How big is big history? How do we think of human on cosmic scales? Well, only recently, we learned how old the universe is. It's roughly 13.8 billion years and to get some feeling of the magnitude of that timescale, we can use the metaphor of compressing the whole history of universe to a single year. If we would do that, then the universe would start at new year's eve with a big bang, but we only would see the first light from that cosmic explosion after 20 minutes. And then the first few months, everything would be dark and then spring the first class and galaxies would emerge. Our own Sun and the solar system would appear around September 1st, including the planet Earth and life on Earth would evolve pretty soon. By October, we would have bacteria. We would have single cellular life and kind of complex organisms, multicellular organisms like sponges would only appear midway through December. In fact, it's the last week of December that's really exciting. By Christmas, the dinosaurs would appear and they would be wiped out by December 30th. The last two days of the year would actually see the evolutions of mammals, as we know and other life forms. And us human beings, modern human beings, only appear at the very last six minutes of that year. Kind of regular history with written records and agricultural settlements would be the last 30 seconds of that year, and modern history from Columbus to the birth of the scientific revolution to all the wars would be the very lost seconds of that year. We think in terms of time scales, but we can also think in terms of space and then actually we can go on both directions. Human beings and everyday object are roughly midway between the very large structure of the universe as a whole, and the smallest structure of subatomic particles. In fact, if you think about stars on everyday scale. For instance, this great food could be a star, could be our own Sun. And then planet Earth would actually be one of these peppercorns, roughly a hundred times smaller. But in fact, to get a good feeling of the distances, at these scales, planet Earth, this little peppercorn would be at a distance of ten meters from the Sun, this grapefruit. And at these cosmic scales, light would move very slowly. In fact, it would take 8.5 minutes for light to traverse the distance from the Sun to the Earth. So one question is if this is the Sun, how far do you have to move to meet the next star, Alpha Centauri? Space is really empty if this is the Sun here in Amsterdam, then the next star will be in Russia. In fact, it will be Moscow. 3,000 kilometers further down and that's only the next star. In our Milky Way, there are a hundred billion stars. And to get a sense of that magnitude, you should think of a star now as a grain of sand and then the Milky Way would be a big pile of sand, roughly a few hundred billion stars and that's only our local galaxy. The universe, the visible universe, the part of the universe that we can see through our telescopes contains roughly a hundred and billion of these galaxies. So, a hundred billion piles of sand. That's only the part of the universe that we can see and it could very well be that the actual universe is much larger. In fact, it could even be infinite. If you go the other direction now and we think of space from the point of view of a subatomic particle, then we could think again of this grapefruit, but now would be the nucleus of an atom. In fact, an atom would have several of these grapefruits together and we could think you were here in Amsterdam, we could think of then as an atom as the size of the city of Amsterdam. So, it would have these grapefruits and then there would be a few electrons flying around through the city. On that scale, a cell the unit of biology say, think of the smallest human cell or a human blood cell would be roughly the size from the Earth to the Moon. And if we think about ourselves from the point of view of an elementary particle, we would be a thousand times big as from the distance from the Sun to the Earth. We would be bigger than the solar system. So from that perspective, we are both very small and our human history is just a minute fraction of the whole cosmic time scale. But from another perspective, we are actually big, because it's actually us humans living on this small planet Earth who figured out just in a few hundred years in this very last second of the cosmic year. The full evolution of this universe and it's us from this everyday space skills who have figured out both the largest structures in the universe, and the smallest particles. So from that prospective actually, I think we, as human beings can feel pretty big.