The Unofficial Unauthorized
Straight Dope Message Board
General Questions

By CookingWithGas

I started noticing a lot of the same questions, so I compiled an unofficial set of FAQs. This list is just the most common topics that seem to me to always pop up even though they are answered time and time again. The SDMB provides a comprehensive search function for more specific research.

When I attribute a post, it is to the poster who provided the link, not to the poster who started the linked thread. I have provided my own summary for many questions, though the summary reflects the discussion and not my own attempt to provide an authoritative answer.

Could Bill Clinton Run As Vice President? And other presidential term questions
Why don't we have metric time?
Why do we have different names for countries and cities than the natives of those places?
Do we all see the same colors?
If your car is traveling near the speed of light, what happens if you turn on the headlights?
Are generic drugs as safe & effective as brand names?
What happens when you are waking up or going to sleep, but can't move, and have hallucinations?
Why do all gasoline prices end in 9/10 of a cent?
Does .999... equal 1?
What is the correct way to make a possessive for words ending in "s"?
Should I use a comma before the last "and"?
Do skydivers breath through their skin?
Does hot water freeze faster than cold water?
Why can my car insurance company discriminate on age, sex, etc.? Do they/can they discriminate on race?
What is the most efficient way to set my home thermostat?
How does this online mindreading card trick work?
How does this online mindreading number trick work?
Tell me about copyrights
What's the best way to preserve the fizz in my soda?
Was the moon landing a hoax?
Can humans outrun any animal?
Will a frog allow itself to be boiled if you turn the heat up slowly?

Could Bill Clinton Run As Vice President? And other presidential term questions

Could Bill Clinton Run As Vice President?

Reference to these threads courtesy of brianmelendez:

Presedential [sic] Loophole
Max no of years as President?
American President and terms in office
Could Kerry choose Clinton as a running mate
Could Clinton become VP?
vice president requirements

Why don't we have metric time?

The question might be more properly phrased "Why don't we use a decimal system for time?" as suggested by scr4 in this thread.

Short answer: it's been tried, didn't catch on. See post by Exapno Mapcase for links.

Why do we have different names for countries and cities than the natives of those places?

A combination of
  • Using a pronunciation that is the best approximation possible in the language
  • Naming another country after a convenient or misunderstood appelation, such as naming an entire country after one tribe found in that territory
  • A best attempt at translation
  • Using a word that describes the people or country without regard to what its own people call it
If it's Deutschland, why do we call it Germany?
Cities/Countries whose Native Names are Different from English Names
Certain Languages Change The Names Of Geographic Places - Can You Provide Examples? (in IHMO, but still relevant)
Why can't we call folks what they want to be called?
Why Beijing but not München?
Why did we anglicise the names of other countries?

Thanks to Jervoise, more previous threads:

Country names, their origins, and a minor UN question
Names of Countries, but in other languages.
A question about the word "Germany"
The Dutch Netherlands

The Master Speaks:

Why are there so many names for Germany, AKA Deutschland, Allemagne, etc.?

Do we all see the same colors?

This question has yielded more than one interpretation. Color blindness aside, there may be physical attributes along the path from the point where light enters the eye to where the optic nerve connects to the brain that cause cognitive systems of different people to have slightly different responses to the same wavelengths. In fact, some people see slightly different colors in each eye. There are also people who, when looking at the same color, call it something different (". . .the green wall." "You mean the beige wall?"). However, the meaning probably intended is the question posed by sophomores in drug-induced stupors for decades, which is what the mind "sees" after the signal gets all the way to the brain. There is no way to compare what the actual psychological perception is, for example, when you and I both look at the color we both call "red," does my brain see a color that you would call "blue"? But there is no compelling reason to think that people would have dramatically differing perceptions of colors; the same thinking would apply to all of our senses.

Previous threads:

Do we really see the same colors?

If your car is traveling near the speed of light, what happens if you turn on the headlights?

The implied question is, "If you are traveling 1 k/hour below the speed of light then turn on your headlights, won't it look to observers in the car as if the light is getting away from them at only 1 k/hour?" The velocity of the light from the headlights will always be measured as the speed of light, regardless of whether the observer is stationary with respect to the car, or inside the car, or anywhere else. This is a basic consequence of relativistic motion, and is taken into account in equations to calculate such things.

Thanks to Fish Cheer ("Gimme an F") for the links:

If you are traveling at the speed of light in a dark tunnel...

The Master Speaks:

If you turn on your headlights while driving at the speed of light, what happens?

Are generic drugs as safe & effective as brand names?

Generic drugs are required by the FDA to have the same amount of active ingredient as the brand name, although other ingredients vary, such as coatings and fillers. Quality control in the manufacturing of generics can be below that of brand name drugs. There is also the possibility of the placebo effect with brand name drugs. Doctors have the ability to prescribe that no generic substitute is allowed; motivations for doing this range from a sincere belief that the brand name is better to an unethical allegiance to the drug company.

Birth Control Pills- brand names vs. generics

Links thanks to Exapno Mapcase

Generics = sickmaking, not brand?
Are generic drugs as effective as name brands?

In the above thread, kspharm, a pharmacist and guest poster says there is no difference. Another guest poster pharamacist, miatachris, recommends staying away from generics for some drugs, and cautions against switching back and forth for others.

Prescription drugs - "Brand name only if checked." Why?
Who manufactures drugs, and what is the difference between generic and namebrand?

What happens when you are waking up or going to sleep, but can't move, and have hallucinations?

It's sleep paralysis.

What causes sleep paralysis?
What IS this bizarre Nightmare-esque experience I had?
Can you induce Sleep Paralysis?

Hypnopompic hallucinations are a similar but distinctly different phenomenon:

Who knows about Hypnopompic Hallucinations

Why do all gasoline prices end in 9/10 of a cent?

When gasoline was down around $.20 per gallon, it was reasonable to price it in tenths of a cent when you were buying 10-20 gallons. However, as prices rose, the tenths have become nearly meaningless but carried along as a marketing ploy, even though everybody knows the ploy. The first gas station to change its price to $3.00 a gallon will suffer against the station down the street who still charges the "bargain" rate of $2.999. However, in spite of all the informative posts, I have seen none from an employee of the petroleum industry with an authoritative answer.

Gas prices ending with 9/10
Why do gas station prices end in tenths of cents (like $2.499)?
Why are gas prices quoted in tenths of cents?
gasoline pricing

Thanks to x-ray vision for:

Why do all gasoline prices have that extra "9"?

Thanks to pulykamell for:

Why do gas (petrol) prices always end in nine-tenths?

Thanks to Jasonh300 for:

gasoline questions (nothing to do with current prices)

Does .999... equal 1?

Yes. If you don't believe it just read the hundreds and hundreds of posts.

First, to clarify notation, this is a decimal point with an infinite number of 9's following. Normally this would be written with a bar over the 9 but that's a pain to put in inline text in HTML:


Posters have expressed several viewpoints in some of the more emotional threads on the board. Several mathematical proofs have been offered, although no mathematical refutations have. This issue is somewhat related to, but not the same as, the problem of expressing certain rational numbers in decimal notation (1/3 = 0.33333... in base 10, although is exactly 0.1 in base 3). A few key points:

  1. .999... and 1 are two ways of writing the same number, just like 1/3 and .333... are two ways of writing the same number.

  2. Some argue that .999... approaches 1 as a limit but is not equal to 1. However, this viewpoint erroneously identifies a fixed number as "approaching" another number. Numbers don't approach one another, functions and series approach limits.

  3. If .999... and 1 are different numbers, then you should be able to find a real number (in fact, you should be able to find infinitely many real numbers) between them (eloquently expressed by C K Dexter Haven). But you can't. If you subtract .999... from 1, you get a decimal point followed by infinitely many zeroes, which is zero. (No, there's not a 1 at the end because there is no end--it's an infinite number of zeroes.) This viewpoint was also espoused by DrMatrix.

  4. Also from C K Dexter Haven:
    The simple multiplication proof is usually sufficient:
    (1) x = .99999....
    (2) 10x = 9.999999...
    Subtracting (2)-(1):
    (3) 9x = 9, hence x = 1.

  5. 1/3 = 0.3333....
    1/3 + 1/3 + 1/3 = 1


    So 0.9999.... = 1

Math: .99repeating = 1? (featuring an interesting prereponderence of since-banned posters)
Why doesn't .9999~ = 1?
.99999999 equal to 1 ???
.999 = 1? (This one was started in 2000 and renimated in August 2012 adding 550 more posts)

The Master Speaks:

An infinite question: Why doesn't .999~ = 1?

Although this question hasn't generated a large number of threads, there are a large number of posts in these threads. I guess this shouldn't be surprising on a board where there are dozens of posts discussing a proof of 1 + 1 = 2

What is the correct way to make a possessive for words ending in "s"?

More than one. Here are cites I have found. These cites are all from educational or other somewhat reputable source, not just random opinions:

This one subscribes to the "just the apostrophe if it ends in S or Z or X" rule (the X and Z are new ones on me)

And one that subscribes to the "apostrophe plus S even if it ends in S" rule and another and another

And here one that sits on the fence, saying to add apostrophe-S but it's acceptable to omit the S

These guys consider the pronunciation as a mitigating factor. So do these guys but use a different rule

And this one's unique—it depends on how the next word starts

This one's confusing, taking into account whether it's a name, singular, plural, how it sounds and seems to give contradictory examples (Dickens's, Moses')

And I'll give these guys the last word, which is

"Since there is no agreement on this difficult problem, you must make your own choice. However, regardless of which option you choose, do remember to be consistent. "

Apostrophe rule concerning words ending in the letter s for ownership?
Apostrophe Use in Plural Last Names
Apostrophes and the plural possessive

Should I use a comma before the last "and"?

This is the question of which form is proper:

I had eggs, toast and bacon.
I had eggs, toast, and bacon.

The final comma used before the and, or, or nor is known as the serial comma or Oxford comma. This is not a grammar issue but rather one of punctuation style. There are equally enthusiastic advocates on both sides. Inevitably someone quotes the apocryphal book dedication (the origin of which I was unable to determine):

This book is dedicated to my parents, Ayn Rand and God.

The points of view commonly are expressed are either always use it, or use it only when necessary to eliminate ambiguity.

Lists, conjunctions and commas
Comma before a conjunction?
Punctuation Question: Lists of Three or More
U.S. grammar - can a comma preceed "and"?

Do skydivers breath through their skin?

There is a myth that skydivers absorb so much oxygen through their skin under the high pressure of free-fall that they don't need to breath through their lungs. Apparently the Discovery Channel and the developers of the "Worst Case Scenario" game propagated the error. There is no physiological way for this to happen. Google "skydiving breathing skin myth" if you don't believe us.

Breathing Neccessary while Skydiving?

Thanks to Johnny L.A.:

Do sky-divers breathe through their skin during free fall?
Skydivers don't breathe?

Does hot water freeze faster than cold water?

Well, yes and no. Cecil says "no," and then finds out that Scientific American says "yes." But they experimented with different initial conditions. It seems to matter what the temperatures are of the "hot" and "cold" water you are using. Factors that may come into play according to various posts are faster evaporation of the hotter water, dissolved gasses, suspended mineral deposits. Ultimately, if the only variable is water temperature and these other factors are controlled, the cold water freezes first.

Hot water makes ice cubes freeze quicker?
Which freezes faster hot water or cold water?
Freezing hot water - reprise

And a very good article, not an SDMB thread:

Can hot water freeze faster than cold water?

The Master Speaks:

Which freezes faster, hot water or cold water?

Why can my car insurance company discriminate on age, sex, etc.? Do they/can they discriminate on race?

Insurance rates can legally be adjusted to reflect certain groups, including sex and age. It is illegal to do the same based on race.

The fairness of insurance companies discriminating
So! Some occupations more equal than others, in determining auto insurance rate.
My insurance will be high!! Argh!
Your insurance co. and government sanctioned descrimination (from Great Debates)
Female=cheaper car insurance. Why is this legal?

What is the most efficient way to set my home thermostat?

Turning down the thermostat in the winter during certain times of the day and up in others saves energy only to the extent that heat loss is reduced while the thermostat is lower. This is because he rate of heat loss is related to the difference in temperature bewteen the house and the ambient air. The smaller the difference, the lower the rate of heat loss. Any savings from the dropping temperature when the thermostat is lowered are lost when you turn the thermostat back up again.

Cheapest/most efficient method of home AC use?

Many thanks to SDAB member Una Persson for the links provided in that thread:

Where should I set the day thermostat temp for max efficiency?
Electronic home thermostats. Whats the best temp to set it at?
Most Efficent Home Heating Strategy?

How does this online mindreading card trick work?

There is an online card trick available in lots of places where you are shown five cards and asked to select one in your own mind. Moments later you are shown four cards—the one you had selected is gone! The secret? They're all gone. Each card was substituted for one similar, like changing the Jack of Hearts to the Jack of Diamonds.

Computer card trick--how does this work
What's up with this card trick?
What the ??? How do they do this magic trick?
Card Trick...How does this work?

How does this online mindreading number trick work?

Here is an example. This trick usually goes like this: Choose any two digit number, add together both digits and then subtract the total from your original number. You are shown a table of numbers from 0 to 99, and you are to note the symbol by your final number. Then you click and the site shows you the symbol for your number!

Let's call the first digit of your number x and the second y. That means your number is 10x + y. Let's follow the directions.

Add the digits: x + y Subtract from the original number: (10x + y) - (x + y) = 10x + y - x - y = 9x

So your final number ends up being 9 times the first digit of your original number. This means that the final answer will be some multiple of 9, from 9 to 81. If you take another look at the table of numbers you will see that every multiple of 9 has the same symbol. To keep you confused, good implementations will change the symbols every time to keep you from detecting a pattern.

A "Mind Reading" Web Page
How does this trick work?
How does this number trick work?
Magic Trick: how?

Tell me about copyrights

Do I have to register my work? Do I need a copyright notice?

A work is copyrighted upon creation. No registration is necessary. Your work is copyrighted even if it does not carry a copyright notice, although the notice affects what kinds of damages may be recovered in case of infringement. This article has a good summary.

Fair Use

Fair Use is the principle that an individual who has purchased a copyrighted work may make copies of that work or excerpts for certain types of personal use, journalistic reporting, critique, and parody. The definition of fair use is not explicitly spelled out in law, and there appears to be no litmus test. However, commonly accepted guidelines for significant factors include:

  1. the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes;
  2. the nature of the copyrighted work;
  3. the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and
  4. the effect of the use upon the potential market for or value of the copyrighted work.
Examples that are not fair use:
  • Make a copy of a music CD then sell the original CD.
  • Make a copy of a CD or songs on a CD in any electronic form then give them to someone, which includes doing so passively by allowing access from a file-sharing system or posting to a web site to allow downloads. Just because you don't make any money from it doesn't mean it's not copyright violation.
  • Photocopy a magazine article if the magazine doesn't belong to you.

How long does a copyright last?

The U.S. government has a site describing this. Cornell University also has a summary. To summarize:

  • For works created on or after January 1, 1978, copyright is effective upon creation and expires 70 years after the author's death (70 years after the last surviving author's death in the case of joint works).
  • In the case of an anonymous work, a pseudonymous work, or a work made for hire, the copyright exires 95 years from the year of its first publication, or 120 years from the year of its creation, whichever comes first.
  • Works created but not published or copyrighted before January 1, 1978, become automatically copyrighted on that date and expire according to the previous point (with some exceptions, see reference).

How can two books/movies/plays/etc. have the same name?

Titles cannot be copyrighted.

The number of threads with "copyright" in the title was 124, last time I checked. The questions come in great variety. I am not going to provide links here.

SDStaff Gfactor and guest contributor acsenray Speak (at length, I might add ):

Part 1 Part 2 Part 3 Part 4

What's the best way to preserve the fizz in my soda?

Preserving Soda Fizz (though the thread starter was a guest with an attitude, responses do move the discussion forward)
Squeezing bottles and carbonation?
Retaining soda carbonation
Keeping soft drink fizzy
carbonation in soda
Does squeezing (and sealing) a soda/soft drink bottle keep it carbonated for longer?

Was the moon landing a hoax?

Thanks to zut:

Moon Landings: why is there no dust in the lander pads?
Please, for the love of Og, tell me we landed on the moon...
Moon Mystery
Skeptics about the lunar landing?
Have we really been to the moon or what?
Moon Hoax
"Was the mon landing a hoax?" Article
If we could land on the Moon 35 years ago, why can't we now?
So tell me something about this? Re- Moon landing pictures
Did Armstrong REALLY walk on the moon?
Caould anyone point me in the direction of a "moon hoax" debunking site please?
Did they ever land on the Moon?
Moon Landing - we really did this, yes?

Plus from The Mailbag: Was the Apollo moon landing a hoax? (31-Mar-2000)

Can humans outrun any animal?

Yes, if you define "outrun" as being able to outlast another animal in a race of endurance. Animals will overheat before the human.

Is it true that humans can outrun all other animals in the long run?/
A Man Can Chase Down Any Animal . . . Eventually (??)

Article that claims that "Biomechanical research reveals a surprising key to the survival of our species: Humans are built to outrun nearly every other animal on the planet over long distances." Chen, Ingfei, "Born To Run," Discover, May 28, 2006. Freely available online as of October 14, 2008.

Will a frog allow itself to be boiled if you turn the heat up slowly?

No. Moderator Colibri offers actual scientific information in two of these threads. And our old trusty Snopes also has an article on this topic.

is the "slowly boiling a frog" analogy BS?
Why do I know how to boil a frog?
Can you boil a frog alive, by turning up the heat so slowly it never notices?