speed of light

The laws of nature aren't so much given laws by which nature obides as they are our descriptions of what we observe in nature. In this sense, we don't know what makes anything a rule, but based on what we see we propose patterns and then test the predictions our patterns make to see if they are applicable to reality and to what extent.

Now classical speed, or Galilean velocity if you will is indeed relative. It is an approximation of the motions at speeds far below the speed of light. As things move faster, i.e. closer to the speed of light however we find that those models are too simplistic and increasingly fail to describe and predict observations. In the early twentieth century this was mostly theoretical and was hard to observe so it followed from other laws that were in turn easily observable. Now, with particle accelerators, we can actually induce high velocities and observe the resulting behaviour of mass. Now since I didn't thoroughly cover relativity myself, I shan't start with those and then deduce relativistic equations from them.

Now there is the so-called energy-momentum relation, an equation that relates any object's rest mass m₀, momentum p and total energy E:



where c is the speed of light.

Since the rest mass of a light quantum (and I mean any electromagnetic quantum, of course) is zero, you can see that the energy of a photon reduces to E=pc and since a massive object at rest has zero momentum (because in that case p=m₀v where v is the object's velocity), its energy at rest reduces to E=m₀c².
Now, we can trivially expand the latter equation by v/v=1 resulting in


and with mv=p


Now we solve for pc and feed that into our initial equation to get



Solving for E² we get


As you can see, as v approaches c, the denominator approaches zero and therefore the total energy E of that object approaches infinity. In other words, the faster you go, the more energy it takes to accelerate any further.

As for the change of mass, we come for the momentum p, twisting the variables we have so far around a bit, to

And since p=Mv where M is the total mass of the object, this reduces to

As you can see, the total mass of an object not only doesn't decrease with increasing velocity, but indeed, the opposite is the case: As a massive body accelerates approaching light speed, it actually quite rapidly gains mass, which explains why it gets increasingly impossible to accelerate it further the faster it already moves.

I would like to stress that I am very much a layman at this point. While the conclusions, as far as I know, are correct, I presume that my ways of getting to them that I presented here may be severely flawed in several places. Bearing that in mind I hope it was still marginally helpful.

no matter what you got my brain buzzing so yes it was helpful certainly

i wonder if traveling backwards in time would cause mass to transform into light

if mass gains mass as it picks up speed the only thing i can think of as the opposite of speed is reverse time

i may not be much of a scientist but im a pretty good story teller lol

it bothers me that speed of light is not possible

what if i build a machine which turns a cylinder to produce energy

the cylinder is originally turned through nomal magnet power but its got electro magnets attached also

the produced energy is stored into a capaciter or a battery
or something - every time a certain amount of energy is stored; let.me call it just call it 10

whenever 10 is stored 1 gets fed back into the spin of the cylinder by being directed to the electro magnets

the idea being that the more power used to turn the cylinder the faster it goes - every time it reaches the next 10 it puts another 1 back into the system making the cylinder spin just a little faster

unless it explodes its an infinitie progression - doesnt it HAVE to reach the speed of light eventually?

Study!! This 9 videos are great to see the relation between time & space. I am still studying.
KSP Special Relativity ( 1 of 9 ) Introduction : http://youtu.be/KKAwpEetJ-Q

A little song that I like (interlude)
Shall we gather at the river? : http://youtu.be/Qca8B5NbX5Y

Others video on relativity
Albert Einstein's Theory of Relativity : http://youtu.be/ev9zrt__lec

Relativity and Time Dilation : http://youtu.be/aZrjMmMBa_8

Don't contest the light....
Simple Relativity - Understanding Einstein's Spec… : http://youtu.be/TgH9KXEQ0YU

OB1Shinobi wrote: i wonder if traveling backwards in time would cause mass to transform into light

Positrons are sometimes thought of as electrons traveling back through time. They still have mass and are still not quite the same as a light particle... Then again, with only one direction of time available to our observation as of now, it is difficult to say. I wouldn't know why mass moving back in time should suddenly lose its mass. In fact, if its energy stay constant, then that'd mean it would have to gain momentum and why that would happen is also currently beyond me. In any case, numerous reactions, most prominently nuclear fusion and fission, operate on the equivalence of mass and energy. When you burn a piece of paper and you conserve the smoke and the ash, the total mass of the system will in fact decrease and the light and heat the flames emitted amount to just that difference.

if mass gains mass as it picks up speed the only thing i can think of as the opposite of speed is reverse time

Speed is defined as the euclidian norm of velocity. Let x and y be arbitrary linear independant directions, forming a two-dimensional vector space. Let t be time, vector v be velocity and v be speed.

Now, even with t being negative, indicating 'reverse time', if you will, since it is in every instance being raised to the second power, the entire expression can never be negative. Speed is always either zero or positive.

what if i build a machine which turns a cylinder to produce energy

You would win more than just the Nobel Prize. Before you get too hopeful though, bear in mind that such a device would violate the first law of thermodynamics and patent offices grew so tired of people trying that many have special policies on machines with that ambition.

the cylinder is originally turned through nomal magnet power but its got electro magnets attached also

It could be originally set in motion by a user or by a convenient assymmetrical configuration of electromagnets. You are describing an electromotor right now.

the produced energy is stored into a capaciter or a battery or something

every time a certain amount of energy is stored; let.me call it just call it 10

whenever 10 is stored 1 gets fed back into the spin of the cylinder by being directed to the electro magnets

So you are saying that for every one unit of energy it gets it puts out ten? Essentially what you are describing is an electric generator, which is a reverse electric motor, if you will, but this one not only doesn't lose any energy to friction, it somehow produces energy out of thin air. Where do the additional nine units come from?

the idea being that the more power used to turn the cylinder the faster it goes - every time it reaches the next 10 it puts another 1 back into the system making the cylinder spin just a little faster

unless it explodes its an infinitie progression - doesnt it HAVE to reach the speed of light eventually?

Unless your machine is made out of light rather than matter, it will have a rest mass. If it has a size, that mass will also not be located on the rotation axis but actually somewhere where it will experience motion. And as by the formula above, so long as the rest mass is not zero, with increasing speed, total mass will, again, increase ad infinitum. So even if we had a motor that we would feed more and more energy into the device, as long as we only have finite energy at our disposal, no part of it will get to light speed, eventhough we can get very close indeed. If we did have a self-sustaining device that could actually conjure up energy out of nowhere, until it reached light speed, literally infinite time would have to pass, because in a finite time only a finite amount of energy would be generated. The only way to get massive objects to light speed is to conjure up infinite energy in an instant.

i think what im describing is technically a magnetic dynamo

yes it could initially be set in motion by a light touch
actually even that wouldnt ve necessary i think

generally speaking its my thought that the basic dynamo concept could be applied to every hinge and sliding surface in a home which would mean that every time someone opened their refrigerator or cupboard or any door in the house they would generate a small charge of elecetricity which would be stored in a central battery or whatever the appropriate storage device may be

the dynamo was an elaboration on this concept so that the energy didnt have to be produced manually

if a dynamo is light enough at its fulcrum (ive found that others have thought of this part - there are magnetic fan blade dynamos on youtube) to be rotated by the influence of the normal magnets

but it also has electric magnets ready to add to the amount of magnetic pressure applied to the rotation of the cylinder or the fan blades (which was how i originally thought of it too) the the first thing the dynamo does is to create energy

this energy is stored until it reaches 10 points

the 11th point of energy is applied to the electric magnets

this cycle is repeated

also the 1-10 ratio is completely arbitrary

its probably not the most apporopriate ratio for either energy production for a home or for reaching light speed -though i guess im letting go of that ambition for the time. the point was free clean energy and this device would do that if my assumption about our technological ability to store measure and reapply electric energy and my understanding of electric magnets are both accurate

I am sure is possible to make free energy. Now they are working on nanotube of carbon. Thats really more advanced for the english im mastering but perhaps you are going to understand something.

Self Org. Systhems Vector Equilibrium Flower Of… : http://youtu.be/9n-vb71VZzk

Free Energy and the Equilibrium Constant : http://youtu.be/F1k8TJsVg_g

Einstein on faster-than-light speeds? : http://youtu.be/l9aLyfFnfOU

And nano carbon? It's military sciences. They are not giving the tech even if we need it to make plasma lightsaber... We are going need to do it with telekinesis.
There are some stone that have rubidium. Thats substance in gaz are the one who make the light with mass. Right now they are using this Tech for make quantum computer. A rubidium onze cost much more than gold.

When you ride your bicycle and switch on the dynamo on the go, you will immediately notice how it is slightly harder to push the pedals. When you open the fridge, the energy you put into the door moves the door. If you want to harvest that motion, you mount a spring on the door that will move some sort of harvesting device like a generator. You will be storing some energy, but you will also spend more on opening the door because now it is retained by an additional spring. That energy in turn will come from your body's metabolism, i.e. respiration, water consumption and food processing. Ultimately all we have is the materials Earth provides and radiation from the sun. An ideal closed system would retain all of its energy in a form that is still useful to keep the system going. The second law of thermodynamics disposes of that possibility. If in addition to keeping all the energy one wants to actually produce any, I'm afraid physical reality has an impressive track record of disappointing them.

The sun is the most free energy source at our disposal. To harvest it either directly or through biomatter is as close as we can get to free energy. And plenty at that, if we go as far as building a dyson sphere around it, but there will not come a machine that conjures up energy out of nothing unless it runs on magic. That's not a matter of technology either. That's just the universe we have to deal with for it is the one we've been dealt.

If something travelled at the speed of light, would it stop being a physical object if it became light? or would it simply travel so fast that it passes through some kind of barrier, abit like a sonic boom when the sound barrier is broken.

i shouldn't have peeked into this thread....all those formulas....triggering my college algebra ptsd..... :sick:

https://www.youtube.com/watch?v=ev9zrt__lec


this video proves that im on to SOMETHING - not that im right per se but that i am generally interpreting the relationship between light and time in a functional way

im going to spend a good bit of time on these and other related videos

this is an awesome thread
thanks to everybody
keep it coming!

Still pondering the OP, I guess the relativity aspect is a way to move things from A-B at ultra high speeds, as in if you fly really fast here on Earth, your speed is (for this most practically) relative to the air mass - how hard your pushing the air out of the way (to move).

The speed of sound's sonic boom is all about how the air handles that type of impact. Previously the design and construction of aircraft had failed before the air's uniformity had. In space obviously there is no air, so I wonder what other types of fields you might impact which associate some concept of relative motion..... gravity, radiation, dust!?

So how do we design a 'spacefoil', something which creates not lift to defeat gravity like an aerofoil, but vacuum to defeat relative motion.... I think it might need to be a variation of a Star Trek transporter which operates a disassembly field to the front, turning all matter into energy, which then zap's it out the rear into a reassembly field. Overcoming the relativity by turning everything to energy and moving it through 'vehicle' at the speed of light!! I think what I'm saying is they did not need to blow up the Earth in the Hitchhikers Guide, they just needed to pass through it
:woohoo:

An interesting fact I heard recently is that the speed of light is changing. Not kidding.

the speed of light can be affected by the medium through which it passes...

http://www.livescience.com/29111-speed-of-light-not-constant.html


this is all from the article linked above

author Marcel Urban of the Université du Paris-Sud, looks at the cosmic vacuum, which is often assumed to be empty space. The laws of quantum physics, which govern subatomic particles and all things very small, say that the vacuum of space is actually full of fundamental particles like quarks, called "virtual" particles. These matter particles, which are always paired up with their appropriate antiparticle counterpart, pop into existence and almost immediately collide. When matter and antimatter particles touch, they annihilate each other.

Photons of light, as they fly through space, are captured and re-emitted by these virtual particles. Urban and his colleagues propose that the energies of these particles — specifically the amount of charge they carry — affect the speed of light. Since the amount of energy a particle will have at the time a photon hits it will be essentially random, the effect on how fast photons move should vary too.


Gerd Leuchs and Luis Sánchez-Soto, from the Max Planck Institute for the Physics of Light in Erlangen, Germany, say that the number of species of elementary particle that exist in the universe may be what makes the speed of light what it is.

Leuchs and Sanchez-Soto say that there should be, by their calculations, on the order of 100 "species" of particle that have charges. The current law governing particle physics, the Standard Model, identifies nine: the electron, muon, tauon, the six kinds of quark, photons and the W-boson. [Wacky Physics: The Coolest Little Particles in Nature]

The charges of all these particles are important to their model, because all of them have charges. A quantity called impedance depends on the sum of those charges. The impedance in turn depends on the permittivity of the vacuum, or how much it resists electric fields, as well as its permeability, or how well it supports magnetic fields. Light waves are made up of both an electric and magnetic wave, so changing those quantities (permittivity and permeability) will change the measured speed of light.

"We have calculated the permittivity and permeability of the vacuum as caused by those ephemeral virtual unstable elementary particles," Soto-Sanchez wrote in an email to LiveScience. "It turns out, however, from such a simple model one can discern that those constants contain essentially equal contributions of the different types of electrically charged particle-antiparticle pairs: both, the ones known and those so far unknown to us."

Both papers say that light interacts with virtual particle-antiparticle pairs. In Leuchs' and Sanchez-Soto's model, the impedance of the vacuum (which would speed up or slow down the speed of light) depends on the density of the particles. The impedance relates to the ratio of electric fields to magnetic fields in light; every light wave is made up of both kinds of field, and its measured value, along with the permittivity of space to magnetic fields, governs the speed of light.

Some scientists are a bit skeptical, though. Jay Wacker, a particle physicist at the SLAC National Accelerator Laboratory, said he wasn't confident about the mathematical techniques used, and that it seemed in both cases the scientists weren't applying the mathematical tools in the way that most would. "The proper way to do this is with the Feynman diagrams," Wacker said. "It's a very interesting question [the speed of light]," he added, but the methods used in these papers are probably not sufficient to investigate it.

The other issue is that if there really are a lot of other particles beyond what's in the Standard Model, then this theory needs some serious revision. But so far its predictions have been borne out, notably with the discovery of the Higgs boson. This doesn't mean there aren't any more particles to be found — but if they are out there they're above the energies currently achievable with particle accelerators, and therefore pretty heavy, and it's possible that their effects would have shown up elsewhere.

A fact is a point of data that is either indisputable in that it can through logical analysis be concluded from true premises, or undisputed because of the massive amount of evidence indicating it and no other in its place. The changing behaviour of light speed in a vacuum is not a fact. Indeed, almost all VSL hypotheses attempt to redefine the speed of light as a function of distance rather than distance as a function of that speed. In this way, most of the proposed hypotheses are mathematically equivalent to the constant light speed models. This is why in the main stream nobody has a problem defining the speed of light rather than measuring it; because it is a definition of units first and of relative quantities second. It is like if you had an empty vector space and you arbitrarily chose an origin point and defined directions and dimensions from it. There is no reason for picking the ones that you did over any other except that your choice may be more convenient for most calculations. Variable speed of light hypotheses propose a new convenience, they don't explain a discovery.

If you haven't already, you guys should see Interstellar

Looks like they've been able to slow down, stop, and restart photon's in fiber optic cable... or something like that!?

In a vacuum, the speed of light is always the same - approximately 300 million meters per second. When light is sent through a medium such as glass or water, it is slowed down a little bit due to its interaction with the material.

"In our system, this effect is extreme, because we are creating an exceedingly strong interaction between light and matter", says Professor Arno Rauschenbeutel (TU Wien / Vienna Center for Quantum Science and Technology). "The speed of light in our glass fiber is only 180 kilometers per hour. Any express train can top that."

By coupling atoms to glass fibers light was slowed down to a speed of 180 km/h. The team even managed to bring the light to a complete stop and to retrieve it again later. This technology is an important prerequisite for a future glassfiber-based quantum-internet, in which quantum information can be teleported over great distances.

http://vcq.quantum.at/
https://www.tuwien.ac.at/en/tuwien_home/

all i can say is WOW

i dont even have a guess what the implications of this might be but its absolutely fascinating that light can be made to stop and then start again!

Consider:

where E is the energy of a photon, nu is it's frequency, lambda the wavelength and c_M it's phase speed in the medium used to slow it down.
Now, they might have slowed down the photons to almost a standstill. On their scales 180km/h might as well be zero, for that matter. But a full stop is mathematically inconceivable unless the same relativity that made their machines work in the first place turned out to be quite wrong indeed.

Oh, and there is another problem with that, too. You see, refraction isn't magic. All media have an actual refraction index n defined as the fraction of the speed of the wave outside the medium over it's speed inside, or
n=c₀/c_M

So for a medium to force the phase speed of light down to zero it'd have to have infinite refraction which is likewise impossible. So classical physics flies out the window also.

I recommend reading the research papers over trusting popular science magazines any day. This is just another example why.

i see what youre saying for the most part

i definitely get the relativity of motion aspect

or i definitely THINK i do lol

basically, true stillness is mathmatically impossible

because

in a relative universe, if anything moves then everything moves, yes?

this line of thought makes me wonder how light moves to begin with

like i guess im assuming that inthis fiber optic situation being described that they could slow down the photon my increasig the density it traveled through (?) and then they could decrease that density and it would speed back up- but what is the mechanism or the process by which it regains its momentum after slowing down?