Viewpoint: Yes, observations have raised the estimate of the Hubble constant from 50 to near 100 km/s/Mpc.

Viewpoint: No, the best observations regarding the age of objects in the universe require a Hubble constant significantly below 100 km/s/Mpc.

One of the most familiar of scientific phenomena is the Doppler shift of sound—the change in pitch of sound being emitted by an object moving toward or away from a listener. The pitch of a train whistle invariably appears to lower as the train passes the listener, and this change is caused by the compression and elongation of sound waves by the motion of the object. Longer-wavelength or, analogously, lower-frequency sound waves are perceived by the listener as having a lower pitch.

The same phenomenon applies to light...