A Day Without Satellites

The BBC has a short fictional piece about what would happen if all the world’s satellites stopped working. While that is unlikely, it’s an interesting look at how much satellites are integrated into everyday technology. For instance, while the Internet is mostly an Earth-based affair with undersea cables connecting continents, I didn’t know that that the atomic clocks on GPS satellites were used by data centers and Internet exchange points to timestamp Internet data packets. One thing I’m a bit confused by is how much the article claims international telephone calls would be disrupted. I could see things like aid workers and military units who are in areas with little landline or mobile infrastructure being affected, but I thought most international calls on landlines and regular cell phones were done through the undersea cable network.

While this article may be drastic, it is important to note that our satellites are increasingly at risk of damage and it’s an issue that increasingly concerns industry and governments.


Revising the Universe

This week, scientists affiliated with the European Space Agency’s Planck observatory announced several discoveries from the first 15 months of Planck observations. Planck observes the cosmic microwave background (CMB) radiation. The CMB is the oldest light we can observe in the universe (from about 380,000 years after the Big Bang), because it comes from the time when neutral atoms finally formed and stabilized and photons were no longer constantly absorbed by free electrons and protons. Because of it’s age, studying the CMB enables astronomers and cosmologists to look at the early structure of the universe.

The newly released Planck data contains a few surprises, some vindications of previous work, and many things that are a mix of both. One of the things I found most interesting was the newly calculated age of the universe. Based on the Planck observations alone, the team predicts the age of the universe to be about 13.82 billion years. What’s great about this is that it falls exactly within the resolution of the previously predicted age of the universe by NASA’s WMAP data, 13.73 billion years +/- 0.12 billion. The error bars on the WMAP data mean that anything within 0.12 billion (120 million) years of each other is pretty much indistinguishable from each other. That the Planck data falls within in it means our observations and models seem to be very good at describing the universe.

What’s even more interesting (at least to me), is the stuff that doesn’t entirely jibe with our understanding of the universe. Sure, the age is a bit different because of a change in when dark energy is believed to kick in (the force that is causing the accelerating expansion of the universe that was discovered in the late 90s), but the slight change is practically bookkeeping compared to the other things. When discussing fundamental physics, I mentioned one major kink in our theories is that there seem to “preferred” directions for giant globs of stuff to clump together in the universe. The Planck data shows many deviations from randomness that WMAP found still hold and weren’t just caused by limits in WMAP’s data.

So what do we have?  The big deal is that the universe seems to be off-balance. If you look at the image below, comparing Planck’s data to the model, the left and right side seem to have different brightness. Since the brightness of the CMB is related to where mass would accumulate, this would also mean there’s more stuff in one half of the universe than the other, based on what we can see. It’s also worth noting that Plait says the distribution of hot and cold spots still seems random; it’s just the intensity that isn’t.

Image of deviations of Planck’s data from the standard cosmological model. Credit: ESA and the Planck Collaboration

Another quirk is the so-called CMB cold spot, a region initially found in WMAP data that was both larger and colder than expected for a random distribution. In recent years, some people challenged its existence and said its uniqueness might be due to how WMAP’s data was analyzed, but it still holds up in the Planck data release (although I can’t find out if the Planck team used the same statistical analysis as WMAP, so the Michigan scientists might still have a point).

So what do these mean? Well, a popular theory for each of these that these are “imprints” from another universe. If you’ve heard anything about string theory, you probably know that it requires the existence of many other dimensions (10 or 11, typically, depending on the exact form). In some versions of string theory, our 4D (3D-space + 1D time) universe can move around in this higher-dimensional space called the bulk and it could also potentially interact with other universes.

This’ll be an exciting time for cosmologists and physicists as they try to reconcile their theories with the new observations.

PS: I can’t find if Planck shows anything about the “axis of evil” alignment or dark flow, which are other interesting structural observations. But both of them depend on large scale surveys like Planck (and dark flow was specifically based on CMB data), so I could see these being looked as people have more time to process the released data.

Smallest Exoplanet Found

Astronomers recently announced finding a new exoplanet (a planet in another solar system). That alone wouldn’t be a big deal anymore, since in the last 20 or so years we’ve found more than 800 (with a few thousand other “candidates” requiring more study to verify). What’s special about this one is how small it is. Newly discovered Kebler-37b is only 3865 diameters wide, making it smaller than Mercury and barely larger than the Moon.

Aside from setting a new record for smallness, it also represented a unique experiment. Kepler-37, the star the planet orbits, has not been studied much and so astronomers were uncertain of its size (both volume and mass, is my understanding). One way to determine this is seeing how the stellar equivalent of seismic waves behave in the stars interior (a discipline called “asteroseismology“). It turns out that for most stars, the way it oscillates is also linked to its size. You might wonder how this is possible since, on Earth, seismology is a fairly hands on affair with detectors everywhere. With stars, we can look at their light. If you split the light from a star into all the colors (giving you a “spectrum”), you’ll see dark lines appear at some spots.

Spectrum of the sun

These dark lines are where the light is absorbed by the atoms in the star. If you have really sensitive equipment to read the spectrum, you’ll see that these lines actually move slightly over time. This is because of that ubiquitous feature of waves, the Doppler effect. Just like an ambulance siren sounds higher pitched when approaching you and deeper when it passes you and moves away, light does the same thing. So if a segment of a star is expanding toward you when the light is emitted, we see the spectral lines at higher frequencies (or “blueshifted” as it moves closer to the blue end of light) and a shrinking section has lines at lower frequencies (or “redshifted”).

The other cool thing about this discovery was who funded it. The asteroseismology work was not funded by NASA, but actually by a crowdfunding project called Pale Blue Dot. The organization has people “adopt a star”, but instead of pretending to let you name it and making you pay for an expensive diploma (*hem hem*), the money star adopters give goes to fund research groups working with data from the Kepler mission.

Physics Education, in a Bit More than a Minute

MinutePhysics, an extremely popular YouTube channel that explains physics topics (though typically in a bit more than a minute), posted an “open letter to President Obama” about reforming high school physics.  Here’s the video, and my thoughts are below.

I actually have conflicting feelings about this. First, I would point out we do cover some of that, but not in physics. In my district, the Big Bang and astronomy were covered in an “integrated science” class on Earth and space science and some basic physics. And for some weird historical reason, we’ve decided that atomic structure is a chemistry topic until you get to college (I calculated the energy of nuclear mass defects in my first high school chemistry class, and that is straight-up E=mc^2) while high school physics is just elementary mechanics and E&M, probably out of some combination of bureaucratic inertia and a view of what was considered “practical” when these curricula were standardized. 

I honestly think the way we teach physics and chemistry in high school now prevents us from adequately covering modern physics. Quantum mechanics doesn’t really have any conceptual overlap with mechanics at this basic level and so it’s hard to integrate into the physics curriculum. This is also the view of some of advocates of a so called “Physics First” curriculum; the standard curricular divisions of high school biology, chemistry, and physics don’t really make sense given the way modern science works. One group advocated just really trying to integrate all three subjects and just have a three-year science sequence that isn’t separated as much by field. That would help remove any potential turf war between what parts of atoms are physics or chemistry and what biochemistry is biology or chemistry.

As an aside, relativity actually seems like it would be doable in high school. Or at least the only bit we cover in undergrad physics.  The Lorentz transformation is just algebra, and honestly that’s enough to help you understand a lot of its relevance to life (GPS correction, length contraction, etc). If I could propose one dramatic change to how we approach high school physics, I would honestly be okay with less emphasis on modern physics and more on just the general idea of energy. Physics (and really all of nature) is about minimizing energy.

BANG! POW! Straight to the Moon(s)

The Economist had two great piecees last week about why moons may be the next big thing in the search for life.  The articles are wonderful, and I highly recommend that you read both of them.  And also highly recommend The Economist as a place for science news.  They are one of the few general newspapers/news magazines  where I think nearly all their science and technology articles are well written.  My only complaint is they don’t always have articles I find interesting.

The one thing I’d like to expand on a bit is our poor (or at least, I think so) definition of the “habitable zone”, or if you watched Battleship this summer, you might also be familiar with the other name for of “Goldilocks planet“.  Currently, if you hear someone talking about a habitable zone, they probably mean one thing:  the region where a planet can orbit a star and maintain liquid water.  But that actually is a really vague definition.  A lot of this also depends on the planet you’re looking at.  How much light a planet reflects is a big factor in how much heat it can keep.  (In fact, Ice Ages are feedback loops because of this – the ice caps are really shiny compared to dirty and water and can reflect off a lot of heat and prevent their melting, leading to more ice and less heat)  And we need to consider the composition of the planet.  Without the greenhouse effect of carbon and the salt content of our oceans, Earth’s water would freeze over a lot more often.  Of course, there are still ways to control for this.  People typically define the properties of a hypothetical planet they look at when calculating habitable zones.  And generally, there is a limit to where you can put something a certain star and expect liquid water (Mercury’s position would be a no-go, unless you were dealing with some particularly crazy atmospheres I think).

But that’s not what bothers me.  It’s that while some form of habitable zone/Goldilocks planet has gone on to permeate the broader culture, we’ve also kind of forgot to explain how this is an oversimplification.  Like the first article mentions, we expect water on lots of moons on planets outside the habitable zone because of tidal or magnetic heating.  And we could probably use better explanations of why NASA’s focus for astrobiology is to “follow the water”.  Even though I do worry about “carbon chauvinism“, there are good reasons people expect life to use water and carbon instead of other biochemistries.

Tweets from Space

In honor of the Curiosity rover landing on Mars in less than 24 hours (knock on wood), why not check in on its tweets to see how it feels?  You read that right.  NASA has set up a Twitter account for the Curiosity rover.  I was about to declare this the first ever official Twitter for a scientific experiment (while CERN has an account, it’s for the entire organization, and all the LHC accounts are made by enthusiasts).  However, it turns out Mars tweets are old hat for NASA, which set up an account for the Phoenix mission back in 2008.

Since robotic intelligence is not advanced enough yet for space rovers to actually talk to us, @MarsPhoenix and @MarsCuriosity are actually run by NASA’s social media team.  But it looks like they hope to have updates in almost real time as Curiosity gets ready for major milestones (at posting time, Curiosity last reported getting closer to Mars than the moon is to Earth).

I think these Twitter accounts are great moves by NASA.  Twitter’s character limit is a great way to send bite-sized mission updates to the broader public, and judging by its follower count, people love it.  Sometimes science in social media gets a bit of flak (I remember a few people saying the CDC’s zombie comic was a money waster), but I’m all for new ways to reach out to the public.  Important results should be vetted by peers before we accept things as fact, and the CDC comic was really only super helpful if you read the emergency preparedness guide with it, but there’s nothing wrong with getting people to care about this stuff in the first place by giving them a taste of excitement.

Hat tip:  Mars Orbited Adjusts, Rover Gets Twitter Account from Greg Laden on Science Blogs