This is a story about changing beliefs...
Imagine being marooned on a rock in the middle of a vast ocean that's so deadly to life that you couldn't survive for more than a few seconds if you fell in. The ocean is lifeless and has no utility: it can't be purified or harnessed to generate energy. The rock has a fragile ecosystem that keeps you alive, but there is a relentless wind that threatens to blow away all the life-giving nutrients at any moment. You don't know how you got there, why you're there, or how the hell you're going to get off the rock if it can no longer keep you alive.
Welcome to the world according to science.
Isn't it much nicer to imagine an anthropocentric world, where some kind of paradise was created by an imaginary sky monster, just for us. Imagine there's some invisible guiding hand, making things happen, always with us Earthlings in mind. Imagine there's an all-seeing eye that only gives a shit about one particular species on one particular planet. Imagine that this universe isn't all there is: there's also some kind of afterlife. There... that's much more comforting, isn't it?
You could say that scientists believe in nothing. They don't think we were put on Earth for a reason: it's just a cosmic accident. Energy condensed into matter; quarks combined into protons and neutrons, which were fused into atomic nucleii; atoms bonded into molecules and reacted to create amino acids and proteins; the primordial soup created life, through pure chance. There's no reason for us to be here, except that given enough time - 14 billion years ought to do it - life as we know it becomes inevitable, given the laws of physics laid down at the birth of the universe.
When you start to study cosmology, you get some perspective on just how insignificant we are. When you start to deal with things on a cosmological scale, the numbers boggle your mind. There aren't even rulers that can measure the distances between objects in the night sky, because space and time are warped by matter and energy. Things are so far away, and we only have a tiny planet to move around on, so it's not like we can triangulate the position of anything. Everything in the universe appears to be just a point in space to us: the twinkling dots of light in the night sky.
If you think about time and evolution, you begin to see the staggering number of living creatures that died - our ancestors - so that we could be alive today in our current form. Take a look at an ear: it's a fucking weird looking thing, isn't it? Why the hell would it look like that? I can't tell you, but I know that I can take a shower without getting water in my ear canal, which is pretty awesome for listening out for any approaching sabre-tooth tigers while I'm washing myself.
Then, what about consciousness? Why is it that you are you? Why were you were born at the exact moment you were born? Why are you alive, right now, and not a hundred years ago, or a few thousand years ago?
So far as you know, you're the only you. Everybody else is somebody else. You've got your own unique set of experiences. You've got your own unique set of senses, and your own consciousness processing the sight, sound, smell, touch and taste of everything around you.
Ultimately, we can reach the conclusion that each universe is actually tailored to a single individual. The reason why there are lots of other people around who look very much like you is an inevitable consequence of the universal laws of physics. If I tweak the numbers one teeny tiny bit, we might get an almost identical universe, but there's a different person whose mind is "the one" that is truly conscious.
You feel pretty conscious, don't you? You feel like you've got free will and memories and you're seeing the world, right now, for what it is. But, that's only in your own universe. In your universe, I have no free will or consciousness: my world is dictated by your actions. In your universe, I'm not deciding to write these words... I'm not even aware of what I'm doing, even though I think I am.
The test is this: what would happen if you killed yourself?
Right now, there are about 7 billion people in the world. If I was to kill myself, 7 billion people would agree that I was dead and buried. 7 billion people would say that I just killed myself. But what about me? What about my opinion?
Here's how it goes: I get a gun, aim it at my head and pull the trigger. Guns are pretty reliable these days, so lets say I have only a one in a million chance of surviving a point-blank gunshot wound to the head. This is my free will, right? I make the decision to commit suicide, because I'm a conscious being with free will and that's my prerogative to do so.
So, what happens if the gun misfires? What happens if I put the gun down, pick up a different gun and that one misfires too? What happens if I pick up a machine gun, aim it at my head, pull the trigger and it just goes click-click-click-click-click as it keeps misfiring?
Essentially, if you take our very best scientific theories and follow them to their inevitable conclusion, this is what is predicted. If you keep asking "why?" over and over again, until you get to the deepest possible understanding of the universe as we observe it, you will conclude - from reproducible experiment - that the world is influenced by us, as observers. Our very consciousness is inseparable from reality and the laws of physics.
It's quite possible to answer the question "why are we here?" with the answer: so you can ask that question.
That might sound like begging the question, but it's actually perfectly logical.
Without consciousness, the examination of the world around us is not possible. Arguably, without being conscious of the existence of the universe, does the universe really exist?
Taking this reasoning a stage further, you can start to argue whether anybody in the universe in which you inhabit has ever truly been conscious. The evidence would suggest that they haven't, given that they are not able to experience the universe as you do: they are not able to answer the quantum suicide paradox, so they are unable to prove or disprove the reality in which they inhabit.
You and you alone are truly conscious, and everybody else is just an inevitability of the laws of the universe: entropy will destroy anything so ordered and sophisticated as a conscious being like you, but once you get one (you) it's inevitable that there will be billions of knock-off copies that didn't quite make the grade in your universe.
Ultimately, you are immortal and you will witness the end of the universe. It's the only logical reason why you were born when you were born.
"But what about all those people who die before me?" I hear you ask.
Well, they were never really conscious. I'm sure that in their own universes, which were nearly identical to yours, they were perfectly conscious, but the one universe in which you live, is made just for you: you're going to witness the death of everything and everybody, even if you try to kill yourself.
Taking this a stage further, we then wander into the territory of the theological.
What about heaven and hell?
If you're immortal, how do you think the world's going to be shaped by your actions?
Once you realise you're immortal, are you going to be naughty or are you going to be nice?
How's anybody going to stop you doing anything you want, if they can't kill you? You might as well be a thief; you might as well rape and murder; you might as well take anything you want and enslave all of humanity. As you rape and pillage, the world will become scorched and barren: Hell on Earth.
Alternatively, you could live virtuously, impart your wisdom and not abuse the discovery of your immortality. You could influence the people of the world to look after their home planet and try to preserve it beyond the longevity of their mortal lives. Over time, the world will become a place where everybody benefits from the generation before them, and it becomes received wisdom that it's better to co-operate and act with restraint, rather than act selfishly: Heaven on Earth.
Thus, we have arrived at a scientific reason for morality, as well as the negative consequences for 'sinning'. Science has drawn the same ultimate conclusions as religion: don't be a dick.
The chances are our species will wipe itself out before we are able to terraform nearby planets. The idea we're all going to fuck off to Mars on one of Elon Musk's SpaceX rockets, is actually just a massive excuse to continue raping and pillaging. The billionaires think that they've got an escape capsule, so there's no reason to rein in the corporate excesses and end the inequality that's destroying the planet.
Scientifically and through historical study of past civilisations, we're utterly fucked. The pursuit of pacifism, debt forgiveness, abolishment of usury and the creation of a fair and equal global society, has been completely abandoned in favour of rape and pillage. Capitalism must inevitably lead to the destruction of the natural world, overpopulation and enslavement of the developing nations, in order to fulfil its insatiable demand for unnatural growth. Things can't grow forever on a planet of finite resources: the laws of physics say that we can't just magic all our problems away.
We're acting like a blackjack player who's got a score of 20 but asking for another card, hoping to get an ace. Chances are, we're going to bust.
I really don't want a Tesla electric car: I'd rather not have to go to my bullshit made-up job. I really don't want a rocket ride to Mars: I'd rather people in Africa had some bicycles. I really don't want a NutriBullet food blender: I'd rather we abolished economic policies that leave nations starving, while others waste vast quantities of food. I really don't want an iPhone 8: I'd rather not have wars over mineral resources needed to make throwaway electronic gadgets. I really don't want private schools and top universities: I'd rather educate young women so they can make smart family planning decisions.
Just remember where the fuck you are: you're floating on a rock in the vacuum of space, with an incredibly thin layer of atmosphere just clinging to the surface because of the extremely weak force of gravity. The only reason the air isn't blown away into space - leaving you suffocating - is because planet Earth has an iron core which generates a magnetic field, diverting away the solar wind. Only 29% of the planet is land, and the rest is salty water you can't drink or use to water the crops. Have some fucking humility.
"But I'm some hot-shot CEO of a massive global corporation"
Yeah, right buddy. Try counting your money while holding your breath.
"But Elon Musk is going to fly me to Mars"
Yeah, and what are you going to do when you get there, you fucktard? There's no breathable atmosphere. There's no fertile soil.
"Scientists and engineers will find a way"
You mean the guys and girls who are telling you that the climate is fucked?
"God will guide us"
Good luck with that.