An interesting article at Phys.Org describes a new discovery near the center of the Milky Way.
An unprecedented new telescope image of the Milky Way galaxy's turbulent center has revealed nearly 1,000 mysterious strands, inexplicably dangling in space.Stretching up to 150 light years long, the one-dimensional strands (or filaments) are found in pairs and clusters, often stacked equally spaced, side by side like strings on a harp. Using observations at radio wavelengths, Northwestern University's Farhad Yusef-Zadeh discovered the highly organized, magnetic filaments in the early 1980s. The mystifying filaments, he found, comprise cosmic ray electrons gyrating the magnetic field at close to the speed of light. But their origin has remained an unsolved mystery ever since.
Lines are always one-dimensional - dots are zero-dimensional. (A cube is three dimensions and a flat plane is two.)
ReplyDeletea dot is 0D, a line is 1D (e.g. just x), a plane (like a piece of paper) is 2D (x and y), a cube is 3D ( x and y and z)
ReplyDeleteHTH
A point has "zero" dimensions. A line has one, and a plane has two. It might help to think of the dimensions as the axes of motion (x, y, and z) with the six degrees of freedom representing rotational and translational motion around or along each axis.
ReplyDeleteThanks to all. Clearly I misremembered my eighth-grade math. But... if a line only has length, but no width, how can it be visible. Presumably the visibility is an artifact of the representation? So that a line that I draw with a pencil does have two (or three) dimensions, but a mathematical line just has one because it is a concept only, not a "thing."
ReplyDeleteBut if my previous comment is true, then the "strands" that the telescope is "seeing" must have a width, and should be described as two-dimensional?
DeleteSpeaking as an English major...
The lines may be generating some sort of force field at a fairly small radius around the length of whatever the line is, akin to the magnetic field around a cuŕrent-carrying wire.
ReplyDeleteThey look to twist and turn through three axes to me. I'm not sure how this is different from any other three-dimensional object.
ReplyDeleteNo doubt the strands are actually 3D, but are effectively 1D because their widths and depths and very much less than their lengths, just like a pencil line. Something that is truly 1D (or even 2D) is a mathematical construct.
ReplyDeleteI suppose when something is 150 LIGHT-YEARS long, it becomes "effectively" one-dimensional.
DeleteOr perhaps viewing the universe as having three dimensions is a particularly human deficiency.
So would a wormhole be 1D or 3D?
ReplyDeleteBelieve it or not, JUST TODAY I was watching a Khan Academy video set on geometry (I'm a teacher, but I have to refresh (and learn!) every so often. On the video, it said that a POINT on a plane had ZERO dimensions. I had always understood it to have ONE. But, nope. A line, however, in that it moves in a single direction (i.e., ONLY left or right, say) is ONE dimensional. A set of lines that go in two directions are, yep, two dimensional. But now that we have left/right, up/down, we add in depth, and we are now 3D.
ReplyDeleteLooks like BOTH of us learned something today!
I vaguely remember reading some book about a two dimensional world...
ReplyDeletehttps://en.wikipedia.org/wiki/Flatland
DeleteReading this short book will give one a very complete understanding of (at least the first four) dimensions and how they relate to one another in the (3-D) world. Highly highly recommended. "Flatland" by Edwin Abbott Abbott, with a name like that of course he is a British schoolmaster, first published in 1884 - don't be scared, crack this book!
Deletethe way physicists use the term dimensionality is all about degrees of freedom - not actual sizes. 1D means you (whatever "you" is in this case - magnetic particles? I am not an astrophysicist so no idea...) are only free to travel along the wire and cannot escape perpendicularly to it i.e. the particle is confined perpendicularly to the wire. The wire can kink and explore a 3D space but still be 1D from the confinement point of view ...
ReplyDeleteMaybe i need to read things more carefully in my old age, but that image sure looks like today's APOD:
ReplyDeletehttps://apod.nasa.gov/apod/ap220202.html