Available online
Description
To Newton it was only an isolated fact that the effects of gravity could be mimicked in an accelerating frame, but to Einstein this principle of equivalence was the clue to a new theory of space, t...ime and gravity. This programme is set in the future. In a deep space probe, operated by robots, we see the success and the limitations of the principle of equivalence.
To Newton it was only an isolated fact that the effects of gravity could be mimicked in an accelerating frame, but to Einstein this principle of equivalence was the clue to a new theory of space, t...ime and gravity. This programme is set in the future. In a deep space probe, operated by robots, we see the success and the limitations of the principle of equivalence.
| Module code and title: | S354, Understanding space and time |
|---|---|
| Item code: | S354; 10 |
| First transmission date: | 18-07-1979 |
| Published: | 1979 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:19:05 |
| + Show more... | |
| Producer: | James Burge |
| Contributors: | Paul Clark; John Westbrook |
| Publisher: | BBC Open University |
| Keyword(s): | Accelerating frame; Einstein; Equivalence principles; Gravity; Light bending; Newton; Robots; Shuttle |
| Footage description: | NASA film of the space shuttle being tested. Animations show the space shuttle in orbit launching a deep space probe. Commentary by Alan Cooper introduces the programme. Shots of two-robots inside the simulated deep space probe. They mistake the acceleration of the probe for the presence of a gravitational field. Paul Clark, acting as mission controller explains the background to the principle of equivalence. The robots on the probe report a frequency shift of a laser beam in a frame under acceleration. Paul Clark points out that according to the principle of equivalence, such a frequency shift should also take place under the influence of gravity. Alan Cooper, at the Jefferson Physical Laboratory, Harvard University, looks over and explains the experimental apparatus which tested, for the first time, the frequency shift in gamma rays due to the earth's gravity. Cooper goes on to describe another experiment done using hydrogen masers and a satellite which measured frequency shift of radio signals due to the effect of gravity with even greater precision than the above experiment. Shots of a hydrogen maser as he talks. The robots inside the space probe report the bending of a laser beam under the influence of acceleration. Paul Clark discusses briefly an experiment which confirmed Einstein's prediction that light is also bent in a gravitational field. Paul Clark and the robots discuss how the effects of a real, non-uniform gravitational field differ from the effects of uniform acceleration. They however, that if both the spatial extent of the observing volume and the time of the observation are sufficiently limited, then the principle of equivalence holds. Paul Clark sums up. |
| Master spool number: | DOU2843 |
| Production number: | FOUS071H |
| Videofinder number: | 2041 |
| Available to public: | no |
