from their statistical trends.)  Can this duality be illustrated elegantly?  Probably Chebyshev psi.  Crossover happens at the 24th terms, at the end of the lists above.

[mqoojdab] Clock with varying ticks

Create a device which sounds audible ticks all day long.  Inspired by a ticking clock.  However, unlike a clock, the tick rate varies by time of day.  One can roughly estimate the time of day by listening to the tick rate.  Maybe useful for the blind.

Perhaps tick rate smoothly decreases from 3 Hz to 0.5 Hz over the course of the day.  The abrupt transition from 0.5 Hz to 3 Hz at the beginning of the day is your alarm clock.

Inspired by a constantly ticking clock being generally not very obtrusive.

[yqkjnggp] Scratching with a diamond

The cool thing you can do with a diamond is scratch rubies and sapphires and tungsten carbide and everything else with it, including other diamonds.

(I think every other notable quality of a diamond is significantly exceeded in that quality by some other material.)

Create diamond jewelry in a form factor that facilitates scratching things with the diamond.

Stylus, or converts into a stylus: screw on a body.  Maybe pendant.

The diamond should have a cut that sharpens to a point, maybe the brilliant cut upside down.

Unfortunately, rubies and sapphires tend to be very small so may be awkward to scratch.  The diamond probably needs to be part of a precise tool, and the ruby or sapphire needs to be held very securely.  You will probably also need magnification to see the scratches on the softer material.

The other cool thing you can do with a diamond is see it resist being scratched by everything else.  The flat top of the brilliant cut might be good for this.  As before, there are numerous practical difficulties in demonstrating scratch resistance.

Perhaps yet another cool thing you can do best with a diamond is use it to apply high pressure: diamond anvil cell.  It's not so easy to tell that diamond is best, though.

[dtlxfpth] Three-way switch with push buttons

Consider replacing the common electrical setup of two up-down light switches controlling one light in XOR fashion with two push buttons.  Each push button toggles the current state of the light.  The wiring of the three-way switch remains the same: we are only concerned with the user interface.  Push buttons avoid the confusing local state of a light switch being on (up) but the light being off.

[xoyaoayd] Modern typewriter toy

Continuous feed paper from a roll.

Press a button to automatically type current date and time.

Of course, when you hit a regular letter key, the letter immediately gets printed on the paper, as a typewriter should do.

But also consider a line printer: a small display permits writing and editing one line, then a button commits the line of text to paper.

Additional buttons for TH, NG, AND.  Perhaps others.  Because a typewriter is always in typing mode, there's no danger of an accidental keystroke sending many characters to an application not expecting text to be typed.

Push a button to signal typing is done.  The typewriter then automatically appends a QR code version of what you've typed, so that what you typed can easily be scanned into digital form if desired.  Then, it automatically cuts the paper.

More toy-like features, intended for children: Large print (font).  This could especially be useful if the typist wants to leave a space to hand-draw an emoji.  Large-print keyboard.  Large keys.  Key layout ABC...Z, not QWERTY (but changeable).  Inspired by children being able to recognize letters before they can reliably write them by hand.

Freewrite is a vaguely similar product aimed for adults.  It does not provide the instant gratification of keystrokes being immediately committed to physical paper, though that's not its point.

Also vaguely similar, previously.

[vlgmippe] Soap sampler

Encourage hand-washing by making it easy for people to discover soaps pleasing to use for themselves.  Everyone has different preferences: different scents, different feel on the hands while using it, different feel on skin afterwards (e.g., moisturizing).  Make available sample-size samples covering a wide range of possibilities.

Inspired by COVID-19.

[qfqxmkuw] Emergency battery interface

A door lock with an electrical component will fail to function if it doesn't have electricity, for example, if its battery runs out.  If it is designed to fail secure, you won't be able to get through.

Provide a method to connect an emergency battery on the unsecured side.  Such a battery would be in addition to a secured main battery or other power source.  Someone worried about being locked out due to lack of power can carry an emergency battery to power the lock.  Of course, after getting in, one should correct the problem on the secured side that caused the lock to lose power in the first place.

Or, if one doesn't have a battery on hand when locked out, obtaining a battery is often much easier than obtaining a locksmith or other means to bypass the lock.

Assuming standardization, the same carried battery can power locks in many different locations, so it saves space over carrying multiple emergency keys.

Possible standardizations: AAA battery, coin cell, micro USB socket for power (attach a phone external battery).

Seen in a real device: 9V battery contacts.

[rysbedyh] Automatic light switch

Design a light with an ambient light sensor that automatically turns on the light when it becomes dark and turns it off when it becomes light.  This part is simple: many products already do this.

Fancier than that: a human can manually override the switch, turning the light off despite it being dark: perhaps it is time to sleep, or the human is leaving the room.  However, the manual override is not permanent.  The overridden light turns back on after another day-night cycle or light-dark cycle.

What should be the behavior if a light-dark cycle happens because of another light in the room has been turned on then off?  I think it should behave as if a day-night cycle happened: at least that is predictable and easy to understand.

The light automatically switches itself off when it becomes light.  This too can be manually overridden if the user wants the light on even if it is already light.  The manual override expires similarly after a dark period.  There might be a problem with a passing shadow on the light sensor being mistaken for a dark period.