Johnny5

I don't want to get into this debate with you. Regards

Space isn't a tangible thing to be created. The big bang was most definitely an explosion in space. The reason I am right has to due with the impedance of the vacuum, it's literally zero. And I don't mean electrical impedance, and I don't mean our local vacuum, which isn't a true vacuum. Regards PS: If I'm wrong prove it to me.

In "reaching" to disagree with you, I noticed something. I do agree that the current universe supplies evidence as to the, and I use this word cautiously, 'effect' of the big bang, but I do disagree that we aren't provided evidence as to what happened in the past (cause), and here's why: Understanding the laws of physics really is understanding motion. And we have seen enough of 'motion' in our lives to have an almost intuitive understanding of how the universe changes as time moves fowards. In some people that intuition is large enough for them to at least imagine time running in reverse. So I think the fact that we experience enough of time in one direction, allows us to understand the laws of physics, and by understanding those laws, we can reasonably be expected to "mentally run time in reverse." So the evidence we have (which is foward in time evolution of the universe) actually does give insight into how the past must have been. We are not totally without means to properly infer the initial conditions. I guess that's all I am trying to say. To act as though it is impossible for us to ever understand the initial conditions of the universe is not only misleading, it is wrong, for the reason I am trying to state. I will give you a really simple example of what I am trying to say. You know that when you drop a feather, it must fall to the earth. You have a reasonable sense of how long this takes, depending upon the initial height you drop it from. And you probably also know, that if you drop a book at the same height that you drop the feather from, that the book falls much faster, given that you released them simultaneously. But now, you have learned that if you place the feather on top of the book, that the book acts like a shield, and shields the feather from the effects of air resistance, and the two now fall collectively (together) with the same acceleration, namely g. So all this knowledge comes to you from experiment, and sensory perception. The experiment is repeatable, and the truth value of your knowledge isn't changing in time. So you can say you know something, and then explain it to someone who doesn't. Then, using your knowledge, which has increased, you can construct a hexagon on paper, much like euclid taught how to, and then cut it a certain way, and construct a propeller. In fact, you can figure out how to make a device that actually rises in the air, from the simple knowledge i am discussing now. But the point to notice is that, if you saw an apple hit the ground very slowly, you could confidently conclude that (in the past, at the moment it was dropped) it wasn't dropped too high above the earth. Conversely, if you saw that same apple smash into the earth and explode at 120 mph, you could conclude that it was dropped much higher (in the past). So from looking at just a few moments in time, and knowing a bit about the laws of physics, you can understand what things were like earlier. The present doesnt give much evidence about the past, but it does give evidence. So I disagree slightly with you. And I think it would be the crowning glory of modern physics, to clearly show that we have discovered the initial conditions of the universe, through experiments that were not principally designed to find that information. Whew, ok I'm done. Regards

I have a bold suggestion. Why don't you actually derive the formula for E^2 clearly, and then when you are done, explain the experimental origin of formula E=hf in some detail. Regards

Why do you keep insisting that the speed of a photon is a constant?

You have the speed of a photon being independent of the motion of the source, does that not bother you? Regards

Good question. Well do you know how much time there was from the first moment in time up to the big bang, say in units of seconds? And really, I guess i am interested in interpretations of the Planck units. Regards

I am interested in modeling a photon as a particle that can accelerate, but I am not sure about where to begin. What I have been doing is this. I first define the position of the photon's center of inertia in a frame as follows: [math] \vec r = x \hat i + y \hat j + z \hat k [/math] Then velocity as follows: [math] \vec v = \frac{d\vec r}{dt} [/math] Now the magnitude of the photon's velocity is its speed in the frame. So this is a theory of a variable speed of light. I use the following formula for the speed of a photon in a frame: [math] |\vec v | = f \lambda [/math] I am not sure how to interpret photon frequency just yet, and photon wavelength just yet, but I am treating the relation as valid in the frame. Now, to get to the magnitude of the acceleration i have: [math] |\vec a| = \frac{d}{dt}(|\vec v |) = f \frac{d\lambda}{dt}+ \lambda \frac{df}{dt} [/math] Has anyone seen this approach to variable speed of light theories? What is the next step? I want to relate the general photon speed v, to the speed c, relative to the emitter. Note: [math] \frac{dc}{dt} = 0 [/math] Regards

The question is pretty much self explanatory. Total energy=? Total mass=? Temperature=? Volume=? Density = ? Also, while I'm on the subject, what is the escape velocity of the universe, way back in time when all the matter was concentrated near the center of the universe? Thank you

No you shouldn't just give in like that. I am asking you to explain yourself better. Regards PS: Think about the postulate I just pulled out of the air.

Would you mind explaining the bold part a little more?

Here is your post #32: Here you ask, "how can pc=hf when f is variant, and pc constant?" First let me point out that momentum p is a vector, although the magnitude of that vector is a scalar. As for pc being constant... why do you assert that? [math] p = \frac{h}{\lambda} [/math] Where lambda is the wavelength of the object in question, and h is Planck's constant of nature. So P varies inversely with lambda. Postulate: [math] c = {f}{\lambda} [/math] Hence [math] p = \frac{hf}{c} [/math] Hence: [math] pc = hf [/math] Regards

This didn't make any sense to me. If x denotes the position of something, and its position changes, depending on how you define the differential of position, the answer you get will either be positive or negative. Regards

I assume that's what he meant too. But why didn't he just say that 'time' is infinite, without referece to space. That 'time' is infinite is obvious. I interpret that as meaning that relative motion cannot cease. (Newtons laws have this, thermodynamics has this). That time is 'infinite' (really unbounded) can be inferred from very basic observations about the macroscopic behavior of the universe, and here i am treating time separately from space. Aside: That space is infinite is obvious, because we are not enclosed inside some infinite solid shell. I don't mean to quibble, its just that when I read that "spacetime" is infinite, my first thought was, "of course relative motion cannot cease". Regards

Telling me that it is a well known equation which you have learned doesn't answer the question. I clearly see that you say you aren't sure what type of energy is given by the above equation. Why don't you try deriving it so you do know? And then after you know what 'kind' of energy it is, then you will be able to decide whether or not it is equivalent to (hf)^2? Regards

What do you mean when you say that space-time is infinite? Regards

Post 32 where? Regards

Albert, consider things initially. You have a trailer sitting on the planet earth. The trailer has 1000 kilograms of inertia. Then there is a rope attached to it, and a car that is to pull the trailer. Initially, there is no tension in the rope, its just hanging there. Then the car is turned on, and slowly moves fowards, until the rope is horizontal. At that moment in time, the tension in the rope is zero, and we have three objects at rest relative to each other... 1. trailer 2. rope 3. car Now, as the car inches fowards, the rope stretches slightly (this fact comes from reality). And while the rope is stretching, the center of mass of the trailer isn't changing position in the rest frame of the earth (much). The car pulls more and more, and the tension in the rope increases until finally the trailer starts moving in the rest frame of the earth. There was a "frictional force" which the car had to overcome first, in order to get the trailer to accelerate in the rest frame of the earth. In introductory physics, that force is proportional to the weight of the trailer. The weight of the trailer arises from the fact that the trailer is in a gravitational field. In introductory physics we have W = weight = m g m is the inertial mass of the trailer g is the acceleration due to earths gravity at the surface of the earth, and local to the trailer. In SI units... g = 9.8 m/s^2, by experiment. The magnitude of the force due to friction is given by: [math] F_f = \mu_s N [/math] Where N is the normal force, and "mu sub s" is the coefficient of static friction between the trailer and the earth. The normal force has the same magnitude as the weight of the trailer, but its direction is opposite to the trailer's weight. That is: W+N=0 Hence, there is no motion of the trailer up into the air, or sinking into the earth. The value of the coefficient of static friction depend upon the particular objects in question, and has to be measured. Now, once that frictional force is overcome, the trailer and car are moving together (collectively) in unison, at the same speed. If it is true that a frictional force acts upon the trailer at all moments in time whilst its moving along the road at a constant speed, the rope must always be applying an equal and opposite force to the trailer by Newton's third law. (where we assume Newton's third law is true in the frame of earth, in which the speed is constant.) Therefore, the tension in the string cannot be zero, because it is exerting a force on the trailer equal to the frictional force of the road on the trailer, but in the opposite direction. And it is true that a frictional force acts upon the trailer as it moves along the road. Hence the tension in the string cannot be zero, even when the car isn't accelerating relative to the road at rest. Regards

You can depending upon the student. It might help you to know that I know a lot already. Thank you

Answer me a question please. In the formula you have right here; [math]e^2 = (pc)^2 + (m_0 c^2 )^2[/math] Is it the case that: [math] p=\frac{h}{\lambda} [/math] ? And my second question is, what does e denote? My third question is, how did you derive the formula? Thank you

This is getting all screwed up' date=' because no effort is being made to derive the formula [math'] E^2 = (pc)^2 + (m_0 c^2)^2 [/math] The derivation can be made to come from only one assumption, namely: [math] M = \frac{m_0}{\sqrt{1-v^2/c^2}} [/math] Your formula is [math]E=(pc)^2 + (m_0 p^2)^2[/math] Where I have taken the liberty of writing e=E=total energy. Your formula is not... [math]E=(pc)^2 + (m_0 c^2)^2[/math] Why are these two formulas different? Regards