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Wendybabe

Einstein's Theory Of Relativity

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Guest VigCS

Davka summed it up pretty well.

 

This guy on youtube has a huge amount of shows about space, physics, evolution, etc. There's some good stuff about relativity on his page:

 

http://www.youtube.com/profile?user=Zuke696&view=playlists

 

Also, "The Elegant Universe" starts off with about an hour's worth of Relativity, but it's mainly about string theory. It's a really interesting documentary with high production values.

 

http://www.youtube.com/view_play_list?p=F0E4651FBF0FB34F&search_query=the+elegant+universe

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Guest Davka

I've understood that the speed of light is dependent upon the medium through which it travels. I'm also aware of an experiment where a ray of light was able to travel 310 times faster than it otherwise could by passing it through some sort of gas. It actually passed through completely before it finished entering somehow. Now, I know that light is malleable by way of the medium, which means that the absolute speed of light cannot be exceeded, merely adjusted by the medium.

 

That said, I'm also aware of a woman who recently was able to bring a pulse of light to a complete halt, then return it to its natural speed and send it on it's way. If what you say is true, then what happened there?

 

I'd have to read the studies in order to offer any opinion on them. I'm no expert by any means, just a guy with a history in journalism who has some experience with making things more understandable to other non-experts.

 

I haven't heard of either of the experiments you reference, but I have read about light being slowed way the hell down and then accelerated again. It's usually on the quantum level, where they are messing with a few photons at a time. Frankly, when you start talking about what's going on at that level, I'm not sure anyone has a real answer. Experiments have also showed that one photon can literally be in two places at once, and that completely unconnected muons ( I think it was muons) which have become 'entangled' can actually have what appears to be an instant causal relationship - i.e. when you affect one, the other reacts identically and simultaneously.

 

Luckily, Einstein's theory doesn't require a lot of understanding of quantum physics. Einstein himself rejected some of the core ideas behind quantum mechanics, specifically the idea of randomness. This is the reason for his famous "(God) does not play dice (with the universe)" quote. Einstein was convinced that the quantum model was flawed, and that there must be a more rational, predictable basis for reality.

 

OK, I just became aware that I am officially rambling, and fast approaching incoherence. I'll shut up now.

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Guest Icedender

Many thanks! :grin:

 

 

Karl Sagan's Cosmos has an episode dedicated to explaining relativity. If you have Netflix you can watch it online Here it's episode 8 "Journeys in Space and Time"

 

his delivery is dry but its got a ton of information in it.

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Guest ephymeris

I was totally getting this til your post LagMaster! Now I'm all confuzzled again!

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I am expected to know this for an upcoming Astronomy class. I try and try to read up on it but it never sinks through. Please someone?

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REALITY CHECK!! The truth is… Einstein was entirely WRONG with his theories. Hawking is way off in his view of outer space. They both amount to Science Fiction at best. The entire universe is made of Plasma. The simple equation to describe the universe is: Plasma + Electric Currents + Magnetic Fields + Matter = The Universe as we can see it. The truth is that Electric currents are the strongest forces in the universe. Magnetic fields are the second strongest force. The two forces together draw the matter together forming all the galaxies we see in the universe. Gravity is nothing more than a word used to describe the fact that matter is held down on this planet. Gravity does not do all the absurd things claimed by the Mainstream astrophysics crowd. There are NO Black Holes, Dark Matter, Dark Energy Time Warping, Space Bending Light Bending going on anywhere. AND.. The Big Bang never happened.

If you want the real facts… Go to Youtube and do a search for: “Thunderbolts Of The Gods”… “Electric Plasma Universe”… “Symbols Of An Alien Sky”

 

Read the works of: Wallace Thornhill… David Talbot… Donald Scott and many others who understand how the universe actually functions.

 

 

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REALITY CHECK!! The truth is… Einstein was entirely WRONG with his theories. Hawking is way off in his view of outer space. They both amount to Science Fiction at best. The entire universe is made of Plasma. The simple equation to describe the universe is: Plasma + Electric Currents + Magnetic Fields + Matter = The Universe as we can see it. The truth is that Electric currents are the strongest forces in the universe. Magnetic fields are the second strongest force. The two forces together draw the matter together forming all the galaxies we see in the universe. Gravity is nothing more than a word used to describe the fact that matter is held down on this planet. Gravity does not do all the absurd things claimed by the Mainstream astrophysics crowd. There are NO Black Holes, Dark Matter, Dark Energy Time Warping, Space Bending Light Bending going on anywhere. AND.. The Big Bang never happened.

If you want the real facts… Go to Youtube and do a search for: “Thunderbolts Of The Gods”… “Electric Plasma Universe”… “Symbols Of An Alien Sky”

 

Read the works of: Wallace Thornhill… David Talbot… Donald Scott and many others who understand how the universe actually functions.

 

 

 

lol lrn2physics

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BTW, the speed of light is not set in stone. There's some wiggle-room. When we talk about the speed of light, what is generally meant is the speed of light in a vacuum. Light travels at different speeds through different mediums, but it travels fastest in a vacuum.

I've understood that the speed of light is dependent upon the medium through which it travels. I'm also aware of an experiment where a ray of light was able to travel 310 times faster than it otherwise could by passing it through some sort of gas. It actually passed through completely before it finished entering somehow. Now, I know that light is malleable by way of the medium, which means that the absolute speed of light cannot be exceeded, merely adjusted by the medium.

 

That said, I'm also aware of a woman who recently was able to bring a pulse of light to a complete halt, then return it to its natural speed and send it on it's way. If what you say is true, then what happened there?

Experiments where c has been exceeded normally are misunderstood by people who don't get the involved maths. 

 

Light, of course, is both particles and waves at the same time. Understanding the faster-than-c experiments require understanding some aspects of waves.

 

A wave in motion has several simultaneous velocities, and these can even move in opposite direction. 

 

Group velocity could easiest be described this way: take a snapshot of the wave form. Move the snapshot along the wave, so that the snapshot and the wave form line up constantly. The velocity at which you have to move the snapshot is the group velocity. On occasion, this may exceed c. 

 

Front velocity is the velocity at which the onset of the wave form travels. This does not exceed c, nor can any part of the wave surpass it afaict.

 

Phase velocity is a bit more difficult to describe and I can't actually describe it in any manner that is comparably easy to the former, but here I am going to attempt:

pick, say, a point on the wave that is at amplitude zero, and as the amplitude at that point increases, slide down continuously to the nearest point on the wave that is at zero. Repeat. The velocity at which the zero-point moves (or wavecrest or halfways between closest crest and zero or whatever) is the phase velocity, and this is the thing you can get that most routinely surpasses C. However, it cannot be used to transmit information faster than C, and no matter how fast your phase velocity, it can never travel ahead of the front of the wave.

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Why not another 2013 entry -- yellow.gif

 

Einstein's theories of Relativity come in two parts. First in the early 1900's he presented his theory of Special Relativity. This is based upon the concept that time is not a constant and that its measurement is relative to the time frame and motion being considered, where time for the same event will be measured differently depending upon the time-frame motion where it is measured/ considered/ calculated. The speed of light, the distance per unit of time, however, will always accordingly be measured to be the same regardless of the time frame or its relative motion. One tenet of the model is that there is no background field needed to explain the math of this model (no aether needed). The calculations of the model are equivalent to "Lorenz transforms." which were presented before Einstein's model but required an aether for their explanation.

 

Einstein's second theory of Relativity was presented in the mid 1920's, and is called his General Theory of Relativity which was Einstein's theory of gravity. It is based upon the concept of the bending or warping of space rather than gravity as a force, such as in Newtonian gravity. In this model time is included as a dimension in its mathematical formulations, which proposed the concept of spacetime, where a point in space cannot be separated from the time of measurement. The formulations of General Relativity are non-Euclidean, meaning space does not necessarily follow in straight lines, or non-converging parallel lines. The math of General Relativity was the basis for his cosmological equations, which was/is the foundational math for the Big Bang cosmological model.

 

Both Special and General Relativity are still both considered totally valid, but the new ad hoc hypothesis of dark matter was/ is needed to explain stellar and galactic motions at galactic scales -- without it GR greatly fails predicatively concerning galaxies and the universe as a whole. Their are now rival theories of gravity but none yet considered serious contenders.

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Why not another 2013 entry -- yellow.gif

 

Einstein's theories of Relativity come in two parts. First in the early 1900's he presented his theory of Special Relativity. This is based upon the concept that time is not a constant and that its measurement is relative to the time frame and motion being considered, where time for the same event will be measured differently depending upon the time-frame motion where it is measured/ considered/ calculated. The speed of light, the distance per unit of time, however, will always accordingly be measured to be the same regardless of the time frame or its relative motion. One tenet of the model is that there is no background field needed to explain the math of this model (no aether needed). The calculations of the model are equivalent to "Lorenz transforms." which were presented before Einstein's model but required an aether for their explanation.

 

Einstein's second theory of Relativity was presented in the mid 1920's, and is called his General Theory of Relativity which was Einstein's theory of gravity. It is based upon the concept of the bending or warping of space rather than gravity as a force, such as in Newtonian gravity. In this model time is included as a dimension in its mathematical formulations, which proposed the concept of spacetime, where a point in space cannot be separated from the time of measurement. The formulations of General Relativity are non-Euclidean, meaning space does not necessarily follow in straight lines, or non-converging parallel lines. The math of General Relativity was the basis for his cosmological equations, which was/is the foundational math for the Big Bang cosmological model.

 

Both Special and General Relativity are still both considered totally valid, but the new ad hoc hypothesis of dark matter was/ is needed to explain stellar and galactic motions at galactic scales -- without it GR greatly fails predicatively concerning galaxies and the universe as a whole. Their are now rival theories of gravity but none yet considered serious contenders.

I think there probably is a need for even more 2013 posts here - but preferrably by someone more well-versed than me in it - as nearly all the posts previously made (even ones that got their fair share of admiration), especially those by Davka are pretty much wrong. This part, for instance, is entirely irrelevant to relativity:

 

"Here's the deal: everything is made of the same thing. Light, matter, energy, time, space - absolutely everything in the universe is the same basic stuff in different forms. At a very tiny level, a single "unit" of the universe, the smallest possible thing/energy/light particle that can exist, is a quantum. Plural quanta. From the word "quantity." As in "smallest quantity possible." Thus the phrase "quantum physics." Let's call the stuff everything is made of "quantum stuff.""

 

What also is omitted throughout the thread until your post is length contraction, which is pretty important a thing to understand if you are to understand why C is the same in all reference frames.

 

Also, geodesics are a helpful concept which no one seems to have mentioned at all.

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I think there probably is a need for even more 2013 posts here - but preferrably by someone more well-versed than me in it - as nearly all the posts previously made (even ones that got their fair share of admiration) ...............are pretty much wrong.

 

What also is omitted throughout the thread until your post is length contraction, which is pretty important a thing to understand if you are to understand why C is the same in all reference frames.

 

Also, geodesics are a helpful concept which no one seems to have mentioned at all.

 

 

 

Yes Miekko,

 

The concept and mechanics of Length contraction were first proposed by Lorentz and FirzGerald, and is still called Lorentz-Fitzgerald contraction. Both collaborated to accordingly explain why the Michelson-Morley (MM) experiment could not detect an aether. They proposed  that the M&M experiment would accordingly change dimensions in such a way, based upon the high speed rotation of its components, that even if an aether existed it accordingly could not be detected by thier equipment. The idea of length contraction was quintisential to Lorenz's equations which are equivalent to those later presented by Einstein in his theory of Special Relativity.

 

Einstein's instead proposed, via Special Relativity, that this contraction effect was not a dynamical aether effect, but rather a kinematic effect due to the change in the proposed notions of space, time, and simultaneity.

 

As to geodesics: defined: "Of, relating to, or denoting the shortest possible line between two points on a sphere or other curved surface."

 

General Relativity proposes the notion of non-linear space. It proposes that in space a straight line becomes a geodesic part of curved space, which via its math proposed the new concept of spacetime, where time is formulated as a dimension of space. Accordingly a freely moving or falling particle always follows a geodesic path.

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I am by no means even capable of talking about relativity with any degree of authority.  However, a somewhat novel application of relativity can be used in part to explain some of the strange properties of certain elements. One that comes to mind is the Mercury atom in its elemental form. Mercury is unique in that it is a liquid at room temperature. Why is it a liquid when other what we call transition metals are solid at room temperature? I did not have a clue until I had to do a presentation on the liquidity of Mercury for one of my classes.

 

It is an interesting question and one not easily solved by traditional thinking. The easy or most fundamental way of looking at an electron in an atom is something known as the Schrodinger Wave Equation. It is sort of a fundamental equation of quantum mechanics. It’s predictions work perfectly for simple atoms such as the Hydrogen atom or one-electron atoms. Anything with multiple electrons; however, cannot be solved exactly and we need to use various perturbations and approximations. These approximations are very good at making accurate and precise predictions however. 

 

The standard methods, so to speak, do not fully account for the liquidity of Mercury. However, special relativity is used to save the day so to speak. We know from special relativity that as an object with mass approaches the speed of light, the mass of that object essentially increases as we need to add more and more energy to said object as it approaches closer and closer to the *speed of light. This is why objects with mass can not go the speed of light because you would need an infinite amount of energy get the object up to the speed of light. This also means that as electrons approach the speed of light, they too are subject to this and other relativistic effects.

*I use speed and velocity interchangeably here knowing full well that velocity is actually a vector value. Be gentle on me if you are a real physicist.

 

In a Hydrogen atom, the electron typically “lives” in a low “energy level” state where it moves at a very small fraction of the speed of light and the effects of relativity are negligible.  However in large atoms like mercury where the electrons are in certain “configurations,” they are subject to significant relativistic effects. I want to try to keep things simple, but complicated formulas that a physicist named Paul Dirac developed in essence combine special relativity and quantum mechanics to account for these relativistic effects.

 

Basically, the crux of this story is, that special relativity is a critical component of explaining certain properties of certain elements.  I am not sure if this added much to this thread, but it is a neat application of special relativity.

 

End Note:

 

For you math hounds, the basic formula for calculating the relativistic mass of an object that moves at speeds closer to the speed of light is actually pretty simple to use.  It takes the following form:

 

Relativistic Mass = Mass at rest divided by / square root of (1 - (velocity of the object/speed of light) squared

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Curious,

 

Your comments are good but believe the chemical explanation of why Mercury is a liquid at ambient temperatures is simpler, not totally explanatory, but for simplicities sake it is preferable for most beginnning and intermediary chemistry students. 

 

All metallic elements have three phases of existence, as solids, liquids and gasses. As a gas most, such metallic gas is made up of free atoms, as this gas cools some gas molecules can form. As it cools farther eventually the atoms and molecules will aggregate in the air becoming heavy enough to rain down and pool as a liquid. Of course this also commonly happens with many molecules such as water. Mercury has both a low melting and vapor point so that it takes less heat for it to turn into a liquid, and less heat than other metals to become a gas.

 

At -37.89 F degrees mercury can freeze solid and mercury thermometers can break. At 674.1 degree F. mercury, at ambient pressures, will start boiling and become a gas.  In contrast other common metallic appearing metals have melting points far higher such as gold at 1945 F ; aluminum 1170 F ; Zink 787 F. ; lead 621 F. ; Cadmium at 610; and tin at 449 degrees F. So above 621 degree, at ambient pressures, all four metals will be liquid: Mercury, lead, cadmium, tin. Because of the high atmospheric pressure, of the listed metals, maybe only mercury and tin could be liquid on the Venusian surface which can reach 900 F.

Mercury has 2 available valence electrons so it can not easily form chemical bonds with other elements or molecular bonding with itself of liquid of gas. And to become a solid most energy must be taken away from it for it to become a soled, down to about - 48 degrees fehrenheight (F).

 

As to why Relativitic effects do not get into chemistry books, in general, is because such effects with relativistic methods still can only be estimated in most cases, but some relativistic estimates would seem to better explain some sophistication, actions/ reactions/ conditions better than other methods of estimation. Here is a link:

 

http://voh.chem.ucla.edu/vohtar/fall02/classes/172/pdf/172rpint.pdf

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Thank you for the great follow up post.

 

Funny, that is one of the sources I initially looked at when preparing for the presentation I had to do. 

 

I would certainly not talk about this in any detail in an introductory chemistry course.  I just wanted to point out another way that special relativity can be used. Interestingly enough, I will be looking at Mercury in much more depth over the next year or two, but the organomercury compounds are the ones I will be focusing on.

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