A Physics Thought Experiment

[MoonSailer]

Okay this is a thought experiment so we will assume that technical difficults don't exist.
I built a cannon that shoots cannons. each cannon gets smaller but is able to shoot it's projectile 25,000 miles a second. So the first cannon is shot and the second is going 25,000 mps and it shoots the third which is then going 50 000mps. This shoots the third going 75,000mps. This can continue indefinately . Why can't this eventually lead to a cannon traveling at over 186,000 mps relative to the initial starting point ????? Is the light speed limit real???? I know that they have not measured anything going faster than light speed but is this a technical problem or a result of the light speed limit????

 

[Bilbo]

Okay this is a thought experiment so we will assume that technical difficults don't exist.
I built a cannon that shoots cannons. each cannon gets smaller but is able to shoot it's projectile 25,000 miles a second. So the first cannon is shot and the second is going 25,000 mps and it shoots the third which is then going 50 000mps. This shoots the third going 75,000mps. This can continue indefinately . Why can't this eventually lead to a cannon traveling at over 186,000 mps relative to the initial starting point ????? Is the light speed limit real???? I know that they have not measured anything going faster than light speed but is this a technical problem or a result of the light speed limit????

Isn't that similar to early multi-stage rocket concepts?
Here's something:
http://www.usd.edu/phys/courses/phys300/gallery2/dave/dave.htm

I always thought that it may be solved by harnessing gravty from large objects and thus slingshotting forward.
Apparently it takes vast amounts of mass/energy to move that fast.
Another question,
Saytwo vehicles are moving at 0.51 speed of light and they pass each other in opposite directions. Aren't they moving faster that the speed of light relative to each other?

 

[Jerry Clark H356 SV Persi]

Speed of Light is like the Sound Barrier

This is an interesting thought thread. In the instance where the two objects are moving toward each other, their closure speed is speed of light plus .2. Mathematically, if L = speed of light, then L + 1 is faster than the speed of light, therefore, mathematically the speed of light can be broken.

If you were following a vehicle at the speed of light and the front vehicle exceeded the speed of light, could you see it?

Where is Chuck Yeager when we need him?

 

[letterman]

Re: Speed of Light is like the Sound Barrier

Chuck Yeager broke the sound barrier...in level flight. Boyd, A guy from Erie PA and a military test pilot, broke it days earlier in a regular military jet, in a dive. He was buried with Marine and Navy honors, and was the only man to be so honored (besides the Presidents.) Yeager got the gold because the Gov't sunk so much money into the X-1, they MADE it be the first to break the barrier. Nothin like rewriting history.

 

[Eddie7045]

Wasn't the Theory of Reletivity a way of

saying that matter is, in essence, an arrangement of energy. The speed of light then would be a calculated point that you might not actually reach but can be understood like Absolute Zero. In the case of the speed of light, that speed can be measured when energy is in the form of a formless force (light, electricity, ect) but does matter actually transform at that point? It might be that any form of matter cannot go beyond the speed of light without losing it's form as matter.

 

[Sailm8]

This is just a variation on this link.
http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/headlights.html

 

[MoonSailer]

On a PBS program the other night they said that time slows near massive objects such as black holes. Maybe there is a ground field effect. Too strange for me. It would seem that if time slows near a massive object that light near the sun would travel more slowly than light out near the earth.
The cannon ideal is that the smaller cannon will always be accellerated relative to the larger cannon.
I really like the ideal that once you reach light speed you are in another dimension and no longer interact. Kind of like higher energy shorter wavelength gamma photon penetrate matter farther rather than interacting as a lower energy photon does.

 

[T37 Phil]

It's called special relativity. Look up time dilation and space contraction. For the cannons going near light speed, the cannon they shoot is still travelling at launch velocity in the inertial frame of the cannon that launched it (which is moving relative to the initial inertial frame). Those cannons are, however, moving at near light speed relative to the initial inertial frame. So if you're standing on cannons at the end of the line, you see the cannon you shoot move away at launch velocity. If you are standing on the first cannon, then you see the later cannons move away at near light speed.

 

[MoonSailer]

I guess that may be true but the reason that we never see anything going faster than light might be because we see with light. Perhaps we can't see electromagnetic radiation that travels fasster than the speed of light because it stops interacting wit matter in the same way. Kind of like hull speed on a boat. As long as a boat travels below planning speed it must travel at a particular wave speed. BUT once it reaches planning speed the rules about hull speed no longer apply!!!!!

 

[T37 Phil]

Not exactly. It's absolutely true within the context of the theory, a theory that has experimental data to support it. Within that theory, nothing with mass can travel at a rate greater than c due to energy constraints. Massless particles travel at c. What you are proposing is a violation of the theory and perhaps it could find a place within some other theory, one that must still explain what has been observed already.

Most sailboats don't truly plane at any speed; hull speed for displacement mode is just that, hull speed. It's also not a speed limit, like c is. You can push a boat past hull speed, it's just an enormous amount of drag that needs to be overcome.

For the powerboat, going from a slow displacement mode to a planing mode changes the nature of forces acting on the hull. For massless particles, there is nothing analogous in the theory. Massless particles have velocity c in the theory, period.

And finally, our eyes may see with light, but our technology sees much more. Proposing that something exists that does not interact with matter in a regularly detactable manner leads to a theory that cannot be proved or disproved, and is therefore not science.

 

[MoonSailer]

I am thinking more along the lines of Quantum theory. You know where radiation of a particular wavelength will only interact with electrons in a particular quantum state. We use this all of the time in my laboratory. UV light at 260nm and 280nm is used to quantitate DNA/RNA or protein. The 260nM interacts with RNA and much less with protein. The 280nM interacts with the aromatic rings in some amino acids. That is why Xrays work. The very short wavelengths only interact a little with most of the body but interact with bone more strongly. Gamma radiation can penetrate several feet of lead!!!! So if you could make gamma radiation go faster than C would it interact with matter at all??? I agree that this is not science but idle speculation...a thought experiment. But Einstein himself was a big fan of thought experiments. http://hyperphysics.phy-astr.gsu.edu/hbase/mod3.html
,, http://plato.stanford.edu/entries/thought-experiment/

 

[T37 Phil]

Yes, Einstein was a great fan of thought experiments.

The specificity of interaction between particular wavelengths and particular molecules has to do with their chemical structure. That structure is determined, in some sense, by quantum theory, but doesn't require some exotic theory to explain it. As far as x-rays, they work in medical imaging because tissues, bone in particular, have differing electron densities and therefore provide a signal with constrast on the image plate. It's not that bone more absorbs that wavelength preferentially.

I'm not sure what you mean by "make gamma radiation go faster". Again, massless particles travel at c in a vacuum by definition in relativistic theories. If there is something undetectable that goes faster, well...

There are by the way, as I recall, tunneling experiements based on quantum mechanics that do claim to reach speeds (of "information" flow) greater than c. Of course, their are also those that claim quantum theory makes time travel possible (and demonstrable). I think the interpretation of the tunneling data is debated by physicists. Or possibly I'm just remembering wrong.