The Straight Dope 05/09/2003

The Straight Dope -- By Cecil Adams
http://www.straightdope.com

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THE STRAIGHT DOPE 05/09/2003

Dear Cecil:

I conducted due diligence at your Web site, but
found no reference to a delicate but vital question
that has been nagging me for some time now. Can
you please tell me whether it is more sanitary to
aim directly for the back wall of a urinal or to
splash into the water? Which minimizes splashback?
Do urinal designers consider this in the same way
that, say, auto designers use wind tunnels to
minimize air resistance? This question takes on
heightened urgency when I visit guests' homes and
the issue of auditory embarrassment is considered.
--Mathias Dubilier, Burlington, Vermont

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Cecil replies:

Certain parties, and they're not all necessarily
female parties, are now rolling their eyes and
making eww-ick noises, the wusses. I'm sorry, but
there are things the world needs to know. We'll
call this discussion Men Are Pigs, Part Two.

Men Are Pigs, Part One, which surely few have
forgotten, dealt with the question of why toilet
seats in public restrooms are U-shaped. Answer:
To eliminate the part that men are most likely to
scuzz up. Urinal design is intended to address a
similar problem. Some men, of whom your fastidious
columnist is one, can use a urinal without soaking
themselves and the floor in the process. However,
judging from the swamplike condition of the average
men's room, the percentage of men who have mastered
this useful art is not significant. The principal
difficulty, which will surprise few women, is
improper aim.

For more, see:
http://www.straightdope.com/columns/030509.html

STAFF REPORT

Dear Cecil: 

If the Earth's sun was to lose enough mass to affect
the gravity field of the solar system, would the new
gravitational effect on Earth be felt instantaneously
or would it take 8 minutes or so (the light travel
time from Earth-sun) for the new equilibrium to
occur? -- Scott C., West Virginia

A few months ago I read a short article about how some
scientists were able to measure the "speed" of gravity,
but the article did not go into much detail and I never
saw anything else about it. So tell me, how did they
measure gravity's speed, and does speed vary the same
way force does, i.e., would the speed be different on
different planets? --Ron S., Portland, Oregon

SDSTAFF Chronos replies:

Now, this is a topic I can really sink my teeth into.
Is everyone comfortable?

First of all, there's no such thing as "instantaneous"
transmission of anything. Presumably, that would mean
that at the exact same time that the sun disappeared,
the planets would feel it (or rather, stop feeling
it). The problem is that you can't define "same time,"
unless it's also the same place. If, according to an
observer at rest relative to the sun, the two events
happened at the same time, then an observer moving
towards the sun from the Earth would say that the sun
disappeared before the Earth felt the effects, and an
observer moving in the opposite direction would say
the reverse: that the Earth actually felt the effects
before anything happened to the sun, which most folks
would gree is ludicrous. This may strike you as one of
those silly relativistic paradoxes--perhaps we can't
detect instantaneous events, but surely they can sure
occur, can't they? Sorry, but no, they can't. In the
Einsteinian universe, instantaneity--that is, event X
instantaneously causes effect Y at distance Z--is
impossible in a meaningful sense, since for reasons we
needn't delve into it would involve communication at
faster-than-light speeds. As you suspected,
gravitational effects travel at exactly c, just like
light, so it would take eight minutes for us to know.

This inspires two obvious questions: (a) How do we know
gravity travels exactly at c? 

For more, see: 
http://www.straightdope.com/mailbag/mgravityspeed.html

STRAIGHT DOPE CLASSIC - 10/31/1980

Dear Straight Dope:

In every city I can ever recall being in, the major
taxi company, or one of the major taxi companies,
is the Yellow Cab company. I know Star Trek
postulated theories of parallel development, but
there must be some other reason for yellow being
the color for taxicabs. Please satisfy my curiosity
on this bit of arcane Americana.
--D.C., Washington, D.C. 

Cecil replies:

It does seem a little suspicious, especially when you
consider that at one point there were 1,300 North
American cities or towns with Yellow Cabs. We owe it
all to one John Hertz, a Chicago entrepreneur whose
name is most commonly associated today with rental
cars. An Austrian immigrant, Hertz spent his early
years engaged in such Horatio Alger-type occupations
as hawking newspapers and driving delivery wagons,
all the while looking out for the Main Chance. He
found it in 1905 in the person of Walden W. Shaw, a
wealthy young gentleman who needed a partner to help
save his foundering auto dealership. Hertz served
admirably in this role, and restored the company to
prosperity--so much so that Hertz and Shaw soond found
themselves with a surplus of traded-in cars. Hertz hit
on the idea of using them to establish a taxicab service,
like those already in operation in New York. He decided
that the secret to success in the cab biz was high
visibility, so he commissioned a local university to
"scientifically ascertain which color would stand out
strongest at a distance," as his biographer notes. Yellow,
needless to say, won, and thus was born what eventually
became the Chicago Yellow Cab Company. After enduring the
usual travails, Hertz succeeded in building the company
up into the largest of its kind in the world, operating
some 2,000 cabs.  

For more, see:
http://www.straightdope.com/classics/a1_192.html

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