ET, stay home
Your excellent editorial in the April 24 issue of Science News (“An intelligent ET would probably just stay home”) explained the most obvious reasons for the unlikelihood of an extraterrestrial message, let alone visitors.

Additional obstacles worth mention are 1) the gigantic retro-rockets, parachutes and heat shields required for braking a super-speeding vehicle, and 2) the galactic power needed for aligning the astronomical egos of spaceship builders, launchers and captains.
Curtis L. Brown, Neenah, Wis.

Reading Tom Siegfried’s column on extraterrestrial intelligent civilizations raised an immediate question: Since it is highly likely that older societies with vastly more advanced technologies exist and also likely that these societies use means other than the electromagnetic spectrum for interstellar communication, it seems also likely that extraterrestrials would know that a society like us, with our primitive technology, would use that spectrum. The silence of the elders then implies that they do not wish to communicate with us primitives.

There could be many reasons for this, including our own long-televised evidence of violence and injustice to one another, or maybe just that the grown-ups know we need to prove ourselves to be much more civilized before we are allowed to learn of the advanced societies. Like most children, our potential is great, but until we have a better track record, it isn’t at all clear that our potential is for good.
Ed Berg, Salida, Colo.

Skin to neuron cells
The article “From skin cells to neurons, with no middle man” (SN: 2/27/10, p. 5) describes the transformation of “skin fibroblast cells from mice into working neurons by using viruses to insert genes that encode transcription factors.”
This is amazing.

I wonder if a similar process could be partially responsible for the spread of cancers through the body or for the growth of tumors — that is, cancer spreading and growing by transforming other cells and not just by metastasis and cell division. Cancer cells have a hyperactive metabolism and higher rates of cell division. Perhaps excess transcription factors (the proteins) for oncogenic genes could be absorbed by other cells after leaking out of a cancer cell. Or perhaps hyperactive oncogenic genes (the DNA) could be absorbed by other cells after an apoptotic (programmed cell death) explosion of a cancer cell.
Elizabeth Mansfield, North Potomac, Md.