If the universe is expanding, what is it expanding into? It’s actually a great question, with a subtle answer. The universe doesn’t have to expand “into anything” if it doesn’t have an edge, in other words if it is infinitely large. Take a look at this Escher print of an infinite grid. As far as the eye can see, the grid goes on forever. Now imagine each of the sticks between nodes all getting longer. The nodes would begin to separate, and this Escher
universe would begin to expand. But it isn’t expanding into anything, it is just getting larger. That’s exactly the same as what we notice about our own universe. All the galaxies appear to be moving away from each other. But there is no edge to the universe, and therefore there also isn’t a center to the universe (which is also the reason the Big Bang didn’t happen at a point). At least we haven’t seen an edge yet.
Here’s another version I like of this print done by Escher. Flying fish as far as the eye can see!
Update 1/25/2012 – A reader wrote to inform me that these Escher works were not actually paintings, but rather prints. I’ve corrected the post.
Last week it was announced that our Milky Way Galaxy likely has more than 100 Billion Earth-like rocky planets. Many, if not most, stars in our neighborhood are likely to have at least one planet capable of supporting life. With so many habitable planets, why is it that we haven’t found any signs of intelligent life despite decades of searching? One possibility is that life is indeed out there, but there isn’t enough time between asteroid impacts for civilizations to become advanced enough to prevent being wiped out. Our planet is struck by an asteroid large enough to wipe out advanced civilization (roughly 1km or larger) about once per million years. This is not to be confused with the rarer and larger asteroids capable of causing most life to go extinct (10km or larger), but here we are talking only about those capable of “just” knocking out civilization. As civilizations become more advanced, they become in many ways more interconnected and fragile, like a complicated piece of machinery. Witness the global effects of such relatively minor events as the recent tsunami in Japan and the 2008 financial crisis. Any civilization must eventually develop the technology to predict and prevent asteroid impacts (and the foresight to use it), or it will eventually be ctl-alt-deleted back to a much more primitive state. Perhaps life does exist elsewhere, but hasn’t managed to pass this test. Human civilization is about 10 thousand years old, and we have just recently reached the stage of building rockets and space telescopes (the essential ingredients in finding and deflecting asteroids). Will we deploy the technology to find threatening asteroids and pass the test? Or will we continue to play the odds?
In the Silicon Valley rush to do everything fast, we often push things forward by “trying things out and seeing what happens”. There is a lot to be said for such a style – it drives innovation. At Google we called it a “bias towards action”. But sometimes, especially in a crisis, it just leads to churn. One of the things I learned as an astronaut at NASA is how (and when) not to hurry decisions. One of the old-head astronauts told me when I was new that “no situation is so bad that you can’t make it worse by acting too fast”. In fact, more often than not, if something didn’t kill you right away, you had time to gather some data and consider your options. If things were stable and a critical decision is needed, it often paid to wait for more data that could inform your decision.
In 2003, when we lost Space Shuttle Columbia, we still had 3 people in orbit aboard the International Space Station. But we knew we had no way to send sufficient supplies to keep the Space Station running indefinitely. Rather than abandon ship right away and bring the crew back down to Earth using the escape pod (Soyuz spacecraft), we calculated that we had a few weeks to make up our minds. During that time, we worked out that we could manage to keep the Space Station running with just 2 people, as long as we could train them quickly enough to fly another Soyuz up to the Station. When the word came back that this was just on the edge of being possible, I was informed on a Friday afternoon to get myself to Russia that weekend to begin training as a Soyuz flight-engineer (which was a story in and of itself!) The decision making was methodical and thorough, and the end result was that we managed to keep the program alive for several years in this manner with 2-person skeleton crews. Even now I have to remind myself that sometimes you can actually move faster by slowing down your decisions.
Some years back I was involved in a discussion of how much radiation shielding we needed to put on a spaceship for a manned mission to Mars. At issue was how to keep the expected risk from cancer down to a few percent. This required an enormous amount of shielding to be put on the spacecraft, to the point where it might actually increase the astronauts overall chance of dying because the spacecraft could become so heavy that the rocket was less reliable and other safety systems were compromised. This was crazy because we at the time were considering missions where the chance of dying because of a rocket failure somewhere during the 3 year voyage might be 50 percent. It was a bit like being overly concerned with a mountain climber eating too much unhealthy fatty foods for breakfast on the morning he is going to scale Mount Everest. We got carried away with the dangers of developing cancer over 30 years, and we lost sight of the fact that on such a mission our chief danger was in having a rocket or other system failure.
Sometimes the things we worry about aren’t the biggest threat.
Because asteroids have struck the Earth before, and they will again. In the latest Scientific American issue, I write about an awe-inspiring project to protect humanity. If we don’t find and track Near-Earth-Asteroids (ones that cross the Earth’s orbit), then we can never do anything about them. But if we have lots of advance warning – we have many options to divert an asteroid and prevent the impact.
I gave the keynote address at the 2011 CleanTech Open. There I saw lots of promising young
startup companies, and also the unveiling of the NASA Night Rover Challenge, a Centennial
Challenge contest for teams to develop a rover that can operate under battery power for a 14-day lunar
What is the largest unexplored area of Earth? Hint: It covers about 70
percent of the surface area of the Earth, and is blue, wet, and filled
with fish… Read more from my editorial in the Honolulu Star Advertiser here >>>
We are about to dispatch 4 robots from California that will swim across the Pacific (2 to Japan, and 2 to Australia). We’ll be taking scientific data along the way (temperature, composition, salinity, etc) and are inviting ocean scientists to make use of the data. For details, check out the contest website here. If you have a novel use for the data, or can address a new scientific problem using this data, we’d love to hear from you!