Hi. I am not a physicist or a mathematician, but I am a Professional Licensed Electrical Engineer with a Masters Degree in EE. I did get through the Quantum Physics class but never pursued the theoretical sciences any further. I say all of this because I have come up with some rather odd ideas regarding the extra dimensions that are required for super string theory. I don’t want people to think I’m a crackpot or a joker. Given enough time I could solve complex differential equations with the best of them. So here goes. Currently there are three spatial dimensions that we are all familiar with, those defined by the x-, y-, and z-axes. They all measure displacement or magnitude from the origin. The units are feet, meters, Angstroms, or whatever. That unit is an elemental unit; it is not a combination of other units. The other dimension that is currently well documented is time. Again, time is a measure of magnitude from some origin. The units are seconds, hours, days, or whatever. Again, the unit is elemental. So, we’ve got 4 dimensions and we need 11. That means there are 7 more to find. How about that for complex math? It’s the toughest that I’ll be getting into in this post. This got me thinking about what the other dimensions were. Mathematics tells us that they must be orthogonal to one another. In mathematics, that means that they are perpendicular to each other. So, I guess that we have proven to ourselves that time is orthogonal to the 3 spatial dimensions. I don’t know how this is proven but I’ll take it as true. What that means to me is that time is unrelated to the 3 spatial dimensions. They don’t share anything in common. Their units are not related or intermingled. So, do the other dimensions have elemental units? I looked on the Internet and found that there are seven such elemental or basic units of measure; Length, Mass, Time, Electrical Current, Temperature (in Kelvin), Mole (the basic unit of substance. It is the amount of substance that contains as many elementary units as there are atoms in 0.012 kg of carbon-12. ), and Candela (the basic unit of luminous intensity. It is the intensity of a source of light of a specified frequency, which gives a specified amount of power in a given direction). All of the currently understood dimensions are covered under Length (3 dimensional space) and Time. Could the rest be 5 of the missing dimensions? If so what are the other two dimensions? If we assume that Mass (in Kg), Electrical Current (in Amps), Temperature (in Kelvin), Mole (in moles), and Candela (in Candela) are dimensions, do they meet the orthogonality criterion? At first glance they all seem to be unrelated to one another, or do they? I see Moles as another form of Mass (or is it the other way around?). I also see Temperature as a side effect of heat (the intensity of heat), which is part of the electro-magnetic radiation spectrum of light. Light intensity is measured by Candela. So, maybe we have found 3 of the missing 7 dimensions; and they are Mass (because it’s too hard to think of moles and there is a simple conversion factor between the two), Electrical Current, and Candela. Now we need to find 4 more dimensions. Well, what do these new dimensions have in common? Mass is a measure of how much of something there is. On Earth it is related to weight in the English units (pound mass). So, in simplistic terms, it is a measure of how much something weighs on Earth. Electrical Current is a measure of how many charged particles are traveling in an electric circuit. Candela is a measure of how intense a light source is. These are all perceivable by the human body. In the instance of the Electrical Current, you could put your body somewhere in the circuit by touching two points of it and the charged particles might flow through you. This particular experiment is not recommended. It’s better to put an Ammeter in place of your body to measure the current. The original 4 dimensions (3 dimensional space and time) are also perceivable by the human body. We can understand the concepts of physical displacement and of the passing of time. Maybe all of the dimensions are physically perceivable. What can we perceive? What are our senses? We have the sense of sight, hearing, smell, taste, and touch. Some say Extra Sensory Perception (ESP) is the sixth sense, but this is debatable, so I’ll leave it out. Sight has already been covered because our eyes measure the intensity of light at different wavelengths. Our sense of hearing is our ability to discern audio pressure waves through the air at different frequencies. It is measured in Decibels. If ever there was a misunderstood unit, this is it. Part of the problem is that it is not a unit at all. The definition of a decibel is that it measures the relative difference in power (acoustic or electric) equal to 10 times the common logarithm of the ratio of the two power levels. It is actually unit less; you divide power by power (making it unit less) then take the common log (a unit less operation) then multiply by 10. But we do know that small values of decibels are quiet and large levels of decibels are loud. Again this is a measure of the magnitude of something that has been common to all of the previous dimensions. So, if sound is a dimension then we only have 3 more to find. Next is Smell. I can hear it already; Smell is a dimension? He’s nuts. Well it does fit the criterion that we have set up. It is discernable. I could also imagine that it has an elemental unit. I couldn’t find one on the Internet, but I’m sure that some French perfume designer has some sort of unit for it, however obscure. If someone can tell me what it is I’ll be grateful. I think it has something to do with the frequency at which our smell receptors oscillate in the presence of different chemicals that have odor. So then there were two. One of the remaining dimensions could be taste. Taste is similar to smell but the nerves are in the tongue instead of the nose. Most of what we perceive as taste is really smell. Our tongues can only discern 4 different true tastes; sweet, salty, sour, and bitter. So, I would bet that taste again has something to do with tickling our taste buds at a certain frequency, which tells our brain that something tastes salty or sweet or bitter or sour. Lastly we touch on the sense of touch. What is that all about? I think that primarily it has to do with the “grittyness” of a surface. Things are either smooth or rough and there are varying degrees of smoothness. Think of sandpaper. It has a numerical smoothness called grit. Sixty grit sandpaper is very rough, 600 grit is very smooth (as sandpaper goes). Glass might have a grit value of several thousand. It seems that it has to do with the number of particles of sand per unit of measure (like per inch). More particles per inch means that they all must be smaller in order to fit them in. Therefore the end product is smoother as the number increases. I do have a problem with using grit as a dimension because of that “particles per inch” unit. That means that it is related to some other unit; length. There is another way to characterize grittyness; that is friction. There is a constant used in the friction equations called mu. Mu is defined as the tangent of the angle at which something starts to slide on itself. That is, suppose we took two blocks of wood and covered them both with 200 “grit” sandpaper. Then we place one on top of the other and put that stack on a table. Then we pick up one edge of the stack so that the whole thing starts to tilt to one side. We could measure the angle of the tilt and determine the angle at which one block starts to slide off of the other. Then we take the tangent of that angle and we would have the constant mu for 200 grit sandpaper. So maybe grittyness measured by mu is the final dimension. Maybe all of this is also complete hogwash. I don’t know. But Einstein did prefer a simple, elegant solution to the mysteries of the universe. Something in my head tells me that this is more believable than 10 dimensional space plus time. Maybe everything is defined by how big it is dimensionally, where it exists in time, how much it weighs, how well it conducts electricity, how much light it reflects or emits, what it sounds like, what it smells like, what it tastes like (another experiment that is not always recommended) and how gritty it is. Please comment.