Fuat Bahadir
Omaha, Neb
THE AUTHORS REPLY: As to the first question, all known elementary particles—those that are in an energy range that allows us to observe them directly in particle accelerators—behave according to the rules of both quantum mechanics and four-dimensional space, so there is no contradiction here. The phenomenon of the change in the spectral dimension observed in the theory of causal dynamical triangulations happens on much shorter scales and crucially needs the input of both general relativity and quantum theory in a unified way. This unusual behavior will affect particles (matter) as well as the dynamical behavior of spacetime itself at these scales.
Regarding the second question, when we wrote about the “overall form” of space, we were referring to the way it “hangs together” as a whole (what a mathematician would call its topology). This approach still leaves the freedom for space to grow or shrink, to bend, deform or develop bumps in places, and so on, which indeed will depend on how the microscopic pieces fit together, appear and disappear. The important point is that three-dimensional space cannot break up into several pieces or develop additional handles to change its overall connectedness.
Beat and the Beast
I disagree with Steven Brown and Lawrence M. Parsons’s assertion in “The Neuroscience of Dance” that humans are the only species that can dance or display rhythm. Other species are quite capable of displaying rhythm. Horses performing dressage, for instance, are accompanied by music. And parrots and other birds move to music. (A simple Google search for “animal dancing” returns many videos of animals exhibiting rhythmic movement as well.) Although one can argue that these animals are displaying learned behaviors, they must have a predisposition for rhythmic movement.
Dennis Carrasquillo
via e-mai
THE AUTHORS REPLY: Our point on unique human rhythm capacity was not about synchronization per se but about the ability to entrain to an isochronous (steady) beat, as is typical in group dance and music. We are not aware of any evidence that nonhuman animals naturally show coordinated group movements to an isochronous beat. Since completing our article, however, two teams of colleagues (led by Aniruddh D. Patel of the Neurosciences Institute in San Diego and by Marc D. Hauser of Harvard University) have reported studies showing evidence that parrots, cockatoos and macaws can move in synchrony to a limited range of musical beats.
Thus, the ability of an individual to synchronize to an isochronous beat may not be limited to humans. Such a capacity in birds is latent, though, because in the wild they do not generate isochronous sounds and hence have no opportunity to entrain to beats. Research in this area is developing rapidly, so we will all need to stay tuned.
Note: This article was originally printed with the title, "Letters".
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8 Comments
Add CommentLouise Tremblay Cole is incorrect to imply in her letter Justifiable Herbicide? that herbicides all have the same known effect ... on humans, animals ... soil and groundwater . For one thing, those herbicides commonly used in no-till to replace the contribution of ploughing to weed control are distinctive in being inactivated and immobilised on contact with the soil.
Reply | Report Abuse | Link to thisSustainability inevitably involves trade-offs in seeking the balance between planet, people and profit. Trade-offs demand valuing some things more than others and assessing risks and benefits.
Ploughing requires considerable use of fuel and is a costly, time consuming operation. In those parts of the world where ploughing is done by animal power or spade work, it is an arduous, drudgerous job. Besides avoiding soil erosion, not ploughing also means that soil organic matter accumulates, so sequestering large amounts of carbon. For instance, the Soil Science Society of America recently estimated that wider adoption of conservation tillage in the US could off-set the annual release of more than 130 million tonnes of carbon dioxide.
Many people will surely never accept the arguments for using herbicides simply because they dont like the concept. Fair enough, but it makes sense to weigh-up the best practical ways currently available with which to farm each and every field, and to constantly look for improvements in all aspects. Lets keep discussing the issues, be passionate, but not over-emotional where it detracts from plotting the best course.
Ms. Cole's response falls within expected parameters for her standpoint. Sadly, she chooses to utilize invective as opposed to reason. I would simply ask if she has seen the clouds of dust that accompany a field being ploughed, has watched the wind strip the topsoil from a freshly turned field, and if she believes that this method of field preparation can be indefinitely continued without causing serious damage to the volume and quality of topsoil in the world's agricultural regions.
Reply | Report Abuse | Link to thisI believe that much of the concern I read here may be more related to chemical fertilizer runoff than herbicide runoff, as herbicides are generally more complex compounds that do degrade over time, with half-lives varying widely depending upon the specific compounds. Chemical fertilizers are longer-lasting by their very nature, as they tend to be more elemental in nature, so any runoff or groundwater infiltration will maintain much of the initial chemical potency included in the original formulations.
I will grant that the issue is complex, but to place a blanket condemnation on herbicide use is shortsighted, as advances are being made. Science should yield more efficient soluitions as time goes by. In the meantime, we must choose among the available options, with a mind toward conserving the topsoil that is truly the cradle of our agricultural life.
Neither you nor I has seen the "clouds of dust" that accompany a field being ploughed, nor have we seen wind strip topsoil from a freshly turned field as ploughing is virtually always done in early spring as soon as the soil has dried just sufficiently to allow tractor work, or in the fall to incorporate harvested crop residue for its organic properties.
Reply | Report Abuse | Link to thisCausaul dynamic triangulation is just a schematic way, by which the dense particle system, i.e. Aether condenses.
Reply | Report Abuse | Link to thishttp://aetherwavetheory.blogspot.com/2008/09/sacred-geometry-and-aether-concept.html
Hi,
Reply | Report Abuse | Link to thisi'm a person who is simply passionate about phy6. i like physics 4 its elegance n stuff.
i'm a phy6 student n would like 2 pursue my career in physics anyway!
i like 2 discuss physics particularly topics like quantum theory, relativity
and much more!
for interesting stuff visit:http://blog.myspace.com/index.cfm?fuseaction=blog.view&friendID=20019115&blogID=415638693 and http://blog.myspace.com/index.cfm?fuseaction=blog.view&friendID=20019115&blogID=436414231
Reply | Report Abuse | Link to thisAs a farmer, I suggest you grow your own food. then grow some extra to use a barter for shelter, fuel and a little more for movie tickets.
Reply | Report Abuse | Link to thisIdiots and idealists. Do me a favor. Starve.
I future, instead of useing herbicides we could go back to the labour work, but instead of labourers we will use robots, image the whole army of robots like from The Matrix, witch harvest our crops ;>
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