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Author Topic: If gravity can bend light could stars be closer than we thought?  (Read 231 times)

Offline thedoc

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william roberts asked the Naked Scientists:
   If gravity can bend light, maybe distant stars aren't so distant after all  - I mean, the light could have been bent all over the place by the time it gets to us.

PS  I was surprised none of you mentioned Spirulina in the 'single food' debate as it is very widely used in elimination diets since it has no known allergens and has every single nutrient in correct proportions.
What do you think?
« Last Edit: 26/09/2016 14:23:02 by _system »


 

Offline evan_au

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Quote from: william roberts
the light could have been bent all over the place by the time it gets to us.
This is a known effect called "gravitational lensing", and it is observed with:
- distant galaxies that have their light bent into bizarre shapes by nearer galaxies. The shape of this distortion is used to infer the distribution of unseen "dark matter" around nearer galaxies and galaxy clusters
- planets or dim stars passing in front of more distant stars causes a temporary change in brightness of the distant star (microlensing)

There have been extensive searches for microlensing events, especially in the early days of Dark Matter searches, when it was thought that large objects like black holes, cold burnt-out stars or planets wandering between the stars could account for the "missing matter". So there is a reasonable understanding of the incidence of gravitational lensing, and it is not very frequent.

The Kepler spacecraft examined the brightness of many stars over several years. However, it's analysis software was searching for periodic planetary transits, rather than 1-off gravitational lensing events.

The Gaia spacecraft is measuring the positions and motions of a billion stars in our part of the galaxy (listen to TNS podcast from around 20th September 2016). Because Gaia measures the position of each star many times over 5 years, the effect of a transient gravitational lensing event should not affect the results.

https://en.wikipedia.org/wiki/Gravitational_lens
https://en.wikipedia.org/wiki/Gravitational_microlensing
 

Offline PmbPhy

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william roberts asked the Naked Scientists:
   If gravity can bend light, maybe distant stars aren't so distant after all ..
Light is only bent when it passes by a gravitational object like a star. Otherwise we can see the light with no bending at all. E.g. the first observation of gravitational deflection of light was  done during an eclipse of the Sun. The position of a star near the Sun's edge was measured. It was then compared to the position of the star when the light wasn't passing by the Sun and it was determined that the Sun caused the light to be deflected as it passed by it. Measurements of the distance to any star is never influenced by the Sun's gravitational field. In fact stars are usually observed at night in which case the light arrives at the Earth never passing the Sun on its way.

Do the answer to your question is No.

Suggestion: In the future you should keep in mind that astronomers and astrophysicists know precisely what they're doing and as a group they'd never make such a terrible mistake.
 

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