Gravitational waves claimed to be detected by aLigo

You're implying that gravity is linked to 'time-travel'.. not me !
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Yes you are, you're just not aware of it ;)

Gravity obviously travels in a different 'medium' to light's duality (electromagnetic or photons), as with light vs sound
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Let me guess... the Eather?
 
Einstein was a smart dude.

The PhDComic describing gravity waves was pretty helpful.

What I'd like to know (and I guess what a lot of other people want to know): what exactly is space-time? The recent development of amplituhedra in simple cosmological models suggests that space and time are not fundamental, that they are artifacts of some more fundamental coordinates.
 
Among all those things that are on newspapers in this days about space time etc I read that for example planets are in orbit just because of the space perturbation that the sun makes, and that otherwise they will be travelling in a linear direction.

So I lost a bit of a point: gravity is an actual force, or is just the result of the space curved?

let's think of the same old trampoline, which curves if you put a big mass like the sun in it in the center. If you put another mass it will fall towards the sun but that happens not strictly because there is a force that is pulling the planet towards the sun, but because the trampoline is curved. I know that gravity is acting on the trampoline, but that is needed because the examples is just 2d, if you could modify not the trampoline but the 3d space then gravity it's not needed to make an object to fall towards the center.

So I am puzzled: is gravity a real force then or is just the effect of space change in shape due to mass (it seems the same but it's not).
 
Thunder Chicken said:
what exactly is space-time?
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Essentially it is just a mathematical concept to describe a common observation in multiple different phenomena. We have no idea if spacetime really exists in nature, since we cannot really touch it, but what we observe is right now well described by it. Especially the time-like component in space-time is pretty tough to describe. It is not the dimension of time, but rather a dimension that influences how time passes.

---------- Post added at 05:59 PM ---------- Previous post was at 05:58 PM ----------
fred18 said:
So I lost a bit of a point: gravity is an actual force, or is just the result of the space curved?
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Both at the same time. That is the joy of relativity.
 
fred18 said:
So I am puzzled: is gravity a real force then or is just the effect of space change in shape due to mass (it seems the same but it's not).
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It's due to the warping of spacetime by a mass.

This video helps a lot:

 
Thunder Chicken said:
It's due to the warping of spacetime by a mass.

This video helps a lot:
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Thanks, that was already pretty clear to me.

What I meant was: Newton's universal law of gravitation is then just a mathematical solution which describes how space is curved around the mass and how the curvature will influence it's velocity.

The difference to me is like the centrifugal force: it's not a true force, is due to the system that is turning, but we can feel it and calculate it precisely. Here again it's not due to physical interaction but to the fact that the system has a curved space.

That is against a bit my classical thinking of gravity as a real force which was different from centrifugal which is an apparent force. But also opens my mind a bit more on this and its implications.
 
fred18 said:
Thanks, that was already pretty clear to me.

What I meant was: Newton's universal law of gravitation is then just a mathematical solution which describes how space is curved around the mass and how the curvature will influence it's velocity.

The difference to me is like the centrifugal force: it's not a true force, is due to the system that is turning, but we can feel it and calculate it precisely. Here again it's not due to physical interaction but to the fact that the system has a curved space.

That is against a bit my classical thinking of gravity as a real force which was different from centrifugal which is an apparent force. But also opens my mind a bit more on this and its implications.
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There are no true or false forces. Only forces. And forces are all not real in that sense. They are just a way to describe how momentum is changed - the question is always: momentum of what in relation to what else? Why the momentum changes, is another topic. Is magnetism changing the momentum of a piece of iron directly? Or is it because the electromagnetic field is interacting with the iron and the magnet?

EDIT: Or maybe much better - everything I say, forces, momentum, mass ... all that jazz is essentially just a mathematical model to describe things that have no better name yet. Its only slightly more true than the user manual for your TV set - if it say that this button reduces the volume of the TV, it should be that way. Its easy to believe that Newton is talking about real things, because Newtonian physics work so great in our everyday applications - but in reality, they are just another approximation to some aspect of the universe. In Einsteins world, it all looks already different, despite still sharing common terms with Newton. And another new theory will likely still talk about forces, but again describe something slightly different.
 
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You guys are not thinking straight, and are caught up in terms of light speed limits, just like Newtonian sheeple before Einstein arrived ;)

Gravity is the new 'medium' which is not really understood at this moment, besides it's effects. :thumbup:
 
Col_Klonk said:
You guys are not thinking straight, and are caught up in terms of light speed limits, just like Newtonian sheeple before Einstein arrived ;)

Gravity is the new 'medium' which is not really understood at this moment, besides it's effects. :thumbup:
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Hear hear.... and you are going to tell us?
 
Oh, my appologies. I didn't realise I was feeding a troll. Won't happen again.
 
Urwumpe said:
Hear hear.... and you are going to tell us?
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:tiphat:
Of course...
:cheers:

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Most folks are missing the point..

For eons Newton theories were 'god'... and every researcher followed 'suite', proving that newton was the god.
Then Einstein shook the apple tree... I mean really.. a lot of people were pis..d off. But anyway it was a revelation.. until somebody dared to challenge Einsteins theories, and proved mathematically that they were correct. OK Einstein let a number or two slip by.

Stephen Hawking came up with a good idea.. Big Bangs and Singularities (IIRC). I never believed it for one second purely because it's a stupid idea.
Even string theory is pushing the limits
But you can twist things and prove it mathematically, no matter how bent it is - You can see where this is going.
But ultimately... does it look/sound sensible.. can it be simplified!
Yet most researchers pinned their research on the Big Bang/ect....why...
Simply $$$.. that's why :).. been there!! ;)

Gravity detection laser interferometers have been around for a long time.
Only now they discover gravity waves...
Really!!.. such a revelation, when it's visible all around.. if you can only see.
:rofl:
 
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I wonder how many researchers just saw their pet cosmological models disappear in a puff of smoke.
 
Thunder Chicken said:
I wonder how many researchers just saw their pet cosmological models disappear in a puff of smoke.
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:lol::lol:
I peeved off a lot in the geological research dept. when I mentioned how radiactive dating could be reset if the temperature was high enough..
They avoided me like the plague... but hey.. common sense please :thumbup:

I guess in all their years of academia they never thought about that ..:hailprobe:
 
Col_Klonk said:
:lol::lol:
I peeved off a lot in the geological research dept. when I mentioned how radiactive dating could be reset if the temperature was high enough..
They avoided me like the plague... but hey.. common sense please :thumbup:
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:rofl::rofl::rofl:

I might turn blue today.
 
Wow...that wavy data indicates that to 30 Sol mass black holes orbiting each other with a period of something like 0.05 s.

I think we need to get the CGI folks from Interstellar to animate this.
 
This is a really good site, the Simulating EXtreme Spacetime SXS collaboration:

http://www.black-holes.org/

http://www.youtube.com/c/SXSCollaboration

[ame="http://www.youtube.com/watch?v=-Kgfxl1Jk6k"]Merging black holes: Side view - YouTube[/ame]

---------- Post added 02-13-16 at 05:53 PM ---------- Previous post was 02-12-16 at 09:45 PM ----------

FYI The SXS Collaboration (I believe) are the same folks that consulted on the Interstellar black hole, so my wish was granted.
 
Surprisingly unremarkable.

Until you realize that at the end, the whole Universe literally shakes.
 
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