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06/21/2006
Head-on Encounters
My last column was posted the day after 6/6/06 and I remarked
about awakening at 6:06 AM that day. Last week, as part of a 6-
day trip, I attended my 60th reunion at Dickinson College in
Carlisle, Pennsylvania. Sure enough, there were 6 of us from the
class of 1946. After the reunion, we traveled to Greensburg and
Arnold Palmer country for a pleasant visit with my wife’s family.
On the return trip, all those sixes tried to wield their devilish
influence. Exiting the Pennsylvania Turnpike in Carlisle, I found
myself at the extreme right tollbooth. The off ramp to connect
with Interstate 81 is in line with the extreme left tollbooth.
Hence, I had to cross, looking to the left, to avoid the heavy
Carlisle traffic exiting on the right.
I deftly cleared those vehicles and was on the exit ramp. Or so I
thought. I’m sure the truck driver who found me facing him as
he entered the Turnpike area was just as surprised as I was to see
him. I had somehow gone one too many lanes over and was on
the entrance ramp! Fortunately, I had only traversed a hundred
feet onto the ramp. Not a great backer upper, I did manage to
back up and get on the proper exit. I’m sure my wife won’t
allow me to forget my blunder and any future criticism of her
driving will be met with disdain.
But there was more; five minutes after leaving the Turnpike, I
was on the ramp to Route 81 where extremely heavy truck traffic
made it impossible to merge. I was going very slowly, awaiting
an opening, when a truck with a long flatbed passed and cut me
off, exiting the highway. We missed each other by millimeters!
The next time we head for Pennsylvania, we’ll consider flying!
But enough of my scary travels, let’s consider another type of
travel. A current movie, “The Lake House”, deals with a couple
trying to get together but one of them is living two years in the
past. Time travel is the stuff of science fiction and, while I’m
certain we’ll never be able to travel into the future, we do have
ways of traveling into the past. One way is history. We have
books, cave drawings, photographs, pyramids, etc. and with
movies, TV tapes, DVDs and the like, we can even see the past
unfold “live” so to speak. With their telescopes, astronomers can
observe events happening “live” that took place, depending on
how distant the object, years or even billions of years ago.
But what if we want to travel back in time to less than a second
after our universe was born? Remarkably, it appears we have
done just that. In a column posted from Marco Island dated
3/21/2000, I wrote about a project at Brookhaven National
Laboratory. The goal was to recreate the primordial “soup”
generated in the very first second of the Big Bang. (Incidentally,
that was a strange column, dealing with sex in an MRI machine,
red tide and migraine headaches in addition to the Brookhaven
project. Had the red tide on Marco Island affected old Bortrum?)
Well, the Brookhaven scientists reached their goal, as detailed in
an article by Michael Riordan and William Zajc in the May issue
of Scientific American. Let’s see how they’ve transported us
back to about a mere microsecond, that’s a millionth of a second,
after the Big Bang. In the past we’ve talked about fundamental
particles and what stuff is made of. Let’s take hydrogen, the
simplest element. An atom of hydrogen is a proton with an
electron circling it – a simplistic picture. The electron is a
fundamental particle and, so far as I know, it’s not composed of
any simpler particles. The proton is different. It was a
fundamental particle 60 years ago when I was at Dickinson
College, as was the neutron. Now we know that protons and
neutrons are actually composed of more fundamental particles
known as quarks and gluons. Gluons are particles that, like glue,
hold quarks together in the proton and neutron. The gluons do
such a good job that we’ve never seen a lone, single quark.
However, there was a time when quarks and gluons roamed free.
This happened a ridiculously teensy fraction of a second after the
birth of our universe in the Big Bang. The temperature was a
toasty 10 quadrillion degrees Centigrade. This didn’t last long.
After only 10 microseconds, the temperature fell to 2 trillion
degrees and the gluons grabbed quarks together, combining them
to form protons and neutrons. Only about 2 minutes later, with
temperatures of a billion degrees, protons and, I presume,
neutrons, combined to form helium and other elements. It was
too hot for these elements to hang on to electrons circling their
nuclei. These were ions. It was only about 380,000 years later
that temperatures had fallen to a cool 2700 degrees and neutral
atoms of the type we know and love first formed.
How did the Brookhaven researchers propose to travel back in
time to less than a second after the birth of our universe? They
would create the conditions of those first few microseconds when
the quarks and gluons roamed free. They didn’t expect to be able
to actually “see” individual quarks but, with fantastic detectors
and super computers, they would trace the paths of the myriad
particles that form when quarks and gluons get together.
The name of the game in nuclear experiments is ENERGY.
Let’s take the example of my blunder on the ramp. If that truck
hadn’t stopped and hit me there would have been a lot of energy
expended. But even more energy would be expended if we both
had been moving and hit each other. A head-on collision is the
ultimate. The Brookhaven workers would crash nuclei of gold
racing at 99.99 percent of the speed of light together in head-on
collisions. They hoped that the energy in these collisions would
be so great that it would tear apart the gold nuclei and create,
ever so briefly, the free quark-gluon mixture that existed from
about 1 to 10 microseconds after the Big Bang.
It worked. These head-on collisions produced microscopic
fireballs at temperatures of trillions of degrees. Protons and
neutrons literally melted, freeing the quarks and gluons, but only
for about 50 trillionths of a trillionth of a second! The quarks
and gluons recombined to form particles that explode outward
into the detectors. Detecting and tracking these thousands of
particles is a daunting that the international Brookhaven teams
have succeeded in accomplishing. These teams have involved
anywhere from 60 to 500 scientists.
When I said the goal was to create a primordial “soup”, the
prevailing view was actually that the quarks and gluons would
act like a gas, according to the Scientific American article.
Surprisingly, it seems that “soup” is more appropriate. The data
indicate the free quarks and gluons behave like a liquid with
hardly any viscosity. In other words, it’s possibly the most
perfect liquid ever seen.
To generate the head-on collisions, the workers used two beams
of gold nuclei in roughly circular tunnels more than 2 miles long
with the beams colliding head-on in four separate locations. Each
location had its own specific types of detectors designed to
measure different aspects of the collisions. To guide the beams
of gold nuclei there were two strings of 870 superconducting
magnets cooled by tons of liquid helium! Earlier, workers at
CERN in Switzerland had obtained whiffs of quark-gluon
mixtures corresponding to about 10 microseconds ABB (after
Big Bang). Brookhaven has taken us to near 1 microsecond. A
more powerful machine in Europe will crash nuclei of lead.
If crashing two gold nuclei is like crashing two Volkswagens,
crashing the heavy lead nuclei should be like crashing two
tractor-trailers, I imagine. The huge energy released should take
us back to a few tenths of a microsecond ABB. Even with old
Bortrum’s obsession about our roots, that’s far enough for me!
Allen F. Bortrum
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