# Tag Archives: Galileo Galilei

## SR #4: Two Rules

It’s Friday, and I’m sure you’re thinking about the weekend, so today will be just a review and some more details about the speed of light.

And speaking of light, today is the Vernal Equinox. For the next six months (for those of us in the northern hemisphere), our days will be longer than our nights. No doubt the combination of spring, the Equinox, and the weekend, have you wondering what you’re doing at your computer reading about Special Relativity.

So I’ll try to be very brief…

## SR #3: Relative Velocity

Throwing like a girl!

I’ve introduced the idea of an inertial frame of reference. This is when we, and objects in our frame, are either standing still or moving with constant (straight-line) motion. In this situation, we can’t tell if we’re really moving or standing still relative to some other frame of reference. In fact, the question is meaningless.

I’ve also introduced the idea that objects moving within our frame — moving (or standing still) along with us, but also moving from our perspective — move differently from the perspective of other frames. Specifically, the speed appears different.

Now I’ll dig deeper into that and introduce a crucial exception.

## SR #2: Relative Motion

In the last two posts I’ve explained how Special Relativity is about relative motion between two frames of reference, and that the motion involved is constant, straight line motion that allows us to view either frame as the “moving” one or the “standing still” one.

Today I’m going to dig a little bit deeper into the idea of relative motion and what that involves for actions within a constantly moving frame of reference versus what observers in a different frame perceive. In other words: trains, planes, and automobiles.

(Warning: this gets a little math-y, but you can ignore those bits.)

## Science is Easy!

No doubt those who regard quantum physics or Einstein’s relativity or even just trigonometry as an impenetrable thicket of unknowable terms and ideas have a hard time believing science could be easy. The lingo alone seems to create an exclusive “members only” club.

The trick is: easy (or difficult) compared to what? Many scientists now disdain philosophy (apparently forgetting what we now call science was once called natural philosophy). They point to the advances of science in the last 500 (or whatever) years and then say that philosophy hasn’t been nearly as successful in 2000 years.

But that’s because science is easy. It’s philosophy that’s hard!