Using Centrifugal Force to Travel the Speed of Light

[Lieutenant172]

Hi everyone! I'm new here and just thought I would share an idea. I've been thinking about the possibilities of humans using centrifugal force to travel the speed of light.

 

First, lets think about a simple scenario. If I use a leash to tie my cat to the ceiling fan, he will travel much faster than the fan blades themselves. If I extend the length of the leash, his speed will increase.

 

Now lets look at this concept at a larger scale. We all know that the earth has massive amounts of energy while spinning on it's axis. At the equator, the surface of the earth is travelling at about 1,000 miles per hour. So what if we attached a wire to the surface of the earth and extended it beyond our atmosphere?

 

I believe that we could advance to the end of this wire and take advantage of the earth's energy to reach amazing speeds. If there are no limitations to the length of the wire, then there are no limitations to the speed that we can travel. All we need to do is let go... and we can go anywhere we want to at speeds faster than light.

 

Any thoughts? Thanks - Ron

[Erasmus00]

If you do a calculation similar to the one I carried out in this thread http://hypography.com/forums/showthread.php?t=3185&page=1&pp=10 you'll find that even in this situation, light speed is a limit.

-Will

[Lieutenant172]

If you do a calculation similar to the one I carried out in this thread http://hypography.com/forums/showthread.php?t=3185&page=1&pp=10 you'll find that even in this situation, light speed is a limit.

-Will

 

First, lets assume that earth (or another planet) has enough energy to keep its rotational velocity during this situation.

 

So if light speed has a limit, then what will occur if the length of the connecting wire is extended beyond the point required to reach light speed? How can light speed be a limit? If the wire were millions of miles long, then the tail end would be travelling really really fast (exceeding light speed).

 

Thanks - Ron

[Erasmus00]

First, lets assume that earth (or another planet) has enough energy to keep its rotational velocity during this situation.

 

So if light speed has a limit, then what will occur if the length of the connecting wire is extended beyond the point required to reach light speed? How can light speed be a limit? If the wire were millions of miles long, then the tail end would be travelling really really fast (exceeding light speed).

 

Thanks - Ron

 

What would happen is that the middle of the wire would get ahead of the front of the wire, and you'd set up waves traveling down the wire.

 

A similar situation, this one for faster then light signalling, that intro physics students sometimes bring up is to connect two planets with a rigid rod. You could then send signals at faster then light speed by wiggling the rod on the one planet and the other planet gets them instantly. The problem is that you set up traveling waves in the rod, and the signals really only propagate at the speed of sound for the rod material.

-Will

[Little Bang]

Given that all things work as you suggest. As your ship startes approaching the speed of light it's mass will approach infinity, That will tend to put a slight amount of stress on your wire and the Earth.

[UncleAl]

I've been thinking about the possibilities of humans using centrifugal force to travel the speed of light.

The usual hype is spinning a searchlight and claming the beam superluminally traverses circumference at a sufficently large radius. Then we have closing scissors with really long blades, banging on an infinitely rigid girder, falling into a black hole... Einstein-Podolsky-Rosen collapse, quantum tunneling, wave superposition...

 

http://gregegan.customer.netspace.net.au/APPLETS/20/20.html

 

It's all crap as a superluminal physical modality - and trivially so. Special Relativity is a self-consistent axiomatic geometry. It contains no internal errors; it cannot b internally disproven. Internal inconsistencies in SR (meaning inconsistencies of a purely mathematical logical nature) automatically lead to contradictions in number theory, itself, and arithmetic, since the mathematics of Minkowski geometry is equiconsistent with the theory of real numbers and with arithmetic.

 

Any physics possessing Lorentz Invariance contains a finite lightspeed identical for all inertial observers. You then have the beta factor for mixing observed space, time, and mass with relative velocity,

 

beta = sqrt[1 -( v^2)/(c^2)]

 

where "v" is relative velocity and "c" is lightspeed. In this universe c is set by the observed permittivity and permeability of vacuum.

 

c = 299,792,458 m/sec

 

Inertially observed mass is [(rest mass)/beta]. Attempts to relativistically accelerate mass empirically converts added energy to mass and asymptotically doesn't change velocity.

 

No physical object can be spun up indefinitely. It will hold together only as long as the kinetic energy per unit mass (in any locality) is no larger than the binding energy per unit mass. The most tightly bound solid is diamond, with a tensile stregth of about 10 tonnes/mm^2. For a single crystal diamond sphere, the limiting equatorial velocity (independent of the size of the object) is given by

 

v_lim = sqrt(2*S/rho)

 

where "S" is the yield strength and "rho" the density. 10 tonnes/mm^2 translates to about 10^11 Pa (100 gigapascals). Diamond density is about 3500 kg/m^3.

 

v_lim = 7600 m/s

 

or about 4.7 miles/second or about 0.0025% of lightspeed... or about the velocity of low Earth orbit. The fastest spinning bodies in the universe, millisecond pulsars, hit surface velocities around 30% of lightspeed. OTOH, they are solid neutronium bound by 10^12 gees of surface gravity.

[CraigD]

Let’s try your model, Lieutenant172, with a couple of simplifying assumptions.

 

Assuming the wire to be of negligible mass and unlimited strength and stiffness, so we don’t have to worry about any complicated, flexing dynamics.

Instead of a single wire, have 2, on opposite sides of the Earth, so that the Earth’s center of mass/rotation doesn’t change, with a 500 kg mass on each end.

Chose a length of wire, R, that would produce a velocity greater than the speed of light if the Earth’s rate of rotations was unchanged – about 6*10^13 m, or 400 times the distance from the earth to the sun , would give about 1.5*c.

 

Now, the total energy of the Earth – M*c^2 - isn’t changed by any of this.

 

Before raising the wires, the Earth’s total energy is given by (M0/(1-(V0/c)^2)^.5)*c^2, where M0 is the Earth’s rest mass (~6e24 kg) , V0 its velocity due to the rotation of the earth (~460 m/s , if we simplify the distribution of Earth’s mass to put it all exactly at the surface)

 

After raising the wires, it’s given by (M0/(1-(V0/c)^2)^.5 + M1/(1-(V/c)^2)^.5)*c^2, where M1 is the total mass (1000 kg) on the end of the wires, and V is it’s velocity. Note that, from simple geometry, V0=V*R0/R, where R0 is the Earth’s radius (~6400 km)

 

If you solve the equation (the algebra is surprisingly difficult, so I’d suggest you use a numeric estimation method, though you’ll need an very high or arbitrary precision calculator), V is amazingly close to c – something like .999999999999999999962. M0 is decreased, slowing the earths rotation to about a 36 hour day.

 

So, if you can handle the engineering challenge of deploying a wire 10 times longer than the orbital diameter of Pluto, prevent it from getting obliterated by near-lightspeed collisions with interplanetary dust and debris, etc, you’d be able to use a fraction of the earth’s kinetic energy to accelerate a couple of good-sized masses to very, very nearly, but not quite, the speed of light.

[Jay-qu]

this has been asked a few times here (once by myself) and no its not possible, the forces dont propagate at or faster than the speed of light...