Relativity

This barely fits in this category, so forgive me. I was wondering the other day in Chemistry why Hg (mercury) was a liquid at STP. I looked into it a little bit and found out that mercury was also the only metal that didn't form a diatomic molecule when in a gaseous state. I read on it, and it said something about the valence electrons of mercury being in the 6s orbital, and the fact that it was so close to the nucleus that the electrons flew at really high speeds around the nucleus and relativity took effect and the mass of those electrons increased. My question is, I thought that relativity couldn't work on such small scales as electrons and such? Or maybe…

hi everyone I don't have an aptitude for physics so I can't answer this for myself but I was curious about something-- Is relativity logically necessary? I mean, would it be possible for a God to create a universe with just Newtonian, and not relativistic, physics? If not, why? And if so, in what way would it be different from this universe? thanks

Two questions: A hand-held torch (on earth) is shone horizontally. What is the path of an emitted photon in earth based coordinates? A photon approaches a black hole, but not head-on. It is deflected and continues past the BH. What is its path?

Hi, I have actually just signed because it is a while I have a question in my mind I can’t find an answer on the net and I hope that some of you could help me out. I start from this quote off another topic by a member of the forum, quote that I find quite interesting for the question I have in mind… In this case it is clear that distance does not affect the size of the two girls but only their perception of each other. And if the analogy is correct as I think it is that it comes the question. It is accepted that gravity affect time. But has it been demonstrate without any doubts that what it is affected is not actually our perception of it? A whil…

According to Einstein, all observers experience and measure the same light speed c, whether they're in stationary position or moving in motion. Okay, this is one of the fundamental parts of relativity, and I'm new at it, so it's still having some difficulty in fully digesting the idea. Let's start at the basic "real world" level first. If I'm driving on the road and going 50mph, and a car from behind me is catching up at 100mph, that car's speed, as it passes me, will not seem as fast relative to my perspective since I'm already in the same forward motion at half the speed. In other words, when it passes me, it won't be traveling 100mph faster than me since I'm no…

I tried calculating the mass of a rotating cylinder but since I got the wrong answer I must have made a mistake somewhere. Can someone check my work and see if they can spot where I went wrong? The derivation is at http://www.geocities.com/physics_world/sr/rotating_cylinder.htm Thanks Pete

Does light experience time? If anything could travel at the speed of light would it experience time? It would seem that photons now arriving at earth from the edge of the universe experience the big bang and then find our earth as it is now with nothing in between. To them it would appear that our world was created in the big bang.

1) What is the ratio/good way to think about time dilation in respect to acceleration? If im going 50% the speed of light am I Expirencing time at 50% 2) Similar to the above statement but in respect to gravitational time dilation? 3) Is there some kinda connection between the two (gravitational/acceleration) as to that my acceleration is increasing my mass, therefore increasing gravitational forces?? 4) for the primary teachers out there, I need a quick refreser on acceleration, velocity, momentum. What is it that is so important to hiszinberg uncertinty? that is the property that describes both trajectory and speed?

Educate me. Here's what I think I know about SR. Please tear my understanding of it to pieces if it's wrong. I want to be humiliated now rather than someday. Thanx, --flk Okay, consider an "event". In particular, consider an (almost) point mass, stationary in space. Call it event A. The same point mass still sitting in the same place, but one nanosecond later, we will call "event B". Now consider the nexus (set of points in spacetime) which have a four-dimensional distance (a spacetime interval) from event A which equals zero. The point mass called "event A" is in that set by definition. But because the interval is a pseudometric (s…

So, most people think of rotation in 3D with respect to an axis, which is like rotating each 2D plane perpendicular to the axis. But relativity says we live in a 4D universe, although time is a rather special dimension. Anyhow, I have several questions about rotation. What would each of the following look like?: *Rotation in the real world. How is the time dimension affected? *Rotation in 4 normal dimensions (called [math]R^4[/math]?) *Rotation in spacetime, along the time axis. *Rotation in spacetime, as if it were [math]R^4[/math] I'm not really sure what I'm looking for, or even if there is anything to find. Maybe I'll have an idea when I see the answers..…

hi i have 2 questions 1) if an object is traveling at more than half the speed of light, and i am traveling in the opposite direction on the same 1d plane at more than half the speed of light, then relative to me, wouldnt the object be traveling faster than the speed of light? i thought nothing could travel faster than light. 2) whats the speed of light like? is it relative to the source? like if i am running and i shine a light, will that light be speed of light + running speed, (when measured from the still ground i am running on)? ps. is this thread in the right section? my first thread, sorry if they're stupid questions, im 16

The following has been known to physicists for (lemme see...) about 80 years. Einstein not only came up with this, but most importantly, he proved it mathematically. NONE of it is either thought up by me, or is my interpretation of anything. But if you didn't already know it, it's really mind-blowing, and that's why I'm writing about it. You can read all about it in this book. It's a textbook for physics grad students, but really, anyone can understand it. Yeah, a page full of nothing but equations looks intimidating, until you look closely and say "Hey, this is nothing but high school algebra, and it's all just the same simple equation written in different …

If someone is holding a photon light clock and they accelerate either up or down the photon would bounce quicker thus creating the appearance of the clock being fast from the point of view of the observer. Is this true?

Hello, I am new here but I am starting regain an interest for sciences and I have come here hoping to improve my understanding and knowledge. I admit, I don’t know a lot but I was hoping by being here that some of you could teach me and change that, if that’s okay. I might be taking a few science class in college and I like to get a head start by learn about a big chunk the subjects before I even start the class’s. So my first question is can some explain to me what the theory of relativity is and how it works to some one has no understanding of it?

I understand that the photon sphere, the circular orbit of a photon, would be at R = 3/2 Schwarzchild radius. This is the geodesic path at that location. But this seems odd. It implies (A) if moving tangentially at greater than R, the photon will pass by with mere deflection. Fair enough. But, (B) it equally implies that if moving tangentially at less than R, the photon would be in a less than circular orbit, which I can only imagine as a spiral towards the BH. But this would imply that the photon sphere is effectively a Schwarzchild horizon for the photon! Where am I going wrong in this interpretation?

Hi I was thinking of two experiments and I cannot figure what would be the results. The experiment are done in a vacuum isolated from any outside electric or magnetic field. A moving charge will generate a magnetic field (it will move the needle of a compas), but if I follow that charge I will not be able to detect a magnetic field. Does the magnetic field exist or not ? The second experiment is 2 equal charge q1 and q2 are moving in the same direction with speed v. If v is greater than a value, I will see the distance between the charge decreasing because of the z-pinch effect. But if I move in the same direction and speed what will I see ?

Why would it take an infinite amount of energy to propel an object at the speed of light? I'm a layman so, as per usual, please correct me if I'm hopelessly misguided... As one approaches the speed of light© the objects mass increases exponentially as it gets closer and closer to c. So the energy taken to move it faster than it is currently travelling increases exponentially as its speed increases(gets closer to c). Light has a finite speed. And numbers have no end (are infinite) and can describe any numerical value, no matter how hopelessly large --> Should the energy not then be finite but almost unimaginably emmence? Is the energy taken simply st…

It's not clear to me why the Lorentz transformation can't be reduced to the Galilean transformation by resetting clocks, rescaling distance measures and fiddling with clock rates according to the recipe on page 11 of A Derivation of the Lorentz Transformation From a Simple Definition of Time and equations (48) to (58). How do you answer this riddle?

In a discussion I got into off the forum there was an objection about a concept that finds use in relativity. The person (who shall remain nameless) who objected based his objection, in part, on the notion that the concept, supposedely, has no meaning in relativistic quantum mechanics. This is clearly a very poor arguement since there is absolutely no reason to expect that all useful ideas in classical mechanics will still be useful in quantum mechanics. For example, the concept of a classical trajectory/worldline looses its meaning when one transitions to quantum mechanics. But one cannot argue that this is a reason to abandon the very useful idea of worldlines in class…

What are cause and effect? Is there really anything to distinguish the two other than saying that one comes before the other? Edit: In the context of relativity you might say that there are two time-like interdependent events. According to any clock, effect would proceed cause. But is there more? Perhaps I could have posted this in the quantum mechanics folder where observation of the wavefunction could be an issue. Re: Distinguishing cause and effect using a clock. Feynman would call a clock a thermodynamic device, where the direction of advance would be determined by conditions of lower entropy in the past light cone than the future light cone. That is, the …

The genesis of the theory of relativity was a long process that involved three major players and their critical reactions to the electrodynamics of moving bodies. Lorentz made a key step when he sought to develop a mechanics that would obey the principle of relativity and Maxwell's equations. Lorentz exploited the invariance properties of the fundamental equations for the interaction between electrons and fields, and thus accounted for the absence of effects of the motion of the earth through the ether, but only to a certain approximation. Poincaré made this absence of effects a general postulate and elevated the principle of relativity even higher than Lorentz di…

okay based on the theory of reletivity light will always go the same speed, even if your going the speed of light and you turn on a light it will move away from you. but from a fixed point of reference it will move the normal speed of light. Now people always talk about needing to find a way to move faster then light to travel to distant stars. BUT it is impossible. because even if we were to be able to go faster then light through some imaginary means, we would just go the speed of light no matter how much faster we were going. BECAUSE, time slows down to equal the speed of light the faster your going. so if you were going faster then light, time would jus…

Does anyone know a good book/website/resource on the mathematics of relativity from an undergraduate/graduate perspective?

Hey. Just hoping people to write facts about Einstein as a normal guy

If i am correct we don't know if gravity is a wave or a particle or what it is. I was just wondering if gravity could be like light and it be a graviton riding on a "gravity wave". Is that possible?