Successful detection of gravity waves!

[freyar]

Was just wondering: What is the eventual fate of the energy emitted as gravitational radiation by an event like this? Does it mostly radiate into the background, never to interact with matter, always to remain as a ripple in spacetime?

As the wave passes through matter, it will give a bit of that energy to the matter, but it won't lose more than a small fraction of its energy. So it will just continue spreading out from the initial event, with the energy getting less and less dense as it spreads out. (It's worth mentioning that there are some subtleties involved in defining what you mean by the "energy" of a ripple in spacetime, but it's fairly clear when the ripple is very small like what LIGO measured. Right when it left the black hole merger was potentially more difficult.)

If most matter eventually goes through this sort of process, what percentage of energy will eventually be converted to gravity waves? This one event had about a 5% conversion rate. If we look at one of the big (billion solar mass+) black holes at the centers of galaxies, depending on the sequence of mergers which happened, a big percentage of the mass energy of the black hole might have been radiated away.

Though, the milky way galaxy is estimated at about 10^12 solar masses (1 trillion), so that's a small percentage of the milky way mass lost.

Wow, the ultimate fate of everything in the universe? Big question! But people have thought about this to some extent. It's possible that the universe's expansion could eventually stop and reverse, leading to a "Big Crunch." Given that we know the expansion is accelerating, it's more likely that it expands forever. In that case, yes, any mass that isn't converted into radiation will eventually end up in rather large black holes (this is extremely long after the stars all burn out). And eventually, there'd just be one large black hole in any region that could be seen. Now if we wonder how much of the mass might be converted to gravitational waves during this agglomeration process, it probably is a few percent of the mass that gets converted to gravitational radiation at most. I haven't done the math, but I'd think that a smaller percentage of mass gets converted to gravitational waves if a smaller object falls into a really big black hole.

 

[Scott DeWar]

Hi, the electrician here . . . . .

I was wondering if these ripples would interact in some way with neutrinos, anti matter or photons?

 

[Morrus]

Hi, the electrician here . . . . .

I was wondering if these ripples would interact in some way with neutrinos, anti matter or photons?

I know nothing about neutrinos, but antimatter and light (photons) are both affected normally by gravity.

 

[tomBitonti]

I was looking more into the amount of energy that is present in the universe as gravity waves, and found this:

http://www.tapir.caltech.edu/~teviet/Waves/index.html

In particular:

http://www.tapir.caltech.edu/~teviet/Waves/gwave_spectrum.html

Relic background: A stochastic signal from the Big Bang itself, this consists of quantum fluctuations in the initial explosion that have been amplified by the early expansion of the Universe. While the spectral shape of this source can be predicted, its overall strength is highly uncertain, but is constrained by the fact that gravitational wave perturbations are one of several components contributing to the observed temperature fluctuations in the cosmic microwave background. This limits the maximum strength of gravitational waves at cosmological length scales. Two curves are shown: one at the upper limit of the observational constraints, and another an order of magnitude weaker.

Also:

In particular, the length scale of a "typical" black hole 10× as
massive as our Sun is 14km, and such objects achive speeds around c
only when they collide, which might occur on a yearly basis within a
volume of radius 6×1020km (20 megaparsecs). So the strongest waves we
expect to observe passing the Earth will have h ~ 10-20 or less. This is
enough to distort the shape of the Earth by 10-13 metres, or about 1%
of the size of an atom. By contrast, the (nonradiative) tidal field of
the Moon raises a tidal bulge of about 1 metre on the Earth's oceans.

Thx!
TomB

 

[Scott DeWar]

Thank you. that puts things into perspective.

 

[trappedslider]

 

[Scott DeWar]

yeah, I saw that XKCD the other day and laughed then too

 

[Dannyalcatraz]

I confess I had to think about it a minute.

 

[Umbran]

I was wondering if these ripples would interact in some way with neutrinos, anti matter or photons?

In the sense that *everything* interacts with gravity, yes.

You can think of it less as "these ripples interact with..." so much as "these ripples change the shape of the universe that these things move in".

As for how much energy there is in gravitational waves floating around out there - there's a sort of upper bound. We have detectors. They do see some noise, but not huge amounts. We can see an (admittedly powerful) event from a billion light years away. That means there's not all that much "static" out there. Variations in distances we from such waves are *tiny*. Like, fractions of the diameter of a proton, kind of tiny.

We are not tossed on a stormy gravitational sea. We are in gravitational doldrums, glassy flat.

 

[Scott DeWar]

so the"waves are of a heaving sigh. I figured as such or we would be tossed about like a sip in a storm with no rudder or sails.

about my question I mad, I asked it backwards.

let me put it this way: I moved to Missouri when I was 12. There was a pond about 100 yards away we went fishing and swimming in. During the dog days of summer - no wind at this time - the pond surface was glassy smooth. Now there was an old dead tree in the near center of this pond and we would row out to it and fish there.

Now that I have given you a picture, Here is my point. I remember throwing rocks in the pond and watching the ripples. The tree, a steadfast object, cause a disturbance. from what I watched it was like using echo location as the ripples bounced off the pond's edge and the tree. Are the objects or particles that the gravity waves do not affect that would bounce off of to give their presence away alike echo location?

Sorry about the other question, I pretty much knew the answer to that.

Scott "the overly curious" DeWar
AKA in RL As David A Johannes