Is the planck length a commonly accepted theory or is it controversial in any way?
It is a length, mee. It is not a theory at all---controversial or otherwise!mee said:Is the planck length a commonly accepted theory or is it controversial in any way?
this is praiseworthy speculation. but I dont yet believe the "smallest measureable/meaningful" stuff so i cant help you speculate.mee said:What I was referring to is that in some popular science, the planck length is referred to as the smallest measureable distance: that distance below this amount would have no meaning in the classical sense. I was asking as to its relativity to geometry. If the planck length is the smallest measureable distance, and that distance smaller than this would have no meaning, then any line between two points perhaps has a finite number of points between the end points, measured in planck length units, each "point" becoming a unit one planck length in size.
Would not a line be curved if it was the shortest distance between two points in a curved space? Why would length have no meaning if a surface must be represented as at least a 2d object?arivero said:mee, besides Marcus' proposals, let me to add that most quantum gravitation theories (including, if you wish, strings) work at the level of surfaces and volumes, so the quantisation of the measurement of a lenght is beyond reach. This is not so strange if you think that curvature, the main quantity of gravitation theory, is defined for surfaces.
there was a post from Baez on SPR that gave other reasoning, nevertheless in line with what you say here. I forget the exact detail but he gave different indications that area might be somehow more basic than length---the unit of length would then be just the square root of the area unit.arivero said:mee, besides Marcus' proposals, let me to add that most quantum gravitation theories (including, if you wish, strings) work at the level of surfaces and volumes, so the quantisation of the measurement of a lenght is beyond reach. This is not so strange if you think that curvature, the main quantity of gravitation theory, is defined for surfaces.
And why I would point back to emergent realities for consideration.To describe extra dimensions that would affect gravity alone, the Stanford-Trieste researchers made use of entities known as branes. Those complex, membranous objects, which can have many spatial dimensions themselves, have become a central part of string theory. In some versions of the theory, the universe itself is a brane with three spatial dimensions—a 3-brane—moving through a higher-dimensional space-time.
String theory dictates that any extra dimensions outside a brane affect only gravity. In other words, just the force-carrying particles of gravity, called gravitons, could travel in the space-time beyond the brane, leaving the other forces confined to the brane. By contrast, extra dimensions associated with the brane influence all the forces.
Therefore, even if gravity boasts an intrinsic strength similar to that of the other three forces, because it diffuses throughout the external space-time, also called the bulk, its apparent strength in the 3-brane universe is much reduced.
Any extra dimensions affecting gravity would alter Isaac Newton's inverse-square law, which holds that objects attract each other with a force inversely proportional to the square of the distance between them. The theorists calculated that one extra dimension in the bulk would have a scale of 100 million kilometers—about the distance from Earth to the sun. That option isn't feasible because Earth's orbit obeys the inverse-square law.
then the average size of a string should be somewhere near the length scale of quantum gravity, called the Planck length, which is about 10-33 centimeters, or about a millionth of a billionth of a billionth of a billionth of a centimeter. Unfortunately, this means that strings are way too small to see by current or expected particle physics technology (or financing!!) and so string theorists must devise more clever methods to test the theory than just looking for little strings in particle experiments.
Indulge me, as the bald guy in "Contact" said.
Would someone please calculate c4/G
So what about the Planck force unit? How big is it?
Great. Four years later somebody responded and calculated the Planck unit of force.... I find:
c^4/G = 1.210565719x10^44 newtons
Hi Don,The L4 value is 2pi times the photon sphere radius for the electron mass so its value is (2pi) (3Gm/c^2).
Hi Arivero,Hi Don,
Do you have a source for this name, "photon sphere radius", or is it your nomenclature? .