Q:
How much does a little piece of a white dwarf weigh? (Shelia, Tualatin,
Oregon)
White dwarfs (circled) seen by Hubble Space Telescope. So dim that even
the brightest dwarf is no brighter than a 100-watt light bulb on the Moon.
Stellar corpses. [Harvey Richer (University of British Columbia, Vancouver,
Canada) and NASA]
A: I’ll give you answers but they vary by 5 orders of magnitude! Our
estimates range from ten thousand to one billion grams per cubic
centimeter — depending on whether the dwarf is a youngster or an old star.
"The newborn lightweight ones have larger diameters and lower densities,"
says
Harry Shipman, astronomy professor at the University of Delaware in Newark.
The very old, massive white dwarf stars paradoxically have smaller diameters
and, therefore, have the higher densities.
A teaspoonful of a baby white dwarf has a mass of 110 pounds-mass (50 kg) and
that of an old dwarf has 11 billion pounds-mass (5 billion kg). Immense!
Further Reading:
Hypertextbook by Michael Erber: White dwarfs
Royal Observatory Greenwich: White dwarfs
Q:
Assuming one can pick up the flu from money, how long does the virus stay
infectious on paper currency? Is it safe after it's been in my wallet for a few
hours?
(Lanney, Albuquerque, New Mexico)
Get a flu shot — the best way to avoid the
flu. [CDC]
A: I searched up and down the Internet hunting for an answer. Only to learn
that contact with money that a flu-infected person has touched is not much of a
problem.
Indeed, infected droplets are the main culprit spreading influenza viruses.
When someone with the flu coughs or sneezes, he shoots infected droplets up to
three feet away, says ConsumerMed. If these drops land on our mouths or noses,
we can catch the flu and likely will — especially if our immune system isn’t up
to snuff.
"Occasionally [emphasis added] a person may become infected by
touching something with viruses on it and then touching their mouth or nose,
says the Centers for Disease Control and Prevention (CDC).
So, sneezed-on money can conceivably spread the flu. Back to your question:
is money safe after a few hours. Probably. "Flu viruses can survive for hours on
surfaces such as doorknobs, light switches, phones, and office equipment," says
the Calgary Health Region in Canada
NOTE: Avoid close contact — especially with sneezers or coughers. Wash your
hands thoroughly and frequently so touching your mouth or nose doesn’t do you
in. Get plenty of sleep (8 to 10 hours). If you can, get a flu shot — the best
way to avoid the flu.
"Flu vaccine is about 70% effective, but is variable between years," says
Gail Sullivan, assistant research professor of medicine at the University of
Virginia Health Science Center.
Further Reading:
CDC: Key facts
about the flu
ConsumerMed: Influenza
Q:
I know that viruses spread colds but can getting cold or wet somehow make a
person more vulnerable to the cold virus? (Doug, Someplace, World)
Sick with a cold [CDC]
A: Another myth bites the dust — however reasonable it seems. No. People
don’t become more vulnerable to catching a cold because they got cold or wet.
We’ve looked into this one thoroughly and the myth isn’t true (unless, of
course, the cold is so intense that it destroys the body’s defenses, such as
freezing to death).
In 1958, H.F. Dowling exposed 400 volunteers to cold viruses. The volunteers
experienced different temperatures and dress protection — some shivering in
extreme cold of 10°F (-12°C)
but wearing heavy coats, others chilly in 60°F
(16°C) temperature wearing only underwear,
and still others sweltering in 80°F (27°C)
temperatures. They all, however, caught colds at "about the same rate."
Ten years later, R. G. Douglas, Jr. experimented in a similar fashion with
inmates at a Texas prison.
Again, no difference. The men caught colds at about the same frequency and
the resulting colds were about equally severe whether or not the inmates had
endured cold and no matter how they were dressed.
The National Institute of Allergy and Infectious Diseases (NIAID) also has
funded studies and found no correlation between getting chilled or overheated
and catching a cold. NIAID has found no relationship with exercise, diet, or
enlarged tonsils or adenoids either. They have found that psychological stress,
allergic disorders affecting the nasal passages or the throat, and menstrual
cycles can make a person susceptible to colds.
By the way, colds spread through touching infectious surfaces or inhaling
viruses. Cold viruses can survive for about three hours outside the nasal
passages. So, to prevent catching colds, we can:
- most effective: wash our hands
- also effective but much more difficult: don’t touch our
noses, mouths, or eyes.
Finally, over 200 viruses cause the common cold says NIAID. "Prospects for a
cold vaccine are dim."
Further Reading:
Myths of the
common cold by Drs. Jack M. Gwaltney and Federick G. Hayden
Cold
treatment and information by Drs. Gwaltney and Haden
NAID,
National Institute of Health: The common cold fact sheet
Dowling, H.F. 1958. Transmission of the common cold to volunteers under
controlled conditions. Am J of Hygiene 68:659-65.
Douglas RG Jr, Lindgren KM, Couch RB. 1968. Exposure to cold environment and
rhinovirus common cold: Failure to demonstrate effect. N Engl J Med
279:742-7.
(Answered Nov. 26, 2004)
