Dr. Bortrum
09/11/2008
Collisions, Small and Humongous
First a brief update on Old Bortrum’s continuing battle with communications technology and mastering the new StocksandNews format and posting regime. Without going into detail, and without really understanding the reasons, I can now post my column without the need to delete the five or so extra columns that pestered me earlier. I also managed to get a new e-mail address by making my first call ever to a tech service person in the entire time I’ve had a computer, some 20 years I imagine. Should I be proud of myself or is it simply a case of a typical male not wanting to ask for directions?
As mentioned before, I switched recently from a telephone company, Verizon, to my cable company in one of those all-inclusive phone-cable-Internet packages. When I switched, the cable company representative assured me that they would notify Verizon of the switch. You can imagine my surprise when not only did I receive a bill from Verizon which was larger than my usual bill but also got a letter from an officer of Verizon welcoming me and thanking me for choosing Verizon as my domestic and long-distance carrier! Obviously, not what I expected. A call to Verizon and I was reassured to hear that they had already recalculated my bill and were aware of the cancellation.
I also have noted how wonderful the HDTV picture was after installation of a new cable midway through the Beijing Olympics. Well, about a week ago our TV began to "stutter" on a random but frequent basis. Words would be lost and the picture would briefly disintegrate. A call to the cable company and the woman who responded asked me to pull the cable box power cord from the electrical outlet. I did as told and after a brief period of time she said plug it back in. The problem was solved. I was amazed, thinking she had sent some magic signal to the box. However, my computer gurus opined that what I had done was essentially reboot the cable box, just as I reboot my PC. Just another tip for those rare, if any, readers who are as ignorant as I am about modern communications technology.
Our editor Brian Trumbore often stops by to drop off various news items of possible interest for a column. The items are sometimes quite wide ranging as, for example, last week’s two items from BBC News. One, dated August 30, was a report by Paul Rincon headlined "Cosmic crash unmasks dark matter"; the other, dated August 28, by Matt McGrath was headlined "Fly’s brain ‘senses swat threat’". When I was younger, I considered myself an expert at catching flies with my bare hands. However, in my advancing years my prowess in this area has declined significantly and I now don’t even try the bare handed approach but resort immediately to the fly swatter. McGrath’s report deals with the work of Michael Dickinson of the California Institute of Technology (Caltech). A visit to the Caltech Web site revealed further details of Dickinson’s work with graduate student Gwyneth Card on the problem of why flies are so hard to swat.
Based upon high-resolution, high-speed digital photography, the researchers think they have the answer, based upon the actions of fruit flies when faced with an imminent swat.
What they’ve found is that the fly’s tiny brain is capable of detecting the presence of the swatter and, within a tenth of a second, calculates its route of escape and adjust its body into an optimal position to avoid the swat. The fly is able to sense a threat from almost any direction since it can see in back of itself as well as in front and to the sides.
Say the fly sees a swatter coming from the front. The photos show that the fly moves its middle legs forward and also leans back, following which it extends its legs to push off backward. If the swatter comes from the back, the middle legs are moved back in preparation for a forward leap. If swatting is coming from the side, the middle legs stay put but the whole body leans away from the impending swat. The swiftness of the fly’s reactions indicate a surprisingly sophisticated brain that seems as though it has a map that helps convert the direction of the imminent swat into motor actions resulting in the right pattern for quick takeoff. The researchers hope to find out which part of the brain accomplishes this feat. I’m impressed that they can even find the brain in this small insect.
How to properly swat a fly? Approach the fly stealthily; the fly has a problem detecting slow movement. If you’re swatting from behind the fly, try to outwit it by aiming a bit in front of its anticipated forward path. Hey, with this new knowledge, we humans should be able to get that pesky fly every time.
This is a huge week for the world of physics, with the first batches of protons circling the 17-mile underground tunnel of the Large Hadron Collider (LHC) in Switzerland. The media have highlighted the event, giving publicity to the fellow that sued to stop the LHC from being turned on in the hopefully unfounded belief that small black holes would be created that would gobble up our Earth! If you saw the reports on the TV shows, you have some idea of the hugeness and the complexity of the machine. One hope for the LHC when it gets fully operational is that we might learn more about the nature of dark matter, which comprises some 23 percent of our universe.
Dark matter is at the heart of the BBC report by Paul Rincon and a press release on the Web site of the University of California, Santa Barbara (UCSB). On a slightly larger scale than the collision between a swatter and a fly, two collisions of clusters of galaxies have confirmed the weirdness of dark matter. Aside from its gravitational effects, dark matter, whatever it is, doesn’t seem to interact with anything, even with other dark matter. One of the collisions of galaxy clusters, known as the Bullet Cluster, was discovered in 2006 ,while the more recently discovered cluster, announced on August 27 by NASA, has no catchy name as yet and is known simply as MACSJ0025. This latest collision was discovered using both the Hubble Space Telescope and the Chandra X-ray Observatory. Aside from just the fact that these huge collisions of galaxy clusters involve amounts of material a quadrillion times the mass of our Sun, why all the fuss?
One answer is that the newly discovered collision confirms the dark matter findings for the Bullet Cluster. Through the use of gravitational lensing, which includes the bending or distortion of light by dark matter, the international team of researchers, led by Marusa Bradac of UCSB, were able to separate the dark matter from the ordinary matter. The ordinary matter, The ordinary matter, mostly hot gas, glows brightly in the X-ray region detected by Chandra.
The picture I found on the UCSB Web site combines the Hubble and Chandra images with the gravitational lensing calculations. It shows a ordinary matter clumped together in the central region with dark matter extending out from the central region on both sides. The conclusion is that the collision of the galaxy clusters, each with about a million billion times the mass of the Sun, resulted in the gases colliding and slowing down as you would expect as they bump into each other. However, the dark matter in the clusters essentially was unaffected in the collision but just kept sailing along; hence the separation of the dark matter from ordinary matter.
To illustrate, let’s pretend we have two clusters in which we represent the ordinary matter by "o" and dark matter by either "d" or "D" (to distinguish the dark matter in the two galaxy clusters. So, we have the clusters dddddoodddd and DDDDDooDDDDD (there’s about five times more dark matter than ordinary matter in the universe). If the two clusters collide on a line, the result is crudely DDDDDDDDDDoooodddddddddd. The d and D dark matter just kept going while the o ordinary matter slowed down. I don’t know if this helps or not to understand, or if I understand, but hey, it’s the best I can do.
Seven years ago today there were, sadly, collisions of a different sort and I would be remiss if I did not acknowledge that today is the seventh anniversary of 9/11, a day that will never be forgotten by those of us in the metropolitan New York area. People are still suffering, and dying, from medical problems initiated when responding or working in or around Ground Zero. For a personal perspective at the time of the event, see my column of 9/18/2001.
Allen F. Bortrum
