## Wednesday, 7 September 2011

### Close to 1

In a quantum mechanics lecture last year, the subject of relative values came up. My lecturer said that a certain value was close to 1 then said in this example it was 2. To which one of the other students seemed quite confused and remarked about how he(my lecturer) had just said it was close to 1 to which my lecturer replied 2 is close to 1 it's not like it's a 1,000 or a 1,000,000. A bit of background my lecturer like pretty much all the lecturers at keele is an astronomer so he deals with very large numbers most of the time.

Now it might sound like the student was being very silly but thinking back at it there are an infinite number of values between 1 and 2 but you could say that about any value. I just thought it was interesting to think about the scales of numbers and how to say some value is close to another depends heavily on the context.

## Sunday, 4 September 2011

### Definition of a Planet

A Planet must...
• Obit around a Star
• Be sufficiently large that it's self gravity can overcome rigid body forces (it's nearly round).
• Have cleared the area around it's orbit from debris

It is the last bullet point that means Pluto is not a planet.

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