On 12 November Rosetta finished a 10 year, 6.4 million km journey and, hurtling through space at 55,000 kph, delivered a landing craft to the surface of a comet. Big numbers. But relevant? To answer that we need to delve into the world of relativity. But don’t worry, we’re only talking about the basic principles of relativity introduced by Galileo (1564-1642) and which laid the foundations for the works of Newton (1642-1726) and Einstein (1879-1955).
“any two observers moving at constant speed and direction with respect to one another will obtain the same results for all mechanical experiments”
Well, that sounds complicated, but what it boils down to it this – Individual objects might have attributes such as mass, colour and shape that permanently belong to that object. But this is not the case with speed. Speed is always relative to an observer.
Consider a train travelling along a track at 60 mph. And consider a passenger walking forward along the corridor at 3 mph. How fast is the passenger going? Well, relative to an observer standing to the side of the tracks he is travelling at 63 mph, but to a fellow passenger observing he is travelling at 3 mph. If the observer were in a car on a road parallel to the track, and travelling at 63 mph, the train passenger would appear stationary. A man on the moon would observe the passenger travelling at something like 1,000 mph, as the rotation of the earth would need to be taken into account, And from further away the observer would also notice the movement of the earth about the Sun.
So what of the Rosetta and that comet? Perhaps the comet was travelling at 55,000 kph relative to the earth. But was the movement of the earth, which Rosetta had not seen for over ten years, important? Perhaps it alluded to the difficulties overcome by the scientist who had to get the spacecraft to match the movement of the comet, but having done that the only speed relevant is that of the comet as observed from the space ship (or vice versa), which as it turns out, was a less-headline-grabbing 2.2 mph. Even at this low speed the lander bounced a couple of times before coming to rest two hours later.
So what do you think? Is it right to introduce words such as, “hurtle”, in order to attract people to the story, or is this unacceptable dumbing down?