explain xkcd - User contributions [en]

2327: Oily House Index

2023-04-30T10:24:26Z

172.68.51.204: /* Explanation */

{{comic
| number = 2327
| date = July 1, 2020
| title = Oily House Index
| image = oily_house_index.png
| titletext = We're underwater on our mortgage thanks to the low price of water.
}}

==Explanation==
In economics, an {{w|index (economics)|index}} is a statistical measure of change in a representative group of individual data points. Common indices include NASDAQ (a measure of a range of stock prices) and a consumer price index (a measure of retail prices)

This chart demonstrates an invented index, the "Oily House Index", which measures a ratio of oil price to average house prices, over time.

The numerator is the average price of a new home (presumably in the US), in USD per square foot ($/sqft). It does not specify what kind of home, or where. One available metric is the [https://www.statista.com/statistics/682549/average-price-per-square-foot-in-new-single-family-houses-usa/ average price per square foot of floor space in new single-family houses in the United States] which was $118.91 in 2019. The caption refers to converting the ''mortgage'' of the new house (that is, how much the purchaser borrowed, which could be zero), while the definition simply refers to the ''new home price'' (the total value). It is not clear which of these two is used in the chart.

The denominator is the price of oil in USD per {{w|barrel (unit)|barrel}} ($/BBL). This is also not well defined, although the chart's caption suggests that it is based on crude oil. There are many different indices for different blends of oil in different locations, such as [https://www.investopedia.com/terms/w/wti.asp West Texas Intermediate], which is a crude oil commonly used as a global oil benchmark. (Others include Brent and Dubai Crude). The WTI price fluctuated around $55-60 throughout 2019. A barrel is a standard unit of oil volume, defined as 42 U.S. gallons (roughly 5.615 cubic feet or 0.16 cubic meters).

The comic then applies {{w|dimensional analysis}} to this index: dividing $/sqft by $/bbl yields a result whose dimension is a linear measurement, which can be called length. 1 barrel is 42 gallons, a gallon is 231 cubic inches, and a cubic foot is 123=1728 cubic inches, so a barrel is approximately 5.6146 cubic feet and a cubic foot is approximately 0.1781 barrel. The average price per square foot of a new single-family dwelling in the USA in 2019 was about $119/square foot, while the price of oil in mid 2019 was about $60/BBL or $10.7/cubic foot. Dividing $119/square foot by $10.7/cubic foot gives approximately 11.1 foot. This is slightly lower than the value shown on the chart of around 15.

The chart's caption then interprets that length as the depth that a new home could be filled with the crude oil that could be purchased with its price. For scale Cueball and Megan has been drawn, and the ceiling height of a typical house has been indicated, showing that only in time with deep crisis will the oil not fill the house. It's also not exactly clear where the extra oil should go after a multi-story house has been filled; on the top floor, you could just take off the roof and let the oil pile up (perhaps after building some retaining walls), but on the lower floors, there's already oil above the ceiling.

The index is high when house prices are high and oil prices are low (such as during the 1999 oil glut), and low when house prices are low and oil prices are high (such as during the 1979 energy crisis). See details about the [[#Chart|chart]] below.

The title text, "We're underwater on our mortgage thanks to the low price of water", is a pun. A mortgage on a property is considered to be [https://www.investopedia.com/terms/u/underwater-mortgage.asp "underwater"] when the value of the mortgage exceeds the value of the property. This is bad for both the owner (who owes more money than the property is worth) and the bank (who now have a loan which is not fully secured against a default: if the property owner defaults, the bank will lose money in selling the property)- though obviously far worse for the owner.

The title text is hinting at an alternative index based on the ratio of house price to the price of water instead of oil. At the 2019 rate of $118.91/ft² and a rough [https://www.pvwc.com/story_of_water/html/costs.htm average water price of $0.0015/gallon], a house would have to be filled with water to a depth of 1060 ft for the house cost to match the water cost. If the price of water fell or the house cost per square foot rose, then the index would rise, causing the house to be even deeper in water (following the metaphor of the index as filling the house with physical water). This situation could arise even if the property value remained high, although Randall may be humorously suggesting that the increase in the index would literally flood the property with water, which would then damage it, obviously decreasing its value. (If the index continues to be computed on average house prices, then this single event would not materially impact the index as a whole.)

In {{what if|11|What If #11 "Droppings"}}, Randall commented that "unit cancellation is weird" after making a similar calculation about fuel efficiency -- the European convention of presenting fuel mileage as "liters per 100 kilometers" represents an area (volume/distance), which can be physically interpreted as the cross-sectional area of a tube of gasoline with the total volume of fuel burned stretched out over the length of the journey.

===Chart===
;{{w|1979 oil crisis|1979 energy crisis}}
:In the wake of the {{w|Iranian Revolution}}, global oil supply reduced by only 4%, but caused widespread panic and a huge increase in oil price.
;{{w|Gulf War}}
:The {{w|Gulf War}} (August 1990 - Feb 1991) was the invasion of Iraq by the US, which decreased oil supplies and caused a spike in prices.
;1999 oil glut
:In early 1999, Iraq increased its oil production, while the Asian Financial Crisis reduced demand. Prices briefly fell to as low as $16.[https://oilprice.com/Energy/Oil-Prices/A-Recent-History-Of-Oil-Prices-History-About-To-Repeat-Itself.html]
;Ceiling height
:Reinforcing the connection with the metaphorical house filled with oil, "ceiling height" here is shown at somewhere just below 10 feet. The standard ceiling height in US homes is 9 feet for ground floor, and 8 feet on higher floors. [https://rethority.com/standard-ceiling-height/]
:Only twice has the height been below ceiling height, during the 1979 energy crisis, and in the beginning of the financial crisis of 2007-2008.
;Oil and housing crashes partly cancel out
:As a result of the {{w|financial crisis of 2007-2008}}, oil prices crashed from $147/BBL in July 2008 to $30 in December 2008. Meanwhile, {{w|United States housing bubble|falling house prices}}, which had partially triggered the financial crisis, continued to slump across the US, with the Case-Shiller home price index reporting its largest ever price drop in December 2008. Since both oil price and house prices were falling, the effect of dividing one by the other means that the index didn't change significantly, remaining around 8-15 feet.
;{{w|2010s oil glut}}
:In 2014-16 there was a serious surplus of {{w|crude oil}}, partially caused by increasing shale oil from the US and Canada, a slowdown in demand from China, and increasing fuel efficiency and use of renewable energy. Prices dropped from $125/BBL from 2012 to below $30 in January 2016. By October 2018, prices had recovered to $85/BBL. ]
;OHI briefly became infinite as oil prices reached zero in 2020
:In April 2020, the {{w|coronavirus pandemic}} dramatically reduced vehicle and air transport, crashing oil demand. [https://www.cnbc.com/2020/04/25/scary-visceral-unprecedented-traders-describe-oils-wild-week-and-fall-to-negative-prices.html Oil futures actually went to zero], and even below, several times: oil producers paying consumers to take their oil, to avoid the costs of storing it. Dividing anything by zero officially has no defined result, but in many thought experiments yields infinity, hence the "infinite oily house index". The graph should actually wrap around to the negative axis at this point.

==Transcript==
:[A line graph is shown. Above it is a rectangular frame with formulas inside. Most of the top part of the frame is removed and instead a heading is written over the missing section of the frame. The formula is written in three parts, with the first two parts having a division line with text written above and below.]
:Dimensional economic analysis
:New home price ($/sqft) / Oil price ($/BBL) = $/area / $/volume = Length

:[The graph has a labeled Y-axis with four ticks, which have values, and also the origin has a value. The X.axis is a time-line without label. There are five labeled ticks.]
:X-axis: 1980 1990 2000 2010 2020
:Y-axis label: OHI (feet)
:Y-axis: 40 30 20 10 0

:[Above the line graph there is a caption:]
:'''Oily House Index:''' How deep you could fill the average new home if you converted its mortgage to crude oil

:[The graph begins around 15 before 1980, then dips below 10, rises slowly until about 1988 when it rises sharply. It stays high but has several peaks, and one deep valley until 1999 when there is a very high peak, which then drops fast. A few more peaks, and then a decline to the lowest point in 2008, which is followed by a small peak, and then another drop. From there it stays low until 2015 when it rises quite fast and has one very high peak. It then drops of, until 2020 when there is a really sharp peak. Above the top of the peak is a dotted line extending to the top of the graph (i.e. the top of the Y-axis, not the top of the panel). Then it drops down but not very low as it reaches the present.]

:[There are six labels with arrows pointing from them to notable peaks and valleys along the graph. They are written both above and below the line. From left to right they are:]
:1979 energy crisis
:Gulf War
:1999 oil glut
:Oil and housing crashes partly cancel out
:2010s oil glut
:OHI briefly became infinite as oil prices reached zero in 2020

:[From 2005-2010 there is a dotted horizontal line that hits the valley at 2008. This is labeled with an arrow pointing to it:]
:Ceiling height

:[Below the line is a drawing of Cueball and Megan standing on the X-axis near 1990. Next to them is a label with an arrow pointing to them:]
:People (for scale)

{{comic discussion}}

[[Category:Line graphs]]
[[Category:Timelines]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Stock Market]]

991: Phantom Menace

2023-04-18T22:11:03Z

172.68.51.204: Undo revision 310648 by 172.68.50.72 (talk)

{{comic
| number = 991
| date = December 16, 2011
| title = Phantom Menace
| image = phantom_menace.png
| titletext = We could go to the theater across town and see if it's opened THERE yet, but we don't want to lose our place in line.
}}

==Explanation==
[[Cueball]] is waiting outside a building with an unidentified character, who is dressed as {{w|Darth Maul}}, a character from ''{{w|Star Wars: The Phantom Menace}}''. Before its release in May 1999, ''The Phantom Menace'' was one of the most anticipated movies of all time, with fans camped in lines outside of movie theaters as much as a full month in advance of ticket sales. In this comic, Cueball and his friend are apparently still waiting to see the movie, not having realized that they are waiting outside of a building that is not a movie theater. More importantly, they have been waiting for twelve years, which should be long enough to realize their error.

Darth Maul, the source of Cueball's friend's costume, is a Sith apprentice in the film. [http://starwars.wikia.com/wiki/Sith The Sith] are the group of characters in the ''{{w|Star Wars}}'' universe who embrace [http://starwars.wikia.com/wiki/Dark_side_of_the_Force the dark side] of [http://starwars.wikia.com/wiki/The_Force the Force] and are the enemies throughout the series. Cueball is holding a cheap replica of a {{w|lightsaber}}, which is the weapon used by the [http://starwars.wikia.com/wiki/Jedi Jedi] and the Sith.

This comic seems to be poking fun at those people who are willing to wait long in advance for the release of some product or the first theatrical release of a movie. The title text expands upon this when one of the characters states that going to a theater across town may be better, but he is worried about taking the chance due to the possibility of losing their place in this line, a misplaced sense of priorities if the line goes nowhere, and they are presently the only two in it.

==Transcript==
:[Cueball, holding a lightsaber, and another stick figure character in a Darth Maul mask stand on the sidewalk outside of a brick building in an urban area. Each is holding money in his or her hand. There is a broken window on the building.]

:[Beat panel. They continue to stand there.]

:[Beat panel. They continue to stand there.]

:[Darth Maul turns to Cueball.]
:Darth Maul: Are you ''sure'' this place is a theater?
:Cueball: Let's give it one more month.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics with color]]
[[Category:Star Wars]]

Talk:2752: Salt Dome

2023-03-21T10:03:15Z

172.68.51.204:

Made a guess. [[User:No Idea If There's A Character Limit LMAO|By me.]] ([[User talk:No Idea If There's A Character Limit LMAO|talk]]) 22:39, 20 March 2023 (UTC)

Odd that Beret Guy’s not the one doing it. We’ve seen White Hat act a normal extra character before, but having Beret Guy in a comic not doing anything strange feels wrong. [[User:Intara|Intara]] ([[User talk:Intara|talk]]) 04:09, 21 March 2023 (UTC)
: Agree. [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 08:37, 21 March 2023 (UTC)
:: I have just mentioned this in the explanation and compared Cueball's power with Beret Guys strange powers. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 09:39, 21 March 2023 (UTC)

The text mentions the UK Salt reserve, used to prevent black ice on roads. I assume that US states that get sufficient snowfall also maintain reserves of salt and grit to keep their roads open. Or does it simply get too cold for ice to be of any use? {{unsigned|Arachrah}}

Hmmm, I also see a somewhat indecent connotation between passing the salt and passing a kidney stone, in particular that the salt in the picture is being extruded through an orifice in the ground... -- [[Special:Contributions/172.68.138.179|172.68.138.179]] 09:55, 21 March 2023 (UTC)

Maybe Beret guy lended his powers to a geologist.[[Special:Contributions/172.68.51.204|172.68.51.204]]

Talk:2666: Universe Price Tiers

2022-09-02T07:36:02Z

172.68.51.204:

We seem to be in Universe Standard, based on the cosmic speed limit
[[User:Victor|Victor]] ([[User talk:Victor|talk]]) 22:03, 31 August 2022 (UTC)

Is the price per user (human)? Or payed by the "god" who runs the universe?
The interpretation would change quite a bit. If per user, some could travel fast while others would not see ads and could even be immortal.
If per universe, would the concept of ads disappear?
[[User:Victor|Victor]] ([[User talk:Victor|talk]]) 22:25, 31 August 2022 (UTC)
::The tree sound can't be a particular human's experience, and the speed limit seems intended to be per universe.

General comment, I think each line of the table should have a separate one-line or one-paragraph explanation, rather than squishing it into one column of a table which mostly reproduces the comic text. i.e. we don't need the table in the explanation, although it works fine in the transcript imo. [[Special:Contributions/172.69.62.71|172.69.62.71]] 23:40, 31 August 2022 (UTC)edit: a word

"Yes, and he cheats" may be a reference to a quote from ''Sid Meier's Alpha Centauri''.
::I fully expected something like ''"Most gods throw dice, but Fate plays chess, and you don't find out 'til too late that he's been playing with two queens all along."'' (from ''Interesting Times'' by Terry Pratchett) [[User:RAGBRAIvet|RAGBRAIvet]] ([[User talk:RAGBRAIvet|talk]]) 01:47, 1 September 2022 (UTC)
::The SMAC quote is "Einstein would turn over in his grave. Not only does God play dice, the dice are loaded. - Chairman Sheng-ji Yang", from the Probability Mechanics tech. Also, the "God does not play dice" quote is stated during the Supercollider secret project movie. I doubt the comic is referencing any particular media here, though. [[Special:Contributions/172.69.22.5|172.69.22.5]] 02:40, 1 September 2022 (UTC)
::Meanwhile, Stephen Hawking said "Not only does God play dice, but... he sometimes throws them where they cannot be seen." -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 16:01, 1 September 2022 (UTC)

Under ''Number of angels that can dance on the head of a pin'', '64' is 2⁵ and may be making reference to the Nintendo 64 game system. [[User:RAGBRAIvet|RAGBRAIvet]] ([[User talk:RAGBRAIvet|talk]]) 01:54, 1 September 2022 (UTC)
::And just for the record, 4096 is 2¹². [[User:RAGBRAIvet|RAGBRAIvet]] ([[User talk:RAGBRAIvet|talk]])

:: Note that the philosophical question of how many angels can dance on the head of a pin turns to have much more useful meaning if we realize that the question wasn't if 64 or 4096, but if it's a finite or infinite number, that is, if angels are subject to {{w|Pauli's exclusion principle}}. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 15:59, 1 September 2022 (UTC)

::: I think the answer is [https://www.imdb.com/title/tt8071704/characters/nm0000531 to be found elsewhere]. And it is a different power of 2! [[Special:Contributions/172.70.162.147|172.70.162.147]] 17:26, 1 September 2022 (UTC)

Who is paying our subscription? How do we ensure we don't get demoted to lite?

Here, the sound of one hand clapping is pretty much "toop." Put your hand out flat fingers together, and no thumb involved, quickly make a fist. Toop. Edit I'm not making a fist. Im keeping the last joints straight and smacking my hand[[Special:Contributions/172.70.134.95|172.70.134.95]] 15:59, 1 September 2022 (UTC)
:But two hands each doing that (or slapping another bit of body) aren't "two hands clapping", but more like two hands ''clasping''/something-or-other-like-that.
:If you could bring your one hand to a sudden stop in mid-air ''as if'' hitting another hand, it might be closer, but there's no sudden stop possible like a contact-stop. Plus a full-fledged clap for maximum ovational volume involves cupped hands trapping a resonant volume of air between them, almost sealed (wet hands so positioned can be used to force a squeaky-fart sound out from between them), and neither an "air clap" or the toop-clasp can do anything so dramatic with a solo hand. [[Special:Contributions/141.101.99.154|141.101.99.154]] 17:54, 1 September 2022 (UTC)
: the sound can be more clap like if you bend your hand upwards and keep it like that. Then loosen your fingers, and smash your upward lower arm to the front and back. My one armed brother taught me. It's handy (hehe) if one hand is holding a drink. [[Special:Contributions/172.68.51.204|172.68.51.204]] 07:36, 2 September 2022 (UTC)

I have a problem with the "Bad things..." portion. ''If'' I was a bad person, then I would never pay for the universe, as I would be better off in the free version, where nothing bad would ever happen to me. [[User:SDSpivey|SDSpivey]] ([[User talk:SDSpivey|talk]]) 19:17, 1 September 2022 (UTC)

The "bad things" section is a bit bothersome: good things don't exist without bad things. Without bad things, good things are just...things. So maybe awareness of bad things is still extant in UniPro? That way, good things would still be at the upper end of a theoretical scale.

But the subjectivity of badness is concerning in a bad-things-don't-happen realm. I reckon plenty of people who could spring for fifty bucks a month would list rum, Katharine Hepburn movies, gay people and Jews as bad things that therefore won't happen. If I stump up my Pro subscription, do I have to share the universe with these douchebags, or do we each get our own? And if it's the latter, how much of a douche must you be to be excluded from my universe? Can we differ a little and still coexist, or do we have to gel perfectly? And how would that ever happen...and would it be tolerable to live surrounded by my opinion-clones? Is this...is this the too-perfect Matrix v.1.0? Am I buying a ticket to a simulated utopia while my body atrophies?
You monster! Guards! Guards! Let me out.....

[[Special:Contributions/172.71.178.35|172.71.178.35]] 23:09, 1 September 2022 (UTC)
Note that Universe Lite is marked as trademark, Universe Standard as a registered trademark, and Universe Pro as...BOTH. This is a joke; more is better, esp. in lists of features. But there's no point in claiming a mark is both a trademark and a registered trademark.

How to clap with one hand: https://www.youtube.com/watch?v=qwoq3QBaQAY [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 04:38, 2 September 2022 (UTC)

If a tree falls in a forest and there's no one there to hear it, then there is NO SOUND. The act of the tree falling will create vibrations in the air, but those vibrations only become 'sound' when they impact on a tympanic membrane (such as an eardrum) that is connected to a brain. Sound happens in your head, folks. Of course, in practice, the likelihood of a tree falling in an area that contains NO tympanic membranes at all is impossible given the abundance of miniature scaled life on Earth. That said, we have no idea whether insects actually perceive those air vibrations as 'sound' in the same way that humans do - the fairy fly, for example, is so small that it can 'swim' through air rather than flying, so probably perceives sound waves the same way that humans experience ocean waves.

[[User:MarquisOfCarrabass|MarquisOfCarrabass]] ([[User talk:MarquisOfCarrabass|talk]]) 05:50, 2 September 2022 (UTC)

Talk:2656: Scientific Field Prefixes

2022-08-09T03:59:47Z

172.68.51.204:

Interestingly enough, the last time I was at a dentist, I ask them if they had seen any research work on how to do dentistry in zero-g, like if you got a toothache halfway to Mars.
[[Special:Contributions/162.158.107.56|162.158.107.56]] 01:58, 9 August 2022 (UTC) BCS

Those who say that there's no such thing as High-Energy Theology should be taken with a pinch of salt. Or even a {{w|Lot's wife|Lot}}! [[Special:Contributions/172.70.91.80|172.70.91.80]] 02:05, 9 August 2022 (UTC)

I'm a little concerned with Theoretical Theology. How much more theoritical can base theology be? [[Special:Contributions/108.162.250.198|108.162.250.198]] 02:22, 9 August 2022 (UTC) Beechmere

I'd love to conduct research on Marine Massage! How do I find the link? (Purposes.)

Talk:2656: Scientific Field Prefixes

2022-08-09T03:59:22Z

172.68.51.204:

Talk:2651: Air Gap

2022-07-28T08:26:55Z

172.68.51.204: Infrared conversion efficiency

Worth noting that this is a large and inefficient version of an [https://en.wikipedia.org/wiki/Opto-isolator opto-isolator] [[Special:Contributions/108.162.221.79|108.162.221.79]] 05:37, 28 July 2022 (UTC)

: Incandescent light bulb (assuming it the lamp does not use LED in the shape of light bulb) is not only less efficient than diode, but also much slower to warm up and cool down - it usually is much more sensitive to rapid switching, and has shorter life counted in the number of on/off cycles. --[[User:JakubNarebski|JakubNarebski]] ([[User talk:JakubNarebski|talk]]) 07:45, 28 July 2022 (UTC)

: I don't think it's less or more efficient than an opto-isolator, it essentially ''is'' just an opto-isolator. But an opto-isolator isn't supposed to be energy efficient to begin with; it's only designed to transmit data between circuits, not power. So the output side only needs to generate enough voltage/current to change the state of a transistor, and the input side only needs to generate enough light for the output side to do that. The voltages and currents involved aren't comparable to power circuits. --[[User:NeatNit|NeatNit]] ([[User talk:NeatNit|talk]]) 08:14, 28 July 2022 (UTC)

: By the way, wikipedia links can be written like this: <code><nowiki>[[wikipedia:opto-isolator|]]</nowiki></code> result: [[wikipedia:opto-isolator|opto-isolator]] (the final <code>|</code> automatically gets expanded to the article title without the <code>wikipedia:</code> prefix). --[[User:NeatNit|NeatNit]] ([[User talk:NeatNit|talk]]) 08:26, 28 July 2022 (UTC)

It is missing that air-gapping the power supply would protect your home from voltage surges in the power network caused by lightning strikes. Depending where the lightning hits the power network, there may be no fuses protecting your home or single fuses may fail to protect you. --[[Special:Contributions/172.70.246.115|172.70.246.115]] 07:57, 28 July 2022 (UTC)
:That is true. But the suggestion that this might have anything to do with general energy security (as is currently very prominent in the explanation) is entirely unconvincing to me.

Incandescent light bulbs convert most of their energy to infrared light. There are solar cells that work in this infrared spectrum, so this might not be all that inefficient as stated. This should in fact be a lot more efficient than any LED+visible spectrum based panel, as incandescent bulbs are very efficient in converting electricity into infrared light, much more than LEDs most likely will ever be.
The (mostly) omnidirectionality of the light source might be an even bigger loss, as most of the light (however efficient) does not even reach the panel.
And regarding sending data over this construct: As soon as there's a 0V state (which will be the case as soon as the transmission starts, due to some form of manchester coding, regardless of it being a 0 or 1 bit) the PC behind the solar panel would not only have a data transmission problem :)
(With incandescent bulb, that is. A LED 0V might be short enough for capacitors in the PC's power supply to buffer it, if it is only at 50%(+PSU conversion loss) load max, as manchester coded signals per definition have a duty cycle of 50% to keep the DC bias at 0V)
[[Special:Contributions/172.68.51.204|172.68.51.204]] 08:26, 28 July 2022 (UTC)

2649: Physics Cost-Saving Tips

2022-07-24T19:47:54Z

172.68.51.204: Revert vandalism

{{comic
| number = 2649
| date = July 22, 2022
| title = Physics Cost-Saving Tips
| image = physics_cost_saving_tips.png
| titletext = I got banned from the county fair for handing out Helium-2 balloons. Apparently the instant massive plasma explosions violated some local ordinance or something.
}}

==Explanation==
{{incomplete|Created by a FAUX VECTOR - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

This comic is another one of [[Randall|Randall's]] [[:Category:Tips|Tips]], this time to reduce costs or provide something for free for physicists to save money on their research. None of these would provide any real advantages even when possible to implement. It continues the previous [[2648: Chemicals]] comic's jocular theme of tricks to supposedly save money based on misinterpretations of science. Obtaining money from physics experiments was also described in [[2007: Brookhaven RHIC]].

{| class="wikitable"
|-
! scope="col" |Cost-Saving Tip
! scope="col" |Explanation
|-
|Try replacing regular vectors with pseudovectors whenever possible
|[[File:Torque animation.gif|frame|right|Relationship of pseudovectors {{w|torque}} ('''τ''') and {{w|angular momentum}} ('''L''') to "regular" Euclidian vectors {{w|Position (vector)|position}} ('''r'''), {{w|force}} ('''F'''), and linear {{w|momentum}} ('''p''') in an oscillatory rotating system. Not shown is the {{w|centripetal force}} of the spoke's {{w|Tension (physics)|tension}}, a Euclidian vector towards the axle proportional to linear momentum, converting it to angular momentum.]]

The prefix "pseudo-" refers to an inauthentic variation of something. Fakes are usually cheaper than their original brand-name product, while often working just as well, so the comic implies a {{w|pseudovector}} could be a less expensive substitute for a regular vector. On the contrary, pseudovectors, or axial vectors, are distinct from regular {{w|Euclidean vector}}s, the former usually being involved with rotation or physical effects that share properties with rotation, similar to the relationship between angles and lengths. Pseudovectors are formed from the {{w|cross product}}s of Euclidean vectors, in three dimensions, and while similar to Euclidean vectors, there is no physical meaning to their specific direction, only their magnitude and portions of their position. For example, {{w|angular momentum}} is described by a pseudovector, labeled '''L''' in the comic, {{w|Normal (geometry)|normal}} to the {{w|plane of rotation}}, originating from the center of rotation, with magnitude equal to the angular velocity of rotation '''ω''' multiplied by the {{w|moment of inertia}} '''I'''. (The comic's diagram is drawn according to very uncommon {{w|Right-hand rule#Coordinates|left-handed coordinates}} instead of the standard {{w|right-hand rule}}. Randall is right-handed.[https://www.youtube.com/watch?v=j1tcyEo2tQk&t=28s])
|-
|A square wave can be broken down into an infinite supply of valuable sine waves
|{{w|Fourier analysis}} can decompose any periodic function into a series of {{w|sine wave}}s. A {{w|square wave}} can thereby be represented as the sum of an infinite series of sine waves. However, the sine waves are not removed or separated individually, so such a {{w|Fourier transform}} does not produce a "supply" of sine waves for practical use in any tasks other than analysis, and as abstract mathematical objects exempt from the laws of supply and demand, their value is similarly limited.
|-
|Cut waste by buying lighter isotopes that don't have any dead-weight neutrons
|Chemical elements are identified by the number of protons in each atomic nucleus, equal to the number of electrons in their shell (unless the atom is ionized), which dictates most of their chemical behavior. {{w|Isotopes}} are variants of the element with different numbers of neutrons in the nucleus, among which chemical behavior is usually nearly identical. The comic suggests that the neutrons don't serve any useful purpose, so, in theory, if purchasing an element by weight, and its isotopes have the same price per unit weight, then you can save money by buying isotopes with no neutrons at all. In reality, the cost per unit weight for material containing a larger concentration of normally rare isotopes, such as {{w|heavy water}} or {{w|enriched uranium}}, is much higher than the cost of material containing isotopes in their ordinary proportions. (An exception is {{w|depleted uranium}}, which costs less than regular uranium because it is a byproduct of the production of enriched uranium.) In addition, a certain range of neutron quantity is needed to keep atoms stable, as atoms with too many or too few neutrons will decay more quickly than the common isotopes. The image shown is helium-2, an {{w|Isotopes of helium|isotope of helium}} which has a half-life of less than a nanosecond. It decays into two ionized hydrogen atoms, releasing a large amount of energy—hence the explosions mentioned in the title text.
|-
|Conductors are a great source of free electrons (may carry charges)
|{{w|Charge carrier|Free}} {{w|electron}}s are electrons that are not tightly bound to specific atoms so they can move freely, such as in {{w|conduction band}}s of the {{w|metallic bond}}s throughout the iron ingot depicted in the comic. Randall interprets "free" in a different sense, meaning no cost. The charges free electrons carry are electric, not monetary as implied by the pun.
|}

In the title text, Randall claims to have been banned from the county fair for handing out helium-2 balloons because of the instant massive explosions caused by its radioactive decay. He jokes they violated a local ordinance. Helium balloons are often given out at county fairs and similar events, but they are filled with helium-4 and therefore inert. A balloon filled with helium-2 is a practical impossibility because of its sub-nanosecond half-life. Assuming a 12-inch diameter balloon at 1 atmosphere of pressure, the balloon-bomb would have a yield of roughly 18 {{w|TNT equivalent|tons of TNT equivalent}}.

{{cot|[[User:SqueakSquawk4|Calcuations]]}}
{{User:SqueakSquawk4}} 
{{cob}}

The smallest nuclear bomb, the {{w|W54}}, had a yield of between 10 and 1,000 tons of TNT. The largest conventional bomb, the {{w|GBU-43/B MOAB}}, has a yield of roughly 11 tons. The {{w|2020 Beirut explosion}} was roughly equivalent to 500 tons of TNT.[https://link.springer.com/article/10.1007/s00193-021-00992-1] So, while the helium-2 balloon bomb would be larger than all conventional bombs, it would still be smaller than most nukes. Handing out what are effectively small atomic bombs at a county fair would not go down well with any surviving local authorities, so merely being banned is a very mild punishment. Criminal charges such as mass murder and terrorism would be more likely if it weren't for the absurd impossibility of the scenario.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[Title]
:Physics Cost-Saving Tips

:[A diagramatical spinning disc, at an angle]
:[It is identified with an 'I', with a dotted axial arrow labelled 'L' and a rotational movement labelled 'ω' (small omega)]
:[It sits on the left, and to the right of this is text...]
:Try replacing regular vectors with pseudovectors whenever possible

:[A square wave with three maxima (between four minima), and arrows pointing down into a collection of five sine waves of different wavelengths]
:[One of the waves having the same frequency as the square wave and the rest of them are of shorter lengths with more peaks and troughs]
:[It sits on the right, and to the left of this is text...]
:A square wave can be broken down into an infinite supply of valuable sine waves

:[Two atomic models]
:[The left containing two protons (white with a "+" sign), two neutrons (black) and orbited by two electrons (small outlines, dotted orbits/movement lines), labelled below with the text of superscript atomic weight and element symbol]
:4He
:[The right model has just the two protons and the two electrons, labelled below with the text of an atomic weight and elemental symbol, and some subtext within brackets]
:2He
:(Decays fast - use quickly)
:[Both models sit on the left of the comic, and to the right is text...]
:Cut waste by buying lighter isotopes that don't have any dead-weight neutrons

:[A flat rectangular bar, drawn in perspective with a scattering of dots/small circles on the top face and on the forward-facing one the label]
:Iron
:[An arrow points to the dots, from the text...]
:Free electrons
:[It sits to the right, and there is text to the left...]
:Conductors are a great source of free electrons
:(May carry charges)

{{comic discussion}}

[[Category:Tips]]
[[Category:Physics]]
[[Category:Chemistry]]