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Author Topic: If gravity is a warping of time, why are we trying to detect gravity?  (Read 337 times)

Offline thedoc

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David asked the Naked Scientists:
   If, according to Einstein, the perception of gravity is based on the warping of time, my question is:-

Why are we trying to detect gravity?
What do you think?
« Last Edit: 28/09/2016 14:48:46 by jeffreyH »


 

Offline jeffreyH

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David asked the Naked Scientists:
   If, according to Einstein, the perception of gravity is based on the warping of time, my question is:-

Why are we trying to detect gravity?
What do you think?


Time dilation is an effect for which we are trying to find the causes. Note I said causes plural. We have both special and general relativity as the causes for this phenomenon. These are two radically differing theories. Ultimately the search is for the mechanism behind the effects. Namely the mechanism of universal gravitation.
 

Offline evan_au

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Quote from: David
Why are we trying to detect gravity?
Gravity is very important to humans, as has been known since prehistory
- A descent under Earth's gravity for just a few seconds is likely to prove fatal if you land on a hard surface. This was used to hunt herds of animals.
- Astronauts spending just 6 months in space suffer severe loss in bone density and muscle mass, despite exercising very vigorously to minimize the effect.
- Falls are a major cause of disability and death in the aged, and a major cause of injury and lost time in the workplace

The importance of gravity was known well before humans had developed clocks accurate enough to detect time dilation effects.
But it is important to understand the effects that gravity has on time, because that explains the spectra of white dwarf stars, and enables your GPS receiver to work accurately.

Perhaps the question you meant to ask is:
Quote
Why are we trying to detect gravitational waves?
Gravitational waves are an incredibly subtle effect, first proposed by Poincarť in 1905, and later supported by the mathematics of Einstein's General Theory of Relativity (although even Einstein was unsure over the succeeding 20 years or so whether they were real or an artifact). It has taken over a century to develop technology capable of detecting them.

The detection of gravitational waves announced early in 2016 was an achievement in several respects:
- It was (yet another) proof of the amazing accuracy of Einsteins general theory of relativity
- It was the most direct evidence to date of the existence of black holes (astronomers are sure they exist, and have many candidates, but they just can't see the black hole itself!)
- It surprised astronomers with the size of the black holes (about 30 times the mass of the Sun)
- But probably most importantly, it provides a pointer to a totally new way to look at the universe, able to peer through dust and distance to detect the most violent events in the universe (soon we will have detectors in multiple countries - and perhaps, in space).

See: https://en.wikipedia.org/wiki/Gravitational_wave
 

Offline Bill S

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Hi David; great as are the responses so far, I wonder if they answer your question.  Were you asking why, if gravity is the curvature of spacetime, are we still investigating it as if it were a mysterious force?

If thatís the case, itís probably important to remember that, in spite of the fact that some experts insist that gravity is not a force, this statement is misleading.  Pete will be able to tell you more about this than I can, but it may be wise to think of gravity as a force that is better described by the mathematics of spacetime curvature than by Newtonian mechanics. 
 

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