# Maximum acceleration

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Is there such a thing as maximum acceleration of mass? For example, mass can't travel at the speed of light. But can the mass of a baseball travel to .5c in one trillionth of a second? Or would it turn into energy?

Thanks.

Greg

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there is no theoretical limit to its acceleration but there are many practical limits.

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In special and general relativity there is no maximal acceleration, only maximal velocity. However, people have looked at modifying relativity to include a maximal acceleration or have discovered such a principle by modifying relativity such as deforming the Poincare algebra. You will have to search the literature for more details.

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Interesting. Another question.. Is it possible to ionize atoms with force alone? I.e. acceleration force overcomes binding coulombs force.

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You'd have to consider how you're applying that force and to what, in what conditions...

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You'd have to consider how you're applying that force and to what, in what conditions...

Do you have any examples where one could ionize atoms with force only?

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Can you supply an example where you're only supplying a force and no energy? The two are intimately linked.

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Is there such a thing as maximum acceleration ...?

...

Good question. It provoked a lot of different reactions.

Not as a direct answer, but as a spin-off, I would mention Unruh temperature.

You could look up Unruh temperature in Wikipedia.

It is a strange fact that an accelerating observer experiences radiation analogous to the Hawking radiation emitted from a blackhole horizon.

Normal acceleration is so small (by universal standards) that this radiation is negligible.

Can't think of anything especially useful to say, but liked the question.

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Interesting. Another question.. Is it possible to ionize atoms with force alone? I.e. acceleration force overcomes binding coulombs force.

I know that in making steel, the steel used to get beaten. In the old days, they used hammers... Hammering it (slightly) changed the chemical structure, and the crystal structure. This possibly changed the electron configurations of some elements present in the steel.

Perhaps you can find more when you search about making steel. I am no expert in this field, I just wanted to give an example and new keywords.

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You could look up Unruh temperature in Wikipedia.

Unruh effect

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Interesting. Another question.. Is it possible to ionize atoms with force alone? I.e. acceleration force overcomes binding coulombs force.

"With force alone" seems a little vague. "Acceleration force" isn't really a thing. Force (of which there are four fundamental types) causes acceleration. Introducing an electric field causes ionization, by applying opposite forces to nuclei and electrons. So I guess the answer is yes, but that's probably not what you had in mind, right?

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Here are a couple sample experiments.

A rotating centrifuge with a positive electric field around its axis, and a negative electric field around its outside border is filled with hydrogen (contained). If the hydrogen could spin around with the centrifuge (a magnetic field might be needed?), and the electric potential was just under the ionization level, could the centripetal force add enough energy to ionize the hydrogen?

Idea #1. If a centrifuge has very strong positive elective electric field on its axis, could the spinning of the centrifuge cause ionization in compounds/atoms? For example, is it possible for the covalent electron to stick to the potential (axis) and the more massive proton could be forced to the outside of the centrifuge overcoming the binding force?

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Good question. It provoked a lot of different reactions.

I would say that it is one of the few "real open" questions we get on here. Any such principle would mean an extension of General Relativity is needed. This could only be a good thing for theoretical physics.

Does anyone know about any experimental/observational results/bounds etc?

Not as a direct answer, but as a spin-off, I would mention Unruh temperature.

Good thought. It crossed my mind if one should direct things towards semiclassical gravity and the Unruh effect and similar. Generally, quantum gravity seems a common theme.

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Any thoughts on the above experiments?

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This sounds stupid, but what if you take the speed of light and divide it by the planck time? Something like the fastest velocity divided by the shortest time ought to give some sort of "planck acceleration." Or am I just digging a mathematical hole here?

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well, if it is able to accelerate then it has mass and if it has mass it will not reach c.

a better approximation would be to calculate the acceleration of a neutrino if you were to dump the entire energy of the universe(minus that of a neutrino of course) into that neutrino in plank time.

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If you have a rocket ship (with unlimited power) that is composed of a specific material how fast would it have to accelerate to lose electrons (energy)? Could this be the same as the unruh effect?

Edited by gre
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If you have a rocket ship (with unlimited power) that is composed of a specific material how fast would it have to accelerate to lose electrons (energy)? Could this be the same as the unruh effect?

Are you asking if it is possible to accelerate an atom to the point of leaving its electrons behind?

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Why would it leave its electrons behind? What do you mean by "electrons (energy)?"

In any case, one limit to acceleration of something like a rocket ship would be the its tensile and compressive strength, since a rocket engine wouldn't directly and equally push on every part of the ship. A big enough force would just rip the "pushed against" parts away from the rest.

That's the kind of thing we (or at least I) are getting at when we ask how the force is applied. Gravity, for example, applies force uniformly to all parts, and so acceleration due to gravity puts no strain on you at all (assuming the field is nearly the same from one end of you to the other). That's why freefall is like being "weightless." Force applied by pushing on something is different, since you're only pushing on the surface atoms (which are accelerated by electron repulsion from the pushing object), which then push and pull on surrounding atoms, compressing and/or elongating the surrounding parts of the object. That's the kind of acceleration you feel.

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Gravity, for example, applies force uniformly to all parts, and so acceleration due to gravity puts no strain on you at all (assuming the field is nearly the same from one end of you to the other). That's why freefall is like being "weightless." Force applied by pushing on something is different, since you're only pushing on the surface atoms (which are accelerated by electron repulsion from the pushing object), which then push and pull on surrounding atoms, compressing and/or elongating the surrounding parts of the object. That's the kind of acceleration you feel.

I wondered about that. If you're in a larger container which drops, you feel that in the pit of your stomach. But, drop from an airplane to skydive, and all you feel is lots of wind.

Also, you're other description makes sense. I've always thought how "warp" drives and black hole drives would rip a ship apart. The former would crumble the ship as its end smashed frontward into the rest of the ship. And the latter would rip the ship's front off incrementally instead of pulling the entire ship at once.

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The acceleration of a photon would be the maximum acceleration (close to infinity minus 1 m/s) i.e a photon reflecting off a mirror due to constructive interference

According to Einstein, the faster you move away, the slower your clock ticks relative to the observer. I'm not sure about this but I believe that this is because the light reflected off the traveller travels slower toward the observer, hence making it appear slower

Right now at this very moment we are travelling at 28670.942 m/s as we orbit the sun, thats just under one ten thousandth the speed of light

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The acceleration of a photon would be the maximum acceleration (close to infinity minus 1 m/s)

infinity minus 1 is still infinity for a start.

also, they do not accelerate. the can't go at any other speed.

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Um, wouldn't the acceleration be $\frac{2c^2}{\lambda}$ or $2cf$? After all, the change is from c in one direction to c in the opposite direction, and it takes time for the whole wave to change direction.

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Um, wouldn't the acceleration be $\frac{2c^2}{\lambda}$ or $2cf$? After all, the change is from c in one direction to c in the opposite direction, and it takes time for the whole wave to change direction.

No, there is no acceleration in photons. They're either travelling at c, or they're not existing.

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No, there is no acceleration in photons. They're either travelling at c, or they're not existing.

They also can't reflect instantaneously, as that would require information traveling faster than the speed of light (all parts of the photon would have to know that the front hit something instantly). But I'm guessing that the front of a photon can be moving in a different direction than the tail, when the photon is reflecting. I guess I should have said "average acceleration". But if photons as you say cannot accelerate, then they cannot change direction either.

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