[thedoc (OP)]

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?

[jeffreyH]

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.

[evan_au]

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:

Why are we trying to detect gravitational waves?

Gravitational waves are an incredibly subtle effect, first proposed by Poincaré 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

[Bill S]

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 that’s the case, it’s 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. 

[yor_on]

Let me put it this way. It depends on preconceptions.

You think this life is as real as it can be, right?
You think the universe you perceive is the exact same as any others perception?

And then you read Einstein, and the people trying to interpret him.
You get a geometrical universe, or you get one limited by 'forces'.

Or you get mine

[yor_on]

Nobody's perfect, and the thread is old :)
Still, I would use one thing quantum dynamics stand for. Exploring what the f* a locality means.
Because I think that's the way
=

And I do hate that I every time have to tell TNS not to use those full-breaded
 'moons' for a smile

[Bill S]

You think this life is as real as it can be, right?

That depends, to a great extent, on a number of things.

1. What do you mean by "real"?
2. Do you mean "real" within our 3+1D  perception of the Universe?
3. Do you include some concept of reality that is outside our perceived Universe?
4. Obviously, perceptions of reality can, and do, differ; but are you thinking there may actually be variations in objective reality?

[Janus]

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.

No, Special Relativity is a sub-set of General Relativity.  You get SR if you apply GR to a region of flat space-time. It is "Special" because it only applies in the case of flat space-time where GR applies in all "General" cases.  We only really separate the two because SR is easier to work with when dealing with situations where the local curvature of space has minimal effect on the results. (For the same reason we still use Newtonian physics when sending probes out into the solar system even though Relativity would give an more accurate answer. The increased accuracy is not required to do what we want to do.)  They are not radically different theories.

[jeffreyH]

I had already reread that post of mine yesterday and had come to the same conclusion.

[yor_on]

'Reality' is what you perceive, and live in. It's the rules, principles, properties, and laws, that define your survival. It can also be purely subjective, but that shouldn't change any of the stuff I stated before. As for multi dimensional theories I'll leave that aside, until seeing it proved, in which case we need to include it.

Still, yeah. I do Bill. I'm starting to think that if what defines us are abstractions, then maybe other abstractions are just as 'real', as for example 'ethics'. In its turn leading to a universe of a slightly different 'entropy' than normally meant, well possibly :)
=

And that means 'choices', and presumes a 'free will' existing.
But looking at Quantum mechanics I would say that this already is 'baked in' into our 'universe'.
=

And in such a universe, what we don't do I expect to be just as important as what we do. It's about ethics. Whether that leads anywhere else I don't know, I don't consider it a 'religious insight' but it might be about our survival.

You might call it 'meta physics', but in that case anything getting out from the four 'dimensions' we exist in should be treated likewise.
=

As for wondering whether there are different 'realities' we just need to look to relativity to get an answer. What we call 'locality' relative a 'abstract 'whole' universe' including 'everything'. Locality is your reality, the 'universe' you perceive is yours, not mine. The 'whole universe' in where we all have a share is actually an abstraction too. You should take it with a pinch of salt though, and you can see it two ways, either locality is all or abstractions are all. Or none of it, maybe there is still something new waiting for us. 

If you for example look at string theory you will find  'one dimensional strings' as a 'origin' of this universe, alternatively you can check on Smolin's strings and loops. Most of the ideas I've seen builds on this universe being a result of something else, something that allow the 'universe' to exist by ? chance ? Because it is coexisting with us, whatever it is. Possibly time is a result of this universe existing, looking at Einstein I read him that way, that's one reason why I like to think of 'it' as a 'fault' in something else. We're inside 'it' and we can't look out, so the 'reality' we all face is 'time'. Dying is no illusion.

So yeah, 'reality' is a strange word but locally it exist.

[Paul25]

It makes me wonder too