First Earth-Like Exoplanet Found!!!

Artist's Impression of Gliese 581 System

This has to be one of the most exciting things I've heard in years. Astronomers in Chile have found the first ever Earth-Like Exoplanet! This is the first time we have evidence for our hopes that our Earth is not the only habitable planet.
The planet, Gliese 581 C, goes around an M dwarf (see diagram in previous post for classification clarification) star at a very tight radius with a year of only 13 Earth days. It is 50% bigger than the Earth and is five times heavier. The system is 20 light years away.


Gliese 581, the M dwarf around which the planet orbits

This is exciting because it is the first planet we have ever seen (besides Earth) that can support liquid water. The temperatures are a bit higher than here on Earth but not too different (between 0-40 degrees Celsius). This is assuming an Earth-like atmosphere, which may not be the case. The proposition is that this world is either a rocky planet or one that is completely dominated by water and oceans.
This is exactly the kind of planet SETI expects to find intelligent life on. After two sweeps a couple of years ago they didn't find anything but I'm sure they will be looking again, this time much more carefully. I'll be stepping up my SETI@Home dedication in the mean time. Even if it's not occupied, then it may be our home far in the future, when we've finished pillaging the Earth.

Solar System Podcast

Podcast Stream:



Some of the stuff I mentioned:


Herzprung-Russell Diagram


Diagram of the outer extent of the solar wind

For a scale model of the solar system check this out.

Music this episode was We are Electric by the Flying Steps.

Gagarin and Special Relativity Podcast

Podcast Stream:



First thing I have for you is a real treat. This is Feynman's Lecture on Special Relativity. Listen to this for a deeper understanding of the subject.



A couple of corrections and stuff:

-Gagarin died at 34, not in his late 30's or early 40's as I suggested.
-The Speed of Light is 186,000 mi/s, as I tentatively proposed.
-Every time I said the word "moving" without the word "relative" right after it, it should have killed your soul a little bit. Sorry about that. You fill in the blanks with what makes sense and heal your soul. :)

Demystifying Special Relativity, Part 2

OK, so we know what the theory of Special Relativity says. Now I want to examine some of the consequences that arise. Please understand that Special Relativity and it's effects are not things that we normally feel on a day to day basis. This is because neither we nor anything that we (unless you're in some specialized profession) care about moves anywhere near the speed of light relative to anything that matters to us. This is what makes the ideas of Special Relativity seem so crazy sometimes. We need to stretch our common sense notions of space and time, in order to really get a grasp of the theory and its effects.

Time Dilation

Imagine a clock like the one shown below. It has a light source on the bottom, a mirror on top, and a detector on the bottom to detect the signal when the light comes back down. So the time for it to go up and down is the twice the height of the light clock divided by the speed of light, c.
Now imagine that the light clock is moving relative to you. You would see the light follow a triangular path, like that shown in the second picture in the series below.



Basic trigonometry and the Pythagorean theorem will inform you that the distance from the detector to the mirror and back in your reference frame is greater than that in the proper frame of the clock. Proper is just a word that means in the rest frame. So now we know that the distance traveled for the light to get back to the detector in a non-proper frame of the clock is larger than in the proper frame of the clock. We also know, from the laws of electromagnetism, that light travels at speed c, always. So, we have the same speed and a larger distance. Because time elapsed is inversely proportional to velocity and directly proportional to distance, as distance increases, time elapsed also increases.

The time elapsed in a reference frame moving with respect to an observer is longer than that elapsed in the proper frame of the observer. When something moves and an observer looks at the moving thing, he sees time go by slower in the moving thing.

Note: Everything seems normal to the moving guy. In the guy's proper frame everything is just like it would be if he was in any other uniform state of motion.
Note: The Light Clock used above is just an example. Time dilation is not some unique effect of the light clock, nor is it just an effect of clocks in general. Time dilation is a property of space-time, which is the framework of our universe.

In the next entry I'll discuss length(Lorentz) contraction and start discussing what space-time is.

Demystifying Special Relativity, Part 1

This is the first part of what will be a multi-part series on Einstein's Special Relativity, which is probably the single most important law for understanding modern Physics and one that is not as complicated as some people think. I'll try to avoid the math here; after all, this is a Physics blog, and Physics is primarily about concepts.
I'm putting a few entries on relativity here because I feel like you need to understand it in order to really understand most of the news entries about modern Physics and Astronomy I will be posting. I know you can read all this information off of Wikipedia and other sources, but I'll try to make it more digestible for non-scientists and you can leave comments if you have any questions.

Galileo: The first principle of Relativity


Galileo's sketch of Jupiter and some of it's moons orbiting it, showing that not every celestial body goes directly around the Earth

Galileo was the first person to propose a theory of relativity. His theory of relativity (sometimes called Galilean Invariance) basically states the following

Newton's laws hold in all inertial reference frames

Let's look at this carefully. Newton's laws are the basic laws of mechanics and kinematics. I'm not going to go in depth into what these laws are but you check them out in more detail here.
An inertial reference frame is one that is moving at a constant velocity. That is, it has a constant speed and a constant direction.
An example of what Galileo's Principle says is that if you are playing table tennis on an inertial train, the game will have to follow the same rules of Physics as a table tennis game played on the ground that the train is moving relative to. This idea of relative motion is really important in both Galilean and Special Relativity. This is because relativity implies that there is no absolute state of motion. If you are on the train traveling at speed v relative to the ground, are you the one who is moving or is the person on the ground you see moving past you at speed v? From your perspective, the guy on the ground is moving at speed v away from you. That's your frame of reference in this situation. From the ground the guy think you are moving at speed v. So, the important point is that there is no absolute motion.
So that is the original principal of relativity. That's it.

Einstein's Great Idea
So what was Einstein's ingenious idea that makes most people think that this theory is so hard? What is the incomprehensible, fantastically amazing, conjecture that Einstein made.

Galilean Relativity said that the laws of motion were the same for all inertial reference frames. Einstein's Special Relativity says that the laws of motion and all other laws of Physics were the same in all reference frames.

That's it. Most of the weird consequences that pop out of Special Relativity come from one law of Electromagnetism. That law is:

Electromagnetic Radiation (including visible light) travels at speed c=299,792,458 m/s=670,616,629.384 miles per hour

Scale model of light traveling from Earth to Moon; the time for light to get there is correct.

The law of special relativity is not so much about things being relative as it is about one thing being constant (the speed of electromagnetic radiation). In order to keep this quantity constant, the static character of space and time has to be given up. In other words, space and time have to change so that the speed of light doesn't change. I will explain how they do this in the next post.

I think that's enough for today. Think about that and I'll continue this ASAP.

Voyager: Our Bottle in the Cosmic Ocean

"...the launching of this bottle into the cosmic ocean says something very hopeful about life on this planet." Carl Sagan on the Voyager 1

I mentioned in the podcast yesterday the Voyager spacecraft, which was sent into space in 1977 and which is now further out than the orbit of Pluto. I know I promised real hard science but I feel like the story of this craft is really inspiring and thought provoking.

Voyager 1

The Voyager spacecraft carried a golden record containing various images and sounds from the Earth and from our civilization. This "Golden Record" is really amazing and deserves some attention. Most of all, the idea of representing humanity as one united civilization is one that gives me a lot of hope for the future.

The Golden Record, which was onboard Voyager 1

What's all the gibberish on the front of the record?

I'll let the official NASA documentation explain all this. It's really fascinating to think about how to communicate with beings that may be completely different from us. Some really smart people worked up a way to try to give the beings instructions for playing the record.



How do we represent ourselves to these beings?

I feel like this is the really interesting question that this record and the Voyager mission brings to light. In the midst of the Cold War, all of humanity took it upon themselves to present a united front to any being that will find this record in the distant future. We weren't trying to represent America, or the USSR, or any specific people or country as special. For the first time in the history of humanity, we had to think about ourselves as one, united species.

This is a message on the record from the Secretary General of the United Nations at the time, Kurt Waldheim:

"As the Secretary General of the United Nations, an organizations of the 147 member states who represent almost all of the human inhabitants of the planet earth. I send greetings on behalf of the people of our planet. We step out of our solar system into the universe seeking only peace and friendship, to teach if we are called upon, to be taught if we are fortunate. We know full well that our planet and all its inhabitants are but a small part of the immense universe that surrounds us and it is with humility and hope that we take this step."

What a beautiful message! I love the idea of people being able to think of themselves as human inhabitants of the planet Earth, instead of just Germans, Russians, Americans, etc.

Here is a message from US President at the time Jimmy Carter:

"We cast this message into the cosmos . . . Of the 200 billion stars in the Milky Way galaxy, some - - perhaps many - - may have inhabited planet and space faring civilizations. If one such civilization intercepts Voyager and can understand these recorded contents, here is our message: We are trying to survive our time so we may live into yours. We hope some day, having solved the problems we face, to join a community of Galactic Civilizations. This record represents our hope and our determination and our goodwill in a vast and awesome universe."

Community of Galactic Civilizations? I don't think I need to say how touching these messages are.

There were also visual and audio representations of human civilization on the record. I'll leave you with some of my favorites and a link where you can see all of the rest of them. As you look at these pictures, be proud to think of yourself not as a German, Russian, American, etc., but as a human being.


Diagram of Vertebrate Evolution






UN Building at Night



See the rest of the images and hear how we want to represent our civilization and our world through audio here.