(Intro)

Hank: Astronauts get to do a lot of unusual things like go to space and orbit Earth at 21,000 km per hour, and on August 10th, three of the International Space Station's crew did something even less typical.  They ate space-grown vegetables.  This isn't the first time food's been grown in space.  The Russian space station MIR had its own greenhouse and everything, but this is the first time orbiting astronauts have eaten it.  It was a type of red romaine lettuce called "Outredgeous", which, according to astronaut Scott Kelly, "Tasted kind of like arugula."  

But growing plants in orbit is tricky.  For one thing, you have to make sure that the water and soil don't float away, but you also need to teach the plant which way is up, because it isn't getting its usual cues like the pull of gravity.  So the lettuce was planted in what are known as "plant pillows", basically bags of soil with wicks in them.  The bags kept the soil in place and the wicks guided the water into the soil.  Then, the seeds were carefully attached to the wick so that their root growing side was facing the soil.  The other shoot growing side of the seed faced a panel of red and blue lights, since those are the colors plants use to grow, and grow they did!

The first batch was planted in May of 2014, and harvested after 33 days.  It looked like perfectly normal red lettuce, but NASA wasn't taking any chances with unexpected space growing side effects, so that crop was frozen and then sent back to Earth for analysis.  It seemed fine, so the second batch was planted last month in July and it was also allowed to grow for 33 days, and then the astronauts harvested it.  They froze half the crop, which will be sent back to Earth for more testing.  The other half, though, they got to eat, though they had to wipe down the leaves with citric acid first, so they probably tasted a little more lemony than your standard Earth-grown lettuce.  

Researchers are hoping that learning how to grow plants on the ISS will help us grow plants in extreme environments here on Earth, like where there's very little water available.  Plus, growing food could be useful for long-term missions, like to Mars, since they'd have to carry less of the freeze-dried stuff.  Meanwhile, the researchers point out there might be psychological benefits for the crew, both from taking care of the growing plants and from having fresh food around.  In other words, space farming could just make astronauts happier.  

But you know what tends to make astronomers happy?  Discovering new things in space, and one recent find published in the monthly notices of the Royal Astronomical Society is the latest in a series of challenges to the way we understand the universe.  A group of Hungarian and American researchers discovered what looks to be a ring of galaxies but at five billion light-years across.  It's just too big to make any sense.  The team analyzed a set of 361 gamma ray bursts, or GRBs, the sudden bursts of energy that scientists think blast out of massive stars if they collapse into black holes.  GRBs are useful because we can figure out how far away they and their host galaxies are based on how fast they're moving away from Earth.  They found that 9 of the GRBs in the sample are roughly at the same distance, 7 billion light years, and together, their home galaxies form a huge ring connected by gravitational forces.  According to their analysis, there's only a 1 in 20,000 chance that this is a coincidence.  It's much more likely that the ring is a high-level way for the universe to organize itself.  
The thing is, huge structures like this go against what's known as the cosmological principle, which says that on the largest scales, matter in the universe should be evenly distributed, since forces are evenly distributed.  If you do the math, it turns out that we shouldn't be seeing any connections over more than 1.2 billion light years of space.  But this isn't the first evidence against that idea.  For instance, the supervoid, a low-density area of the universe, is 1.8 billion light years across, and another string of galaxies discovered in 2013 is 10 billion light years long.  

What does all this mean for the cosmological principle?  Well, it's possible that it's just wrong, since we don't yet have a theory of everything, a way to connect all of physics under one set of scientific laws.  If we had one, it might affect the way that we describe forces and change the cosmological principle.  But for now, the universe's biggest structures are also some of its biggest mysteries.  

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