LIGO reports new event

[swansont]

Two black holes, 14.2 and 7.5 solar masses. Final BH is 20.8 solar masses.

 

http://news.mit.edu/2016/second-time-ligo-detects-gravitational-waves-0615

 

https://www.newscientist.com/article/mg23030783-800-ligo-sees-new-gravitational-wave-from-more-doomed-black-holes/

[MigL]

We've used EM astronomy for hundreds of years ( if not thousands ).

We're just starting to use gravitational astronomy ( the only other long range effect ).

It will take time and effort, but eventually it'll provide as much, if not more, information about the universe we live in.

[geordief]

Sorry to harp on about this but is it equally correct to say that these gravitational waves are "alternately squeezing and stretching the space they pass through" as it is to say that they are "alternately squeezing and stretching the spacetime" they are passing through?

 

The former description is from the BBC website: http://www.bbc.com/news/science-environment-36540254

 

The first way is how I see it described in this story but I always feel that "space" is short for"spacetime" but am I wrong and is "space" indeed the correct description in this case?

[Strange]

Both space and time get stretched and squeezed, so space-time is more accurate.

[geordief]

If these waves are strong enough would they potentially break the bonds that hold the material they pass through together?

 

Or would the material itself notice nothing and the effect would only be measurable to an observer at a remove ?(I am guessing definitely the former -it is like a bomb passing through like an express train at the speed of c)

 

What size of a source would be required ,I wonder for a destructive force to be observed?

 

From the same article:

"Having an observatory in space would enable the detection of gravitational waves of different frequencies to those sensed on the ground, including the warping generated by mergers of truly gargantuan black holes - ones that are many millions, even billions, of times the mass of our Sun."

[Strange]

From all the comments I have read, even close to the black holes, the effects would be too small to even be noticeable, never mind destructive. For example:

 

How far away do you have to be from this kind of black hole merger to live to tell the tale?

Stuver: For the black hole binary we detected with gravitational waves, they produced a maximum change in the length of our 4 km (~2.5 mi) long arms [of] 1x10^-18 meters (that is 1/1000 the diameter of a proton). We also estimate that these black holes were 1.3 billion light-years away.

Now assume that we are 2 m (~6.5 ft) tall and floating outside the black holes at a distance equal to the Earth’s distance to the Sun. I estimate that you would feel alternately squished and stretched by about 165 nm (your height changes by more than this through the course of the day due to your vertebrae compressing while you are upright). This is more than survivable.

http://gizmodo.com/your-questions-about-gravitational-waves-answered-1758269933

[michel123456]

But the meter you use to measure your height would be squeezed by the same amount. So you would measure absolutely nothing.

[Strange]

But the meter you use to measure your height would be squeezed by the same amount. So you would measure absolutely nothing.

 

Correct.

[geordief]

But the meter you use to measure your height would be squeezed by the same amount. So you would measure absolutely nothing.

aha ! (actually I now see my question in post #5 was framed illogically-I gave 2 complimentary "alternatives" and plumped for the "former" as if it was the opposite of the "latter")

 

You have cleared it up for me ,though.

 

Can we say,then that the effect is "frame dependent" or does that go too far?

[Sensei]

But the meter you use to measure your height would be squeezed by the same amount. So you would measure absolutely nothing.

 

Distance is also measured by laser, photons send to object, reflected, and measuring time needed to return photons back.

[TakenItSeriously]

I've always suspected that spagettification near BHs was an observer dependant spacetime illusion, similar to length contraction at close to light speed.

 

The thinking is that the delta force between your head to feet would physically tear you apart.

 

As I see it, you dont feel a thrust when in free fall because it is spacetime that is accelerating towards the planet.

 

So you shouldnt feel the delta forces either because it is spacetime that is getting stretched not the body in free fall.

Edited June 22, 2016 by TakenItSeriously

[Strange]

I've always suspected that spagettification near BHs was an observer dependant spacetime illusion, similar to length contraction at close to light speed.

 

 

There are basically tidal forces. Yes, you are in free fall but one end is free falling "faster" than the other.