YSM Issue 86.4

everyday Q&A
Q&A
Almost everyone has struggled with jet lag, but what are the actual causes behind it?
After flying halfway around the
world, even the most seasoned
traveler will succumb to drowsiness,
disorientation, and a strong
urge to fall asleep in the middle of
the day. As we struggle to adjust
to new time zones, we cannot
help but experience the sensation
known as jet lag — the sun in our
new location tells us what time of
day it is, but our brains often do
not process the switch for several
days.
Normally, the body’s internal
clock is programmed to respond
to light as a stimulus that keeps
us alert and awake. But when the
body suddenly shifts to a different time zone, something occurs
at the molecular level that prevents light from having its immediate
effect. This “something,” recently discovered by a group of
Q&A
What Causes Jet Lag?
In high school chemistry class, we learned that absolute zero is
exactly what its name suggests: the lowest possible temperature
that can exist, the threshold at which atoms lose all their kinetic
energy and stop moving. However, physicists recently created
an atomic gas that exists below this threshold, or at negative
temperatures.
The term “negative” is actually a bit misleading. “The gas is
not colder than zero Kelvin, but hotter,” explained Dr. Ulrich
Schneider, the lead physicist of the project. “It is even hotter
than at any positive temperature — the temperature scale simply
does not end at infinity but jumps to negative values instead.”
To explain the idea of negative temperature, the researchers
describe their system in terms of hills and valleys. At absolute
zero, atoms have no energy, and they are all at the bottom of
the valley. As temperatures increase, some particles gain enough
energy to move up the hill, but most remain at the bottom.
A temperature of exactly infinity is the balancing point. Here,
enough particles have left the valley and spread out evenly along
the hill’s slope. But past infinity, more particles are on the hill
than in the valley — the exact opposite of the distribution in the
positive temperature realm; this is what physicists call negative
temperature.
In their experiment, the researchers forced a gas into its
highest possible energy state, achieving a temperature of a few
BY MARIANA DO CARMO
IMAGE COURTESY OF SCRIPPS COLLEGE
Researchers at Oxford University have found that a protein
called SIK1 is at contributor to symptoms of jet lag.
researchers at Oxford University,
is actually a protein called
salt inducible kinase 1, or SIK1.
The protein acts as a “molecular
brake” on the effect of light
in the human body, inhibiting
certain genes in our DNA that
are activated by light and that
help the body adjust to different
time zones.
By reducing SIK1 activity in
mice, the research team found
that animals acclimated to time
zone changes in only a few
hours, whereas untreated mice
required six days to adjust. This
newfound understanding of the
molecular basis behind jet lag may lead to drugs that could help
minimize SIK1’s effect on humans — and maybe help us all enjoy
the first few days of travel a bit more.
Can Temperatures Ever Drop Below Absolute Zero?
Physicists can now push temperatures below what has been considered the lowest energy minimum.
BY AHMED ANSARI
IMAGE COURTESY OF LMU/MPQ MUICH
Scientists were able to reverse the distribution of atoms
at positive temperatures (blue), resulting in a negative temperature
system (red).
billionths of a Kelvin below absolute zero. Their work opens
up possibilities for the study of other high-energy systems that
would otherwise collapse.
2 Yale Scientific Magazine | November 2013 www.yalescientific.org