First of all, those are two completely different questions. What happens (presumably you mean after death?) doesn't necessarily have anything to do with why we are here.

It could be that nothing happens after death, but there is still some grand purpose to existence. Or it could be that there's an afterlife, but the universe itself is meaningless.

As to what do I really know? The answer is, of course, nothing. No-one can really know anything about what happens outside of our existence and anyone who tells you they do is either lying or delusional.

However we can make an educated guess (and not even a "so called" one, a real one based on centuries learning about the universe we inhabit) Every time we make a new discovery, it has turned out to have a natural explanation. As we learn more, the "god of the gaps" has grown smaller and smaller, to the point where we know that even if there is some mystical force underlying the universe, it has no measurable effect on it.

*related=http://videosift.com/video/Physicist-Sean-Carroll-refutes-supernatural-beliefs

If our consciousness really does continue after our physical bodies die, there has to be a mechanism for it, and there is zero evidence of any such mechanism.

It could be that we simply lack the tools or the understanding to detect this, but there isn't even anything leading us to ask the question (e.g. an unexplained phenomena that would prompt us to investigate a hypothesis that might lead to a theory).

As to why we are here? From a scientific point of view, there's no evidence to suggest there is a reason to anything. The universe just is. From a philosophical point of view, I've always liked Carl Sagan's idea that "we are a way for the cosmos to know itself".

TL;DR We really know nothing, but it's pretty unlikely that anything happens after death or that there is a reason we are here.

Physicist Sean Carroll refutes supernatural beliefs has been added as a related post - related requested by ChaosEngine.

I couldn't even make it to the full minute mark. I think the video posted and related where Sean Carroll responds to the idea of a fine tuned universe is a good response.

This video is likely made by the same sort of people who once argued that "just a few feet in either direction and life on Earth couldn't exist". Of course the Earth doesn't have a circular orbit, and our Sun's Goldilocks zone extends from just past Venus (Earth side) to past Mars. Leaving both Earth and Mars well within the habitable zone.

My bigger problem with the video is you are trying to get to point Z, and saying it had to go through A-Y first in specific order. This is an argument used frequently against Evolution. The huge odds you'd have to go through to get to a modern human in the time allowed is greatly against modern humans forming when they did. Problem is you are working from the end result back, rather than the starting point and going forward, and it you are also discounting some other forces of nature. I used to quote the mathematical problem myself when I was a Creationist, though an Old Earth one as I was long of the opinion that Young Earth Creationist make Christians look stupid.

I may be an atheist, but I have no problem with a God of the Gaps if people want to believe that. I however don't believe that Jehovah is that God (there's too much evidence against Him, such as the fact He couldn't or wouldn't reveal himself beyond a tiny little backwater tribe, not to people in the Americas or Asia or Europe, but to one tiny group of people, either He's a Racist, which makes Him unworthy of serving, or He's not any more real than any of the other so called Gods). Whatever, or Whomever may have kick-started the Universe into existence didn't do it for some divine plan for mankind. The arrogance that it takes to assume the Universe in all it's glory was created just to awe man, or for whatever other reasons related to man and our involvement with Jehovah is arrogance beyond belief.

EDIT: Perhaps the better related video would have been http://videosift.com/video/Pure-Imagination-1

*related=http://videosift.com/video/Meta-Physics-Hans-Halvorson-and-Sean-Carroll-at-Caltech

(Meta)Physics: Hans Halvorson and Sean Carroll at Caltech has been added as a related post - related requested by eric3579.

I think teaching students basic scientific method when they are young can prevent willful rejection of science, due to ignorance, later in life. Non-scientists can't possibly know everything, yet, if they are sufficiently enlightened in scientific method, they can comfortably accept truths that are revealed using scientific method. Additionally, scientists needn't require proof for knowledge widely accepted by the scientific communities outside their particular areas of expertise.

Specialization also eliminates the need to know everything. Scientists know they stand on the shoulders of giants, that there was much to discover and learn long before they arrived in the world. But they don't have to know everything. It's like Sean Carroll discusses (kind of) in this video. You can be a physicist and know little of geology.


Edited: clumsy, nonsensical sentences

Your video, Physicist Sean Carroll refutes supernatural beliefs, has made it into the Top 15 New Videos listing. Congratulations on your achievement. For your contribution you have been awarded 1 Power Point.

*related=http://videosift.com/video/Physicist-Sean-Carroll-refutes-supernatural-beliefs

Discovery Retreats: Dr. Sean Carroll on "What Inspires Him?" has been added as a related post - related requested by kulpims on that post.

Physicist Sean Carroll refutes supernatural beliefs has been added as a related post - related requested by kulpims.

part of a longer talk at Skepticon 5
*related=http://videosift.com/video/Sean-Carroll-Higgs-boson-fundamental-nature-of-reality

Physicist Sean Carroll refutes supernatural beliefs has been added as a related post - related requested by kulpims on that post.

Sean Carroll: Higgs boson & fundamental nature of reality has been added as a related post - related requested by kulpims.

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