what Proof would convince the entire world that Aliens are visiting this planet ?

Carl Sagan actually talks about this:

"...a scraping of the whole ship, and the discovery that it contains isotopic ratios that aren't present on earth, chemical elements form the so-called island of stability, very heavy elements that don't exist on earth. Or material of absolutely bizarre properties of many sorts—electrical conductivity or ductility. There are many things like that that would instantly give serious credence to an account."

Actually there are a whole lot of things - an alien astro-navigation chart or book in an alien language which included an English translation and disclosed facts about physics or math we currently are close to discovering but remain unknown at the present time.

A method of detecting alien civilizations which is just beyond our current knowledge, utilizing an advanced device, some kind of super telescope, or even a medical device like that in ST:OS which can heal non-invasively. Virtually any field of science would have something just beyond our knowledge that upon disclosure would be good evidence the information came from elsewhere than Earth. An inertial-less space-faring vehicle (one that could travel directly without using orbital boosting.)

Having said that, any technology would have some degree of suspicion, and could even be items from our own future, but something along those lines would be hundreds of times better than just a 'story' without supporting trace evidence.

Obviously it couldn't be too close to our own technology, such as a mere 4 petaflops computer. However a 50 petaflops computer in a handheld would be a start.

Oh, another good piece of evidence would be something that has eluded us for years - a battery-sized power source of great capacity that could power a large vehicle, or power a household by plugging into it. Again, it could also be a futuristic device, but I'd put that on par, probability-wise, with evidence of aliens. (both are similarly unlikely, with future time travel slightly less believable than alien visitation, imo).

Purists might say just having a gadget or a heavy element isn't proof they're here - after all they could have 'sent' the device by some FTL method which precludes sending biological specimens. But most would be willing to stipulate on that that solid proof of existence is a good first step.

I presume you're responding to my comment. Your conjecture, while well-taken, is non-responsive to the original question.

The question was not what any visiting aliens -should- give us, just what items or information would be considered solid -evidence- (not proof, mind you) of alien presence (not -visitation-, necessarily).

So again, given a long list of possible evidence, let's just say some kind of advanced mathematics - a currently unsolvable proof for a theorum.

Here's a short list of 16 of them.

Hi EN,

Again, I just posted a quote from Carl. I didn't say I agreed with his assessment in toto. There are a few problems with any evidence.

Also, people keep confusing 'evidence' with 'proof'. There's only one science that entails PROOF and that's pure mathematics. We're just talking about solid evidence. For just about any scenario it's not difficult to come up with problems which would lead to a dispute of the evidence, so due care and diligence is a requirement.

But just about anything along the lines of valid trace, or valid math theorem proofs or physics theory would be acceptable evidence.

All the evidence we have now consists of stories, some corroborated with radar tracking, or with multiple witnesses. BUT, we all know that human perception can be fooled - so as far as solid documentation, witness testimony, I don't care if 1,000 people witness and video a light in the sky performing seemingly possible aerobatics, it does not rise to the level of solid evidence of non-terrestrial, non-human visitation (though it might be evidence of 'high strangeness). (holograms or RPV could potentially duplicate it, both terrestrial and within current technology).

So, again, solid evidence of a theoretical or informational or physical trace not found on Earth would be a good start.

Uh, putting a giant 'thought' in people's heads is not evidence of alien visitation. We already have the ability to beam sound waves at people such that they feel as though there are external thoughts being put in their minds - (in fact, it's being used for advertising in some places).

We have have to be very careful and introspective about what we accept as solid evidence.

AND, it doesn't mean that 'skeptics' are hard to convince - it just shows a good understanding of how apparent information can be hoaxed or misunderstood or misinterpreted, especially the way human perception works.

To recap:
1. Pick specific verifiable information such as a math proof, or technology that is just beyond our means (maybe a few 100 years);
2. Realize it's all evidence, not proof;
3. Understand the limits of human perception;
4. Discern between 'high-strangeness' and 'solid evidence' of non-human, non-terrestrial visitation, right now.

Hope this clarifies my position.

Sorry, guys, I just don't understand this 'boo-hoo' no meanie-pants skeptics will believe us schtick.

Of course skeptics will believe solid evidence and all the crying about someone not believing a 'story' is just silly.

No amount of boo-hooing and crying elevates these stories and fuzzy 'blobsquatches' to the level of evidence of non-human, non-terrestrial visitation, no matter how much we'd all like it.