One of the things I found most interesting is that Jesus used the word hell, but when he used the word hell, he was referring to an actual place in the city of Jerusalem in the first century.

The word he used was the word Gehenna and Gehenna means the Valley of Hinnom.

And the Valley of Hinnom was the South Valley on the south wall of the city of Jerusalem.

That's where people toss their trash.

So he's pretty much the only person who used it.

And when he used this word, he was referring to a real place where this trash was burning.

So essentially, he was saying, you as a human being, you have this power to make choices about whether you will move towards others in grace and compassion and kindness, or you will move towards people in violence and degradation.

And when you do that, when you mistreat others, when you are indifferent to their suffering, you're essentially creating a Gehenna on Earth.

And so you're creating a hell on Earth.

The idea that has animated a lot of religion for a lot of people, that there is some divine being somewhere who if you don't say or do or pray or believe the right thing is going to send you to hell.

Life is difficult enough without believing that the deepest, strongest forces of the universe are against you and are going to torture you forever.

Everybody is going to die.

I have never met anyone who is not going to die.

I've never met anyone who is of a certain age who's not already dead.

It sucks!

Now here's the evidence for why I don't believe in an afterlife.

It would be a fine thing if you could If I could have the capabilities, athletically, that I had when I was say 23, with the life experience and intellect that I have right now, that'd be fantastic.

And then live forever?

I say, bring it on.

But my beloved grandmother who was brilliant didn't have that happen.

She faded away, losing her faculties as she went.

People my age have a lot of grandparents and parents who are not as sharp, certainly not as athletically capable or physically capable as they were when they were younger.

And so watching ourselves die is to me, overwhelming evidence that there is no life after death.

There's certainly no—it doesn't seem to be any reason to think that when you die, you go back to your optimum age at your optimum athletic ability in your optimum intellectual sharpness.

And if it turns out that that's true, then you do die and have all this intellectual sharpness and athletic ability, cool, bring it on.

That'll be great, but what would you do differently?

What would you do differently if you knew for sure that you were going to be immortal when you died somehow?

Would you start committing crimes?

Would you jump off a cliff so that you can hurry to your immortality optimal state?

I just don't think so.

Instead, the finite length of our life is what drives us.

It's what makes us go.

And it's what makes you try to accomplish things or decide to have kids or not have kids or decide to live in another country, on another continent or not or decide how to invest your money or what you're going to do with your resources.

All of this is driven by the limited length of life we have.

So furthermore, if evolution is, in fact, how the world works—and it absolutely seems to be, from my point of view—one of the fundamental things about evolution that is so troubling is this whole idea of survival of the fittest.

That's really a 19th-century usage, a British usage of that expression: fittest.

It doesn't mean that you're able to do the most weightlifting or run the fastest 1500 meters or something.

It means you fit in the best.

And the troubling, troubling consequence of this is you don't have to be perfect or a super person.

You just have to be good enough from an evolutionary standpoint.

You just have to be good enough to pass your genes on.

After that, evolution, if it were an entity, doesn't really care about you, man.

You had your kids, your genes are passed on and you expire.

You lose your faculties as you run out of steam and that's just how it is.

Evolution, certain diseases catch up with you.

Certain auto-immune problems show up, certain viruses and bacteria, parasites get you.

Nature doesn't care.

You were good enough.

And so I encourage you to live your life as best you can every day.

And as far as putting my brain in an electronic receptacle for all time, it sounds great, but I will evaluate it on a case by case basis.

Do you want to be stuck in an Apple product the rest of your life or do you want to be stuck in a Microsoft product?

It's a tough call.

I'm sure books will be written, we'll see.

Digital and genetic immortality are within reach.

Already in Silicon Valley, there are companies, which for a price, will digitize everything known about you: your credit card transactions, your emails, Instagrams, everything known about you can be digitized.

And we have something called the Connectome Project which will map the pathways of the entire human brain, all your memories, all your quirks, personalities, everything digitized, and we'll put it on a disc and for the most part, we'll put it in a library.

Today, you go to the library and you take a book out about Winston Churchill.

In the future, you'll go to the library and talk to Winston Churchill because all his speeches, his mannerisms, his memories, his letters have been digitized.

I would love to talk to Einstein.

I would love to talk to him, even if it's a computer program that has digitized everything known about him: his work, his writings, his speeches, everything, and a holographic image so that I can talk to him.

And one day we might be digitized as well.

We'll be able to talk to our great, great, great, great, great-grandkids.

And they'll be able to talk to their great, great, great, great-ancestors as well because we become immortal.