Jumping, saying hi

Finished reading The Discoveries last week. A recap of the major scientific discoveries of the 20th century, complete with the actual research papers, it plunged me back into my physics past.

It made me think about quantum physics and how it has really changed everyday life. Example: while for some medical imaging ultrasound is the way to go (including the echocardiogram and fetal imaging), to view the detailed inner workings of the organism you have to go CT—computed tomography. Three dimensional reconstructions of 2d x-ray slices.

And what’s an x-ray? High wavelength light being absorbed and reflected from different densities of materials, and a little fluorescence.

And what is fluorescence? A photon’s energy is transferred to an electron, kicking it into a higher energy state—usually followed by retransmission of the energy. It’s as if the electron is jumping, saying hi, then dropping back down.

I thought about this as I watched our dog Jefferson, an inveterate ladies’ dog, greet a crowd of teenage girls out for a walk tonight, as he stood on his hind legs, wagged his tail, barked once, and sat down again in the grass.