Moderators: please delete this thread. I created it by accident. I didn't get to finish what I wanted to say. (I pressed enter by mistake.)

Edit: never mind.

Why not just edit the post, and enter what you wanted to say?

Done.

Yes induction is not logical proof, just because we observe something to behave the same n times doesn't mean it is going to behave the same the (n+1)th time. In the neat constructed world of mathematics there is such a thing as logical proofs, but in the world we live there are only inferences. Mathematics are an approximation of our universe, applying them to our universe is necessarily based on some untestable assumptions.

The scientifically impossible is fundamentally what scientists believe to be impossible, but a lot of things they thought were impossible turned out to be possible.

Surely our acceptance of the idea that information cannot exceed the speed of light is not the result of pure induction, it is the prediction of Einstein's theories, which are universally accepted by scientists today. It's untrue to say we've arrived at this realisation simply by measuring the speed of flow of our information. This might show light-speed is not exceded, but could not prove why. And without formal proof how can we claim it's impossible ? Don't we infact define as scientifically impossible any act which defies our laws of science? In his time Newton would have called much of what Einstein proposed scientifically impossible, but that just shows how our understanding, and thus our definiton of the scientifically possible, evolves.

Scientific impossibility is logical impossibility in the following sense: If it is the case that I am sitting at a table, then it is logically impossible for it to be the case that I am not sitting at a table (within the same context where the first proposition is true). A scientific theory constrains the world to behave in certain ways, and not others. The logical corollary of that is that if you accept the theory (within some domain of application), then you cannot at the same time accept any proposition that (within the same domain of application) violates the constraints imposed by the theory, on pain of being logically inconsistent.

Now, that answers the narrow question. The closely related wider question is: What is the nature of scientific theories, or the laws of nature, as they traditionally have been called? How are we to make sense of the rules and constraints that they posit? That is a huge topic with a wide variety of views.

In my constructivist opinion, what is impossible cannot even be thought. Impossibility refers to the sentences of a language that have no application in a given language-game.

So, i interpret special relativity as saying that an object of positive mass accelerating to c isn't a meaningful proposition of relativity, i.e. that it isn't even wrong, because it cannot be constructed from the application of the postulates of special relativity.

For what it's worth I consider scientific impossibility to be the current status of some things rather than an absolute dictate of a (so-called) scientific dogma.

- Exceeding the speed of light currently violates the implications of special relativity.
- A perpetual motion machine currently violates the law of conservation of energy.

The status of both would be currently scientific impossibilities.

Now this does not imply that one is forbidden to investigate further into the issue and possibly challenge this status.

I would say with 100% certainty that these attributions of status are not necessarily fixed as absolute as such forever. One cannot prove them 100% to be impossible, but at this current moment in time one cannot prove them to be possible; thus the status remains. Perhaps they will remain unchallenged forever, but one cannot say this with absolute certainty.

This status of scientific impossibility could be refuted, but that would require an actual counterexample and not just the notion that a counterexample might be possible.

If the counterexample can be validated/comfirmed to be actual, repeated under a reasonable/independent tests and reviewed by qualified peers, then the status of scientific impossibility would be removed. This would be a triumph in scientific investigation as knowledge would be refined.

If this did indeed occur, a subsequent challenge as to the reasons why the previously held the status of impossibility failed to function in this case would/must occur. This would imply if the two examples from above had counterexamples to be proven as really occuring, a strong challenge must be made to special relativity or the law of conservation of energy. This would result in a further refinement of knowledge and would be a further triumph in scienctific investigation, in spite of the massive amount of old notions collapsing.

This is all part of the process of scientific investigation and prevents science to become a static dogma of absolute certainity. This prevents scientific investigation from being a system of ideological belief, but rather allows it continual freedom to be a process of continual empirical investigation.

Meow!

G

There are many types of impossibility of which the two that is of concern are:

1. Logical impossibility as expressed in the law of noncontradiction

2. Scientific impossibility, as that expressed in the OP.

Logical impossiblity is absolute i.e. it can't obtain in any possible world and therefore is like the speed of light in science, an insuperable barrier.

Scientific impossibility is relative. There are limits to matter and energy but stepping beyond them doesn't lead to a logical contradiction.

The law of buoyancy says that iron can't float but built the right way, we have iron ships. The impossible by one law of nature becomes possible through another.

I guess when we use the term ''impossible'' we need to qualify it with a context. Travelling at 90% of the speed of light is not logically impossible and not scientifically impossible but is technologically impossible and, probably, humanly impossible.

I have heard it said that during the big bang matter expanded quicker than the speed of light. How can we decide what is scientifically impossible if science cannot agree on what is impossible.

It means in our current understand of science it should not be possible