posted on Jul, 13 2016 @ 04:46 AM
Dark Matters
NEIL DEGRASSE TYSON·TUESDAY, JULY 12, 2016
Occasionally, I personalize dark matter’s place in the universe. Especially the part about matter and dark matter feeling one another’s gravity
but not otherwise interacting. Never was this more real to me than during the summer of 991, when I attended an annual conference near Atlanta,
Georgia, of a national physics society that I belonged to. That autumn I would begin my astrophysics postdoctoral research appointment at Princeton
University.
Conferences are comforting places. You feel as if you’ve known people your entire life even though you’ve never met because everyone’s life
path strongly resembles that of your own. Among professional physicists, for example, we all got good grades in school (last checked, physicists are
disproportionately represented among college seniors who graduate magna and summa cum laude). We’ve all solved the same homework problems in physics
classes. We’ve all read the same books. We wield nearly identical vocabulary sets when describing the physical world. And we’ve all felt the
occasional aspersions cast by pop-society on our intellectual abilities.
By the time of the society banquet, held the last night of the conference, people have loosened up. Discussions commonly shift to personal matters
and other things that have nothing to do with the subjects and themes of the conference. By the end of this particular banquet, a dozen of us from
several adjacent tables collected the unfinished bottles of wine and retreated to one of those common-rooms on the top floor of the hotel. We talked
(and argued) about the sorts of things that the rest of society would surely consider to be geeky and pointless, such as why cans of Diet Pepsi float
while cans of regular Pepsi sink. That one was new to me, although I did have latent memories from the end of long parties where all the ice had
melted in the beverage cooler and some soft drinks were floating while others were resting at the bottom.
We lamented the fact that the transporter in the television and film series Star Trek does not transport perfectly across spacetime. Apparently,
the teleported copy sustains an extremely small but quantifiable level of degradation when compared with the original—a perversely humorous fact
that was well-known among the Star Trek cognoscente. The questions to be debated started rolling: How many times could you be transported back and
forth between the starship and a planet before you started to look different? What part of your body would change? Was it your DNA? Was it your atomic
structure? Or would you one day beam back to the ship without a nose?
That night was rich in the expression of applied mental energy. What else could you have expected among intellectual soul-mates, at the end of a
full meal, near the end of a full conference, while sipping good wine into the late evening?
Around midnight, while discussing momentum-transfer in automobile accidents, one of us mentioned a time when the police stopped him while driving
his car. They ordered him from his sports car and conducted a thorough search of his body, the car’s cabin, and the trunk before sending him on his
way with a hefty ticket. The charge for stopping him? Driving twenty miles per hour over the local speed limit. Try as we did, we could not muster
sympathy for his case, although a brief discussion of the precision of police radar guns followed. We all agreed that on a straight road, the geometry
of a radar gun measurement prevents your exact speed from being measured unless the police officer stands in the middle of the oncoming traffic. If
the officer stands anywhere else, such as to the side of the road, the measured speed will be less than your actual speed. So if you were measured to
be speeding, you were certainly speeding.
My colleague had other encounters with the law that he shared later that night, but he started a chain reaction among us. One by one we each
recalled multiple incidents of being stopped by the police. None of the accounts were particularly violent or life-threatening, although it was easy
to extrapolate to highly publicized cases that were. One of my colleagues had been stopped for driving too slowly. He was admiring the local flora as
he drove through a New England town in the autumn. Another had been stopped because he was speeding, but only by five miles per hour. He was
questioned and then released without getting a ticket. Still another colleague had been stopped and questioned for jogging down the street late at
night.
As for me, I had a dozen different encounters to draw from. There was the time I was stopped late at night at an underpass on an empty road in New
Jersey for having changed lanes without signaling. The officer told me to get out of my car and questioned me for ten minutes around back with the
bright head lights of his squad car illuminating my face. Is this your car? Yes. Who is the woman in the passenger seat? My wife. Where are you coming
from? My parents house. Where are you going? Home. What do you do for a living? I am an astrophysicist at Princeton University. What’s in your
trunk? A spare tire, and a lot of other greasy junk. He went on to say that the “real reason” why he stopped me was because my car’s license
plates were much newer and shinier than the 17-year old Ford that I was driving. The officer was just making sure that neither the car nor the plates
were stolen.
In my other stories, I had been stopped by the police while transporting my home supply of physics textbooks into my newly assigned office in
graduate school. They had stopped me at the entrance to the physics building where they asked accusatory questions about what I was doing. This one
was complicated because a friend offered to drive me and my boxes to my office (I had not yet learned to drive). Her car was registered in her
father’s name. It was 11:30 PM. Open-topped boxes of graduate math and physics textbooks filled the trunk. And we were transporting them into the
building. I wonder how often that scenario shows up in police training tapes. In total, I was stopped two or three times by other security officers
while entering physics buildings, but was never stopped entering the campus gym.
In that conference hotel room, we exchanged stories about the police for two more hours before retiring to our respective hotel rooms. Being
mathematically literate, of course, we looked for “common denominators” among the stories. But we had all driven different cars—some were old,
others were new, some were undistinguished, others were high performance imports. Some police stops were in the daytime, others were at night. Taken
one-by-one, each encounter with the law could be explained as an isolated incident where, in modern times, we all must forfeit some freedoms to ensure
a safer society for us all.
To be cont...