Caleb A. Scharf

Even on Earth. And that is why we don’t see them, astrophysicist suggests: For example, could the messy chemistry we see in fossil fuels on Earth – a smorgasbord of organic reactions, a seemingly tarry chaos – be simply a short-term view of a living system that functions across hundreds of millions of years? Or consider a chunk of complex rock, a mixture of minerals and carbon chemistry. It may be bathed for a billion years in cosmic rays and indigenous particle radiation. It changes over that timescale, electrons are freed and captured, slow, slow chemistry and structural variation happens. Your pet rock might be just that, except you’re living too fast to notice. Of course, rather frustratingly, to make Read More ›

Recently, cosmologist Carlo Rovelli, author of The Order of Time, argued that time travel, especially into the future, can work. However, astrobiologist Caleb A. Scarf sees an insurmountable barrier, which he calls the “spatial problem”: Let’s take the Earth’s motion around the Sun. A month of orbit corresponds to moving in an arc of approximately 78 million kilometers. During that same period the entire solar system will have also moved approximately 600 million kilometers around our galaxy, and our entire Local Group of galaxies will have swept through about 1.7 billion kilometers of space relative to the cosmic microwave background. Not only do you need to traverse those kinds of distances, you need to get it correct to within a Read More ›