Many physicists believe that there are over three spatial dimensions, but they can't understand why these extra dimensions can't be perceived or measured. Here are two theories attempting to explain why: 1. The "extra dimensions" are not stackable, therefore their value is 1 quant. Assume that there are a total of six spatial dimensions. Therefore, the dimensional values for the smallest possible subatomic particle would be 1q,1q,1q,1q,1q,1q( q referring to quant, which is the smallest distance of space). If these particles can stack themselves in only the first three dimensions, they would create a three dimensional world even though they are six dimensional particles. Humans would find it easy to understand complex physical structures since they are three dimensional. But if these structures are broken down into subatomic particles, suddenly three more dimensions would appear that would have to be taken into consideration in scientific formulas. This can explain the difficulting in merging classical physics with quantum physics. 2. The extra dimensions have a fixed and constant value that never changes. For sake of argument, let's assume that there are four spatial dimensions. The first three can have any value, but the fourth always has a value of 1 meter. Everything in the universe would be 1 meter tall in the fourth dimension, including the universe itself. Because the human brain perceives things based on differences(different colors, sizes, shapes, etc.), the brain wouldn't be able to perceive the fourth dimension even though it is everywhere. The only place this dimension would show itself would be in scientific formulas as some kind of constant. For all we know, the speed of light or PI might be related to the length of the fourth dimension, or maybe even the length of the fourth dimension itself. Tom
... I always thought it was simply because the dimensions are "rolled up too tightly", that they're too microscopic for us to detect using modern apparatus. New machines, and new experiments using existing machines, are being devised to bring us to the capability where we will be able to detect these hidden dimensions, should they exist. Experiments will soon be able to validify their existence or deny it. I recall posting about this elsewhere.
Weitzel, The reason I came up with the idea of unstackable or constant dimensions was because I found the idea of rolled-up dimensions so absurd. The curling of dimensions would only complicate things instead of simplifying them. I really don't know who came up with that crazy idea. Anyway, if I am correct, and some dimensions are unstackable, we would only discover their existance by factoring the properties of subatomic particles. If, on the other hand, "extra dimensions" have a large but constant value, we may never be able to prove their existence. They would be indistinguishable from physical constants. Tom
Hi Joeblow, The idea of dimensions being curled is about 90 years old. Einstein was (one of the first) to argue that our 4 dimensional world (spacetime) is curved in a special way. This basically is worked out in his general theory of relativity. And actually, the curved/curled dimension(s) concept makes things easier in physics instead of more difficult. Without a curvature of spacetime, it would be a lot more difficult to explain why gravity makes clocks run slower, or why light is bent in the absence of massive objects. I also think your idea number 2 is exactly the same as the curled dimensions idea. Instead of one meter, you should substitute a much smaller value (I believe it is referred to as the Planck length). Aside from that, good ideas. Keep up the thinking work. Bye! Crisp
Crisp, Einsteins idea of curved space is faulty. He assumed gravity is the result of curved space. The electric field in an atom is almost identical to the gravitational field of a solar system. Does a proton bend space causing the electron to circle it? Obviously it doesn't, since the proton has no effect on a neutron that might be passing by. Therefore, if curved space is not the cause of the proton-electron interaction, why would curved space be the cause of gravitational attraction? I used 1 meter as an example for number 2. I meant that the value can be any number that is constant. In other words, according to idea 1, the length of the "extra dimensions" would be the Planck length. According to idea 2, the length of the "extra dimensions" could be any constant value larger than the Planck length.(This is assuming the Planck length is the smallest length of space). Tom
You are assuming that since an idea is not true for one scenario, it is not true for another that is similar, even though you yourself admit that the electric field in an atom is "almost" identical to the gravitational field of a solar system. I may be mistaken here, but I thought that the electric field in an atom is a matter of electro-magnetics and as far as I know, gravity is not an electromagnetic force. Therefore you are already talking about two different types of forces. If I remember correctly, electrons are held in the atom by the proton because the proton is positively charged and the electron is negatively charged. Neutrons have no charge, and so would not be affected by proton charge.
Gravity and electromagnetism Hi Tom, As Deus pointed out, the analogy of atoms and solar systems cannot be made. You have to be careful mixing two totally different scales of description. An electron is bound to a proton by an electric field. The reason why a neutron does not interact with a proton at low energies is because the neutron is not electrically charged. At higher energies, the neutron does interact with the proton, but this is for other reasons (that's when the strong nuclear force comes into play). On atomic scales, the electromagnetic interaction is the strongest, while the gravitational interaction is about 10^40 times smaller (that is not a typo Please Register or Log in to view the hidden image!). On cosmological scales, gravity is the strongest force (simply because almost any macroscopic object is more or less charged neutrally). However, the two cannot be compared in the way you do: they are two fundamentally different things. Bye! Crisp
Crisp and Deus, The reason I compared the gravity of the solar system with the electric field of an atom was because I wanted to keep it simple. If you prefer, assume you have two large metal spheres, one is charged with a positive charge and the other, with is much smaller, is charged with a negative charge. Take the two spheres into outerspace and push the small sphere so that it begins to orbit the large one. You will find out that you can use the SAME formula to calculate BOTH the attractive forces of the solar system AND the attractive forces of the two spheres(Just replace the masses with charges, and the gravitational constant with the dielectric constant). Deus, As explained above, the formulas are identical. Einstein saw three macro forces: the gravitational, magnetic, and electric. Instead of developing a theory that explains all three of these, almost identical, forces, he only explains one. And he explains it as if it has no relation to the other two. That's just stupid. A theory is supposed to be the result of inductive reasoning(the building of a general fact from a SEVERAL individual facts). Einstein built a general fact from ONE specific fact. What exactly did that solve?? Tom
Joeblow, There is a fundamental difference between the formulas for electrostatic attraction and gravity. The <b>force</b> depends on different properties (charge and mass, respectively). But the <b>acceleration</b> of a mass due to <i>both</i> forces depends on the mass. That means that when we calculate the acceleration of one of your spheres in outer space, we get two different expressions. For gravity we put ma = mg. The mass cancels and we find a=g, which tells us that the acceleration due to gravity is independent of the mass (in Einstein's terms it is an inertial force). But for electrostatics we have ma = kq, where k is a bunch of constants at a particular distance and q is the charge. The acceleration is a=kq/m, which varies with both the mass and the charge. The dependence on mass and charge in electromagnetism means that the Equivalence Principle cannot be formulated for electromagnetism as it can for gravity. Therefore, a curved-space description of electromagnetism is not possible.
I couldn't have put it into better words than James R. did Please Register or Log in to view the hidden image! Bye! Crisp
Crisp and James R, "The dependence on mass and charge in electromagnetism means that the Equivalence Principle cannot be formulated for electromagnetism as it can for gravity. Therefore, a curved-space description of electromagnetism is not possible." I agree, a curved-space description of electromagnetism is not possible. I am arguing that the curved-space explanation of gravity is WRONG. No matter how much you try to make the gravitational and electromagnetic fields seem different from each other, you fail to see the one thing that, without doubt, unites them: ATTRACTION. In both fields there is a force that attracts. If you were to accept the curved-space theory to be correct, you still couldn't explain electric or magnetic fields. But if you can explain the electromagnetic forces, would it be difficult to explain the gravitational force? What Einstein did was he looked at three forces that attract, but made a theory for only one, and a theory that under no circumstances, can explain the other two. That is why I don't respect Einstein. The question is: Can you explain attraction in a theory that encompasses the gravitational, electric, and magnetic fields? Tom
Joeblow, Electromagnetic fields repel as well as attract. Gravity doesn't. If you think attraction is what unites the forces, what about the strong nuclear force? There's plenty of attraction there, too, but again the mechanism is different from both electromagnetism and gravity. <i>But if you can explain the electromagnetic forces, would it be difficult to explain the gravitational force? What Einstein did was he looked at three forces that attract, but made a theory for only one, and a theory that under no circumstances, can explain the other two. That is why I don't respect Einstein.</i> I don't think you appreciate the full scope of general relativity. It is not merely a theory of gravity. It is a theory about space and time. Attraction cannot account for time dilation, the precession of the perihelion of Mercury, frame dragging or gravitational waves. General relativity deals with all of those things and more. Also, GR incorporates electromagnetism into its framework. There is an elegant frame-independent description of electromagnetism in terms of relativistic tensors. <i>The question is: Can you explain attraction in a theory that encompasses the gravitational, electric, and magnetic fields?</i> No, but then, nobody else can either - yet.
And you fail to see the many things that definitely differentiate them. Gravity does not have a repellent affect. EM fields are much stronger than gravity. EM fields obey quantum machanics, gravity apparently does not. EM interacts in wholly different ways with matter than does gravity. Your analogy is like saying Oranges and Apples are the same because they are both round and fruit.
Thed, You're right!! Comparing electric and magnetic fields to gravity is like comparing apples and oranges. For example apples and oranges are both fruits, they both come from plants, and they are made of the same material(atoms, molecules). Unfortunately, you, and Einstein, find more in common between apples and purple elephants than you do between electric/magnetic fields and gravity. Do you find electric/magnetic fields so different than gravity that they couldn't be explained with the same theory? Tom
