Physics and Heisenberg

[Vico]

Hi.

I am reading Werner Heisenberg’s *Physics and Philosophy/I]. Can anyone explain this to me?:

*“Michelson’s experiment by Morley and Miller in 1904 was the first definite evidence for the impossibility of detecting the **translational motion ****of the earth by optical methods… If the ether is at **rest **with respect to the sun and does **not move **with the earth, then this fast **motion **of the ether with respect to the earth should make itself felt in a change of the velocity of light… If in a certain system of reference the mechanical motion of bodies fulfills the laws of Newtonian mechanics, then this is also true for any other frame of reference which is in uniform nonrotating motion with respect to the first system. Or, in other words, a uniform translational motion of a system does not produce any mechanical effects **at all **and can therefore not be observed by such effects… Since all systems of reference that are in uniform translation motion with respect to each other are equivalent for the description of nature, there is **no meaning **in the statement that there is a substance, the ether, which is at rest in **only one **of these systems… The electrodynamics of moving bodies can be derived at once from the principle of relativity… The laws take the same form in all systems of reference, which are different from each other only by a uniform translational motion; they are invariant against the Lorentz transformation.”

Not one bit of this makes any sense to me. The rest of what I’ve read so far does, but these tidbits don’t, and when put together seem like a mess of nonsense.

Experiments were done to determine the speed of light in different directions. No difference was found so no motion of the Earth relative to an *aether was detected. The Lorentz transformation formulas (for light) are for time and three coordinates (x, y, z) with a relative velocity between them.

Analogy using a swimmer in a stream. The river flow is analogous to an **aether wind.

http://galileoandeinstein.physics.virginia.edu/lectures/michelson_files/image018.gif*

Michelson-Morley experiment setup:

http://galileoandeinstein.physics.virginia.edu/lectures/michelson_files/image019.gif

 

[JimG]

Ironically, some new geocentrists have used the results of the Michelson-Morley experiment to say that it just goes to show that the earth does not move: it does not move through space, does not circle the sun, does not spin on its axis. They are a strange group. But that’s another discussion entirely.

 

[thinkandmull]

Ironically, some new geocentrists have used the results of the Michelson-Morley experiment to say that it just goes to show that the earth does not move: it does not move through space, does not circle the sun, does not spin on its axis. They are a strange group. But that’s another discussion entirely.

“strange” is a judgment call. The scientific evidence it what matters.

Any, I stopped reading Heisenberg for a while because he keep talking about energy equaling matter, but I don’t know what this has to do with relativity.

 

[JimG]

“strange” is a judgment call. The scientific evidence it what matters.

Any, I stopped reading Heisenberg for a while because he keep talking about energy equaling matter, but I don’t know what this has to do with relativity.

Well, I’m not sure if there is any direct comparison to be made between the famous equation of E = mc^2 and special or general relativity. However, the speed of light, c, does appear in the equations describing such things as time dilation and other effects of relativity.

 

[yppop]

Well, I’m not sure if there is any direct comparison to be made between the famous equation of E = mc^2 and special or general relativity. However, the speed of light, c, does appear in the equations describing such things as time dilation and other effects of relativity.

Jim
E=mc^2 is derived by applying the Lorentz factor to the equation for kinetic energy so the equivalence of matter and energy is a result of the special theory.
Yppop

 

[Vico]

Well, I’m not sure if there is any direct comparison to be made between the famous equation of E = mc^2 and special or general relativity. However, the speed of light, c, does appear in the equations describing such things as time dilation and other effects of relativity.

E = mc^2 was derived from special relativity. He found that for an object approaching the speed of light c, the mass m of the object increased, so to get the particle to a speed of c is impossible. c is the speed of light in a vacuum.

Full formula is http://www.emc2-explained.info/Emc2/deriving_eq9.gifwhich accounts for the relativistic mass increase and the relativistic kinetic energy. Regarding c, recently it was discovered that even in a vacuum, focusing or manipulating the structure of light pulses reduces their speed.

 

[thinkandmull]

“But while one might say a current of 3 amps. was caused by an e.m.f. of 6 volts across a resistance of 2 ohms, one would hardly say that a resistance of 2 ohms in the circuit was caused by an e.m.f. of 6 volts and a current of 3 amps. Why not? Given an e.m.f. of 6 volts, one could make 3 amps. flow by making the resistance equal to 2 ohms. But one could not, given an e.m.f. of 6 volts, make the resistance of the circuit equal to 2 ohms by making a current of 3 amps flow.” Douglas Gasking

Does anyone know what this means?

 

[Vico]

“But while one might say a current of 3 amps. was caused by an e.m.f. of 6 volts across a resistance of 2 ohms, one would hardly say that a resistance of 2 ohms in the circuit was caused by an e.m.f. of 6 volts and a current of 3 amps. Why not? Given an e.m.f. of 6 volts, one could make 3 amps. flow by making the resistance equal to 2 ohms. But one could not, given an e.m.f. of 6 volts, make the resistance of the circuit equal to 2 ohms by making a current of 3 amps flow.” Douglas Gasking

Does anyone know what this means?

The formula used for direct current circuit is E = I * R where E is Voltage, I is Current and R is Resistance. Resistance is opposition to current flow of a material and is temperature dependent. Electrical resistance is the inverse of electrical conductance.

So, the idea is that the voltage causes a current to flow through a conductor at a certain current level. The mechanical analogs are the voltage is pressure and current is flow. If this was a water pipe, then the size of the pipe would determine resistance. So say you had a garden hose and a water source, and turned up the water pressure, then the water flow would increase in the hose. You would not typically be able to increase the size of the hose. So in the electrical example, where the resistance does not change, the voltage drives the current.

 

[Vico]

3 things still confuse me:

1. What does the concept of energy equally matter have to do with relativity
2. Why cannot there be a state of absolute rest?
3. If gravity slows down time, wouldn’t time go faster instead of slower at the speed of light?

For no. 2, there is no* preferred* frame of reference by which to determine absolute rest.

For no. 3, it is part of general relativity that a clock closer to a gravity source moves slower. Special relativity (assuming far from a gravity source) uses the Lorentz transformation: observers moving at different speeds experience different time and length. So time dilation (and length contraction) occurs for each of these and may be combined.

The speed of light is constant, so where the clock is light bouncing between two mirrors, with more gravity the length is shorter so the time is longer.

Look at the formulas to see why the Lorentz transformation shows why ahypothetical observer would see the clock moving slower:

physicsoftheuniverse.com/topics_relativity_special.html

newt.phys.unsw.edu.au/einsteinlight/jw/module4_time_dilation.htm

hyperphysics.phy-astr.gsu.edu/hbase/relativ/tdil.html

 

[thinkandmull]

So something moving very fast would have fast time because it would be less affected by gravity. But when it reaches light speed the time goes even slower than time on earth? That’s how I’m understanding this.

Also:

“But while one might say a current of 3 amps. was caused by an e.m.f. of 6 volts across a resistance of 2 ohms, one would hardly say that a resistance of 2 ohms in the circuit was caused by an e.m.f. of 6 volts and a current of 3 amps. Why not? Given an e.m.f. of 6 volts, one could make 3 amps. flow by making the resistance equal to 2 ohms. **But one could not, given an e.m.f. of 6 volts, make the resistance of the circuit equal to 2 ohms by making a current of 3 amps flow.” **Douglas Gasking

He said this in the context of David Hume. I don’t understand still the last sentence (in bold)

 

[JimG]

So something moving very fast would have fast time because it would be less affected by gravity. But when it reaches light speed the time goes even slower than time on earth? That’s how I’m understanding this.

No. The faster an object is moving, the slower time passes for it. As a moving clock approached the speed of light, time would move slower and slower, approaching zero.

Gravity affects time in the same way as velocity. The greater the gravity, the slower time passes.

The faster the motion, the slower time passes.

 

[thinkandmull]

The fast something goes, the less gravity (thus slowing time) affects it. So should it even out and everything be at the same time?

 

[Vico]

So something moving very fast would have fast time because it would be less affected by gravity. But when it reaches light speed the time goes even slower than time on earth? That’s how I’m understanding this.

Also:

“But while one might say a current of 3 amps. was caused by an e.m.f. of 6 volts across a resistance of 2 ohms, one would hardly say that a resistance of 2 ohms in the circuit was caused by an e.m.f. of 6 volts and a current of 3 amps. Why not? Given an e.m.f. of 6 volts, one could make 3 amps. flow by making the resistance equal to 2 ohms. **But one could not, given an e.m.f. of 6 volts, make the resistance of the circuit equal to 2 ohms by making a current of 3 amps flow.” **Douglas Gasking

He said this in the context of David Hume. I don’t understand still the last sentence (in bold)

There are two scenarios to consider, one from general relativity (gravity) and the other with special relativity (far from a gravity source). These may be summed together depending on the situation to provide the total time dilation (rod contraction).

1. Time runs slower when in a higher gravitational potential.
2. Time of the object moving relativistically, as observed by the stationary observer, is slower.

Since the resistance is fixed, and property of the conductor, the current flow changes in response to the voltage, with a constant voltage source, or the voltage changes in response to the current, with a constant current source.

From post #28: So in the electrical example, where the resistance does not change, the voltage drives the current.

 

[thinkandmull]

On relativity: So the speed has a greater affect on slowing time than gravity.

On currents: Douglas Gasking said that volts plus resistance makes the amps, but volts plus amps do so equal resistance. I’m not sure how this works

 

[Vico]

On relativity: So the speed has a greater affect on slowing time than gravity.

On currents: Douglas Gasking said that volts plus resistance makes the amps, but volts plus amps do so equal resistance. I’m not sure how this works

There is no mention of adding voltage and amperage. The formulas are:

voltage = current * resistance
current = voltage / resistance

 

[JimG]

The fast something goes, the less gravity (thus slowing time) affects it. So should it even out and everything be at the same time?

It seems you are mixing up two different things here. An object is affected by a gravitational field whether or not it is moving. Velocity has no effect on gravity.

Velocity near to light speed does effect time dilation.
So does a strong gravitational field: more gravity slows time, it doesn’t make it go faster.

The relativistic effects of both velocity and of gravity are distinct. One doesn’t cause the other.

 

[thinkandmull]

There is no mention of adding voltage and amperage. The formulas are:

voltage = current * resistance
current = voltage / resistance

I give up

 

[thinkandmull]

It seems you are mixing up two different things here. An object is affected by a gravitational field whether or not it is moving. Velocity has no effect on gravity.

Velocity near to light speed does effect time dilation.
So does a strong gravitational field: more gravity slows time, it doesn’t make it go faster.

The relativistic effects of both velocity and of gravity are distinct. One doesn’t cause the other.

I’ve been told that gravity slows down time

 

[JimG]

I’ve been told that gravity slows down time

Yes, that’s what I said above. The greater the gravitational field, the more time dilation (slowing). And entirely independent of that, increasing velocity, whether in a gravitational field or not, slows down time.

 

[Vico]

I’ve been told that gravity slows down time

Curvature of space-time due to mass. General relativity is a field theory.

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