tag:blogger.com,1999:blog-808697756426649418.post3214069288897964140..comments2023-12-25T09:58:54.563-06:00Comments on The Christian Freethinker: Apparent Absurdities in Modern PhysicsMark Hausamhttp://www.blogger.com/profile/07371790103414979060noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-808697756426649418.post-88602736415759676082014-12-02T11:50:07.306-06:002014-12-02T11:50:07.306-06:00"A meter stick traveling near the speed of li..."A meter stick traveling near the speed of light is a meter long from the meter stick's perspective, but it's less than a meter long from the perspective of a stationary observer. Both are literally true at the same time, not optical illusions."<br /><br />I'm not sure what this means as a description of physical reality. I need to give it some more thought before saying anything.<br /><br />"And according to general relativity, light moving in a straight line past a massive object travels farther than light moving in a straight line without the massive object."<br /><br />Taken straightforwardly, in terms of what the words seem to mean, this sounds problematic. If light is traveling in a straight line, in a literal sense, it has to go a certain distance, and if it goes that distance, it goes that distance. If light travels one mile, then it travels one mile. It cannot travel one mile and 1/2 mile at the same time, for then it would end up in two different places at once. If I walk a mile in a straight line, it cannot also be true that I've walked only a half mile in a straight line, for a half-mile away and a mile away are two different locations. We would have to say that I ended up a half a mile away from myself, which makes no sense. I suppose the same issue would apply to the meter stick as well. It must be a certain length, because one end must be a certain distance from the other end. If it is a meter and also only half a meter, one end of it would be in two different places at the same time.<br /><br />But certainly distances can appear differently to different observers in various ways, so perhaps there is a sensible understanding of this phenomenon. I'm not sure. What do you think?Mark Hausamhttps://www.blogger.com/profile/07371790103414979060noreply@blogger.comtag:blogger.com,1999:blog-808697756426649418.post-77463794498705051062014-11-07T23:17:58.445-06:002014-11-07T23:17:58.445-06:00Hi Raymond. Thanks for your very helpful comments...Hi Raymond. Thanks for your very helpful comments. I think what I hear you saying, at least with regard to "point particles" and possibly the nature of the "strings" of string theory, is that physicists use mathematically over-precise (for lack of a better word) descriptions of physical realities, and sometimes forget that the mathematical description is an approximation. For example, it is convenient in math to think of a particle as a point, even though a point cannot literally exist in the world, but physicists sometimes keep talking about particles as points even when they move into descriptions of the physical world. If I've understood you correctly, I think that makes a lot of sense. I can see how that kind of thing could easily happen.<br /><br />With regard to "curled up" dimensions, even if we say that the language of being "curled up" is not literal, we still have to deal with the idea of there being nine dimensions and six of them being "very small." Dimensions are nothing but spatial directions, and directions cannot be large or small. They are not physical objects. It is like saying that "up" is very little, or very big. This makes as much sense as saying that pi is bouncy, or that 2+2=4 sounds scratchy. It's blatant category confusion.<br /><br />But, I suspect that there are valid mathematical formulations underlying this language that work mathematically, and for some reason physicists have taken to using the language of "dimensions" to talk about them, even though they are not really a description of more than three literal dimensions in the physical world. Speaking literally, there cannot be more than three dimensions, because there simply aren't any other directions in space besides the three (and mixings of the three). This is evident from observation. But probably there are aspects of reality that can be mapped mathematically that are behind that language, and it is simply the language itself that is confusing in that it uses terms that originally meant something else and gives them a specialized meaning that is not adequately explained.Mark Hausamhttps://www.blogger.com/profile/07371790103414979060noreply@blogger.comtag:blogger.com,1999:blog-808697756426649418.post-19887005613523668952014-11-07T20:58:13.116-06:002014-11-07T20:58:13.116-06:00I'm a first year physics graduate student; I a...I'm a first year physics graduate student; I am very, very busy but I can offer some brief, drive-by comments that might also be helpful. I think you're correct there is something being lost in translation, although I don't want to pretend that all physicists are philosophically aware of their statements. For those who are (as some of my professors), I think one way to understand their statements on the connection of math to reality is that the real objects behave to some approximation as the math dictates. Thus for point particles, the real particles behave like mathematical point particles (to some approximation). Point particles have long been known to be problematic even mathematically though (look into the self-energy of an electron). This point of view might be held for strings too, but I don't know enough about string theory to safely say.<br /><br />This point of view on point particles (and strings) seems to be within Smolin's quotation itself: "Rather than behaving like mathematical points, they behaved more like stretched, one dimensional objects, something like rubber bands."<br /><br />It is common for even physicists who are philosophically aware to move smoothly and without warning between the mathematical model and the actual objects, so that literal reality is attributed to the mathematical objects. This can be confusing at times, even for physicists. I myself sometimes forget that the particles we are dealing with are not literally mathematical points (thanks for the reminder in this blog post!). Such is one of the limitations of the scientific method, I guess, in which we can only go by how the objects seem to behave as determined by empirical observation.<br /><br />As for curled up dimensions, I don't know string theory so I can't say for sure, but just going by the quotation, it seems to me the dimensions are not literally "curled." Rather, it seems they mean that the universe in the directions of those dimensions is extremely small: "the diameter of the universe in these directions is not much more than a Planck length." I don't know why they call it "curled" though; it is perhaps an artifact of the mathematical process that has the end result of making the equations describe a universe that is small in those directions. Perhaps the "curled" or "rolled" up means the universe "folds" in on itself in those directions so that its diameter is extremely tiny in those directions. But again, I don't know enough string theory.Raymondnoreply@blogger.com