faster than light?

I prefer characterizing it as a possibility delayed. Now get back to work! I've been told that a better algorithm is needed for the warp field. Who needs to go faster than light if'n you can warp space, right?

 

I bet a grad student made an error and is now fretting telling his/her advisor about it.

 

Ignore function is for those to pusillanimous to have their POV challenged.

Think positive dang-it! My headline would read:

"Grad Students error leads to faster than light discovery and FTL drive!"

Bon-voyage! :whoo:

 

Problem Solved!

Speedy neutrino mystery likely solved, relativity safe after all | DVICE

Calculation oversight in GPS signal corrections.

 

FPD,

Thanks for the followup.

The scenario described sounds maybe vaguely sorta'-kinda' somewhat
related to a situation I had to be prepared to answer in my middle
school science class this week.

The question I could anticipate coming up was, Would a projectile fired
straight up land on the spot it was fired from? (We have built and are
firing catapults and trebuchets. Cool!)
Simplifying assumptions: the atmosphere is absolutely still and not
moving with the earth's rotation (a hint at the answer there!)
The gravity of the sun and the moon will not affect the flight path.

Pondering on this, I've come to the belief that due the earth's rotation,
the projectile would land somewhere off in a westward direction, the
distance dependent on the time the projectile was in the air. The time
being a function of the height reached. (Velocity, drag, etc, not
necessarily having to be addressed, at least at first... )

The question hasn't come up yet, but I think I'm ready just in case.

Back to the neutrino: Am I correct to think that it was the rotation of the
earth that was the source of the neutrino experiment's error?

 

I thought the experimenters only used GPS to measure distance

Didn't they sync atomic clocks here on earth and used that as the clock? Why did they rely on the GPS clocks?

 

Cool.

If the atmosphere is NOT moving with the Earth's rotation, that means you will be experiencing a 1000 miles per hour wind. That might effect the trajectory slightly.

A good thought experiment is, "how would a bullet act differently than a laser?"

 

Presumably you mean the opposite: the atmosphere is absolutely still and moving in synch at all altitudes with the earth's rotation, otherwise the wind would flatten everything.

You could eliminate the problem of atmosphere by relocating the experiment to the Moon, and relocating the Moon to a stationary point between Andromeda and the Milky Way, but keep it spinning. Shoot something straight up (that won't reach escape velocity) and it will fall some distance away from the direction of rotation, because its horizontal velocity only equals the surface velocity, which is the slower than the velocities it would need while at higher elevation to keep up with the launch point beneath it.

 

Exactly right.

 

No, they also used GPS to provide the time tagging of the emission and detection of the neutrinos.

GPS Clocks provide traceability to the Master reference of UTC time. The issue was not that their time was wrong, it was that they essentially overlooked a correction factor caused by the speed of the earth's rotation. If the experiment had been performed in Antarctica, the issue would not have been detected. If the experiment had been performed on the equator, the error would have been larger. The technical name for the effect overlooked is "Lorentz Contraction".

 

Corwyn, Airportkid, and Florida_Prius_Driver,

Thank you for the gentle corrections to my simplifying assumptions on
the vertically shot projectile problem... the atmosphere will rotate with
the earth.

I thought about moving the experiment to the moon to avoid
atmospheric affects, but that would take it outside of the experiential
references of the students.

The bit about the surface of the earth having a velocity of ~1000 MPH --
differences in latitude overlooked -- is a cool factoid.

It brought to mind a thought experiment for the students:

What would it mean if the earth instantaneously stopped spinning on its axis?

Simple answer:
Almost every one on the surface of the earth would die.
Why?
We would all be slammed into the eastward wall of the space we
occupied as it collpsed around us.
What about people in cars, etc?
Slammed against buildings, rolled over and over violently if in open
country.
What about on the oceans, lakes, etc?
There would be massive "tidal waves" on the westward facing shores.
And in the middle of the oceans?
Ships might survive.
What about trees and buildings?
Virtually all would be knocked down with the debris field going off to
the eastward.
Would folks in an airplane high overhead, or migrating birds be affected?
Not immediately.
But where would the planes land?
What would happen at locations close to the North and South Poles?
What would be the effect from possible motion of the tectonic plates?
Unimaginably catastrophic earth quakes -- as if it would matter...

I can see getting this far quite quickly in a guided discussion.
Effects of the resulting 1000 MPH wind and perhaps even magnetic
disturbances due induced turbidity in the earth's core could come later.

Thanks again.

 

A projectile fired straight up would actually follow a parabolic path (or something similar) with an eastward component due to the eastward velocity of the Earth's surface. I think that to a first approximation it would land back on the launch spot, but atmospheric resistance slows it, thus taking it out of a perfect parabola. Exactly what effect this would have is beyond my analytical abilities. The lower the initial velocity and the lower the drag, the closer it would land to it's firing point.

The difficulty of performing the experiment lies in the difficulty of firing a projectile exactly straight up, and finding a windless day to do it on.

Because the post does not count, I don't mind that in all likelihood, everything I've written in the above two paragraphs is probably wrong.

 

The planet itself would probably disintegrate. Certainly the thin few miles thick crust of loose rock and water would hurl into space as a massive cloud of debris, dragging the atmosphere off with it. The mantle and core would most likely break apart, lacking the tensile and sheer strength to hold together under the instantaneous change of momentum.

I don't know whether the ruins of the planet would dissassociate to distances beyond gravity's ability to pull it all back together, or would remain a local clump of material that would gradually repack under gravitational attraction, but for anyone on the surface, in the air or undersea when it happened, no one would ever know what hit them.

 

Tried that experiment at 2102 EST. Nothing happened on the earth that I could see, but the rest of the universe suddenly started rotating around the earth.

 

+1

 

The surface is moving at a small fraction of orbital velocity, much less escape velocity, so none of the debris would escape to space.

(I neglect heating effects on the atmosphere, which would temporarily increase the 'evaporation' loss rate at the top of the atmosphere.)

As for what would destruction happens when the spinning stops, I can't speculate without some proposed braking mechanism, allowing us to draw a dividing line between which parts are forced to stop and which will try to continue moving.

 

ound::drum:

 

For a summary of some actual U.S. Army tests, find a copy of the NRA Firearms Fact Book, and look up "Falling Bullets'.

The Army folks in 1919-1920 were interested in the interaction with the atmosphere, so there is no mention of Earth's rotation.

 

The Earth could not suddenly stop rotating unless a suitable outside force were applied. This is because of the LAW of conservation of angular momentum.

If such a force were applied, we must ask what is the nature of the force, before we can answer what would happen. Is it a force that acts simultaneously upon every atom within the sphere from the outermost layer of the atmosphere to the Earth's center? If so, all that would happen is that the heavens would appear to stop rotating above us. Eventually the sun would bake one side of the Earth and the other side would freeze, with consequent catastrophic effects upon weather patterns. Is it a force that acts upon just the atoms in the solid materials but not the liquid? If so, all the water would continue moving east at 1,000 mph, with the obvious consequences. Does the force act upon people? Buildings? If not, those would continue moving east until they hit something.

If we wish to fantasize about a "miracle" in which the law of conservation of angular momentum does not apply, then "what would happen" is whatever we wish to make up, because fantasy is whatever we want it to be.

In short, the question "What would happen if the Earth suddenly stopped rotating?" is unanswerable because we need information regarding the force or make-believe scenario that causes it to happen.