APOD: When Black Holes Collide (2015 Oct 20)

[RocketRon]

Dark matter makes up about 20% of the Universe. And it is something we observe- it is not invisible.
.

Space.com (a reasonably reliable source ?) puts dark matter as 80% of the MASS of the universe, and 'hypothetical'
http://www.space.com/20930-dark-matter.html
Dark energy, also hypothetical, makes up a considerable % of the energy...

"A third possibility exists — that the laws of gravity that have thus far successfully described the motion of objects
within the solar system require revision."

[RocketRon]

No, I don't! Please tell me what's wrong and why!

Nothing catastrophic I can spot. !

We are being fed a line here that physics and astrophysics and astronomy are all cut and dried and fine and dandy,
when nothing could be further from the truth. ?
As this article ably points out, in general terms.

Large levels of dark energy and dark matter are required to make the sums add up.
If these prove no more real than phlogiston, ....

[geckzilla]

Well, it's not as if people aren't trying very, very hard to modify gravity or find some other explanation for dark matter. MOND has failed repeatedly to explain things better than the lambda cold dark matter model. If you follow the (abundant!) evidence, it points to dark matter as being the most probable culprit. It's not just a filler or something pulled out of one's nether regions. I don't think you give it or the astronomers who study this stuff enough credit, Ron.

[Markus Schwarz]

Dark matter makes up about 20% of the Universe.

Space.com (a reasonably reliable source ?) puts dark matter as 80% of the MASS of the universe, and 'hypothetical'
http://www.space.com/20930-dark-matter.html
Dark energy, also hypothetical, makes up a considerable % of the energy...

To clarify the confusion (I hope): the energy density content of the universe is (roughly, give or take a few percent) 70% dark energy, 25% dark matter, and 5% "normal" matter. Thus, the 30% "matter" part consists of 83% dark matter and 17% "normal" matter.

[Chris Peterson]

Dark matter makes up about 20% of the Universe. And it is something we observe- it is not invisible.

Space.com (a reasonably reliable source ?) puts dark matter as 80% of the MASS of the universe, and 'hypothetical'
Dark energy, also hypothetical, makes up a considerable % of the energy...

Others have pointed out the error in your statement here. And FWIW, electrons and protons are "hypothetical" as well, given your usage.

"A third possibility exists — that the laws of gravity that have thus far successfully described the motion of objects
within the solar system require revision."

A possibility that very few consider likely as an explanation for dark matter. It may turn out that a revision of gravity becomes part of our understanding of dark energy.

[RocketRon]

Others have pointed out the error in your statement here.

The error in MY statement !!!
There is not a lot of difference betwixt 80% and 83%,
but 20% on the other hand.....

And FWIW, electrons and protons are "hypothetical" as well, given your usage.

Now we are starting to agree on something.
Although at least these can be 'observed', to some degree at least.
They have not been merely manufactured to fill some gaps in some mathematical conundrums.
Although precisely what they consist of is the matter of considerable discussion, the jury is still out...

As more than a few have pointed out, physics and astronomy became a matter of 'belief' (= a religion ?), quite a while back.
And may yet need some serious revisions, as observations and discoveries add to the picture.
Anyone who claims the theories are all solid and finished and its all over bar the shouting hasn't been paying attention....

[Chris Peterson]

Others have pointed out the error in your statement here.

The error in MY statement !!!
There is not a lot of difference betwixt 80% and 83%,
but 20% on the other hand...

If you still believe you statement wasn't in error, you need to review the explanation Markus gave you.

And FWIW, electrons and protons are "hypothetical" as well, given your usage.

Now we are starting to agree on something.
Although at least these can be 'observed', to some degree at least.

Both dark matter and dark energy are observed as well. The former, extensively.

They have not been merely manufactured to fill some gaps in some mathematical conundrums.

But that's precisely why they were "manufactured"!

Anyone who claims the theories are all solid and finished and its all over bar the shouting hasn't been paying attention....

I don't notice anybody making that claim. However, there are theories, such as GR, which are very unlikely to undergo any further major revision.

[Ann]

My own input here is of limited value, since my knowledge and understanding of math and physics is so limited. Nevertheless, to the best of my understanding, general relativity has passed every test that scientists have managed to throw at it. So clearly the foundations of general relativity are very sound.

The only problem with GR is that it is incompatible with quantum physics. That is indeed a very serious problem, and GR will have to be revised somehow to make it compatible with quantum physics and give us a (more) complete understanding of the universe.

In spite of that, however, GR has been incredibly successful.

Ann

[Beyond]

...GR has been incredibly successful.

Especially for dogs. But then dogs use a fuller version of GR. GRRRRRRRRRRRRRR

[geckzilla]

I think Ron's understanding may be in its infancy and he's projecting that onto everyone else... What do you say, Ron? Is it possible that you are the one in error, here? You should carefully consider your answer.

[Chris Peterson]

The only problem with GR is that it is incompatible with quantum physics.

Even that may be too strong a way of putting it. Our broad view of how the Universe works means that we really think GM and QM should both be tied together by a unifying law. Of course, it is possible this is wishful thinking, and they aren't connected. But most physicists believe they are, and that we'll find the unifying principles. Doing that, however, doesn't necessarily mean that GM will have to be modified. It may amount to nothing more than reframing it with some different math that gives the same results. That is, not changing GM, but finding a different way of looking at it in a QM context.

[ta152h0]

Black holes can't collide, they have the same flavor thereby repell each each other

[RocketRon]

I think Ron's understanding may be in its infancy and he's projecting that onto everyone else... What do you say, Ron? Is it possible that you are the one in error, here? You should carefully consider your answer.

I quoted Space.coms 80% for dark matter, and Marcus found 83%, as the mass in the universe.
I'd be curious where he found that number, it seems to be being revised upwards every time it is quoted.
?

As for science being a plethora of theories, paradigms and works in progress, we'd all agree with that - thats how science works, afterall.
We have come a long way since philostogen, everything revolving around the earth, and emotions coming from the heart.
Nothing is written in stone - except maybe down in the Geology Dept.

Back to my original question here - does anyone have the inside knowledge on this particular APODs search for 'gravitational radiation' ?
Is it still flavour of the month for how gravity actually operates - or are other theories sitting on the sidelines ??
Doubters are starting to get some press.....
http://news.discovery.com/space/astrono ... 150206.htm

[Chris Peterson]

I think Ron's understanding may be in its infancy and he's projecting that onto everyone else... What do you say, Ron? Is it possible that you are the one in error, here? You should carefully consider your answer.

I quoted Space.coms 80% for dark matter, and Marcus found 83%, as the mass in the universe.
I'd be curious where he found that number, it seems to be being revised upwards every time it is quoted.

No, you misunderstood what Space.com stated. Matter and energy are equivalent. So we understand the Universe in terms of its total energy content. That is divided up as about 68% dark energy, 27% dark matter, and 5% ordinary matter (mainly atoms). If you just consider the energy that is in matter form (dark matter and ordinary matter), 85% is dark matter and 15% is ordinary matter. But these two together still only represent 32% of the total energy in the Universe. You may see these numbers given plus or minus a small amount, depending on the source and the age of the source. But they're pretty close and aren't changing much.

Back to my original question here - does anyone have the inside knowledge on this particular APODs search for 'gravitational radiation' ?

What are you looking for? The frequency of gravitational waves produced when black holes collide is in the range that the LIGO instruments are designed to detect. We can expect such detections within the next two or three years. There are a few other instruments that are or will be looking for gravitational waves, but certainly LIGO is the likely detector for colliding black holes.

Is it still flavour of the month for how gravity actually operates - or are other theories sitting on the sidelines ??

Gravitation has been understood well for 100 years- including how it "actually operates". There are no viable theories (or really, even good hypotheses) outside of GR.

Doubters are starting to get some press.....
http://news.discovery.com/space/astrono ... 150206.htm

What you are listing here conveys no doubt about either GR or gravitational waves. It is about the signature that we'd expect to find on the cosmic microwave background from inflation. This article is about observations that might impact details of our cosmological model. Not gravity at all.

[geckzilla]

You need to learn to doubt yourself more, Ron. You'd learn a lot more if you realized you were wrong and went back and corrected your assumptions.

[RocketRon]

Wikis' take on dark matter is

Dark matter neither emits nor absorbs light or any other electromagnetic radiation at any significant level. According to the Planck mission team, and based on the standard model of cosmology, the total mass–energy of the known universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy.[2][3] Thus, dark matter is estimated to constitute 84.5% [note 1] of the total matter in the universe, while dark energy plus dark matter constitute 95.1% of the total mass–energy content of the universe.[4][5][6]

And much more.

Time will tell, as they say,
there is still much to find out....

[RockeRon]

Thankyou for your contribution geckzilla.
Any budding Einsteins will take great encouragement ....

Now demonstrate some knowledge, and analyze some of the alternative theories lurking in the wings ?
For there are many...
Even if they too have some large problems with some aspects.

Time will tell...

[Ann]

Thankyou for your contribution geckzilla.
Any budding Einsteins will take great encouragement ....

Now demonstrate some knowledge, and analyze some of the alternative theories lurking in the wings ?
For there are many...
Even if they too have some large problems with some aspects.

Time will tell...

Remember, Ron, that Einstein didn't become Einstein by sitting down and doubting existing theories, or by trying to convince those who believed in those theories that they were wrong. He became Einstein by coming up with his own ideas about the universe, and then he worked, and worked, and worked, to refine his own hypotheses. In the end he was confident enough to say that he knew he was right, and all tests of his theories have indeed proven him right, too.

So if you think you have a better idea of the universe than the Lambda Cold Dark Matter model (as I think it is called), keep on working on it! Maybe you can show it someone who knows math better than you do, and let that person try to develop your ideas. Einstein himself asked for help from mathematicians, so there is no shame in asking others to assist you.

But you should always remember that it is up to you to come up with a better idea than the one(s) you don't believe in. Expressing your dislike of existing ideas will really get you nowhere.

Ann

[geckzilla]

Thankyou for your contribution geckzilla.
Any budding Einsteins will take great encouragement ....

Now demonstrate some knowledge, and analyze some of the alternative theories lurking in the wings ?
For there are many...
Even if they too have some large problems with some aspects.

Time will tell...

I've done far more of this than you might guess. I already know there is no changing your mind since you show exactly zero ability to admit even the possibility of wrongness. It is almost certainly pointless to argue with you, but others reading this discussion/debunking may find it useful.

[BMAONE23]

What I found rather interesting were the stages that the smaller black hole went through in it's death spiral. At a couple points it seemed to temporarily split into two separate black holes. Trying to mind experiment this but I am falling short of the manifestation of a third gravity well.

As was indicated by a couple others here, I too think this is a lensing effect similar to the Einstein Lensing of light from behind the object. This being an Einstein lensing of the adjacent BH as both BH's were simulated to display the same effect

[Ron-Astro Pharmacist]

"In fact, at our best we are doing one part in 10,000 of a proton diameter."

https://www.quantamagazine.org/20151022 ... -gonzalez/

Puts splitting hairs to shame.

[Martin]

Thanks for the input guys but couldn't we expect the lensing effect be proportional?

[Markus Schwarz]

Thanks for the input guys but couldn't we expect the lensing effect be proportional?

Proportional to what? Also keep in mind that they are simulating the full Einstein equations in a non-linear regime, so my naive guess is to not expect a linear behaviour. I found this paper about the simulation and had a quick look at it. They discuss the multiple images due to the strong gravitational lensing.

[Martin]

Thanks Markus.

[neufer]

http://tinyurl.com/n9plqyg