Dark energy

[Martin]

 

Anyway' date=' if you are able to find more about the DE, keep me posted.

 

[/quote']

 

this isnt about DE

I was just at arxiv and saw a new paper "How Black Holes Get their Kicks"

http://arxiv.org/astro-ph/0408492

 

it is a SciFi image out of regular science. Two black holes approach each other and merge. the resulting black hole is suddenly traveling 300 km/second.

that is fast, the earth in orbit around sun goes only 30 km/second

human rockets boost just to a few km/second.

what gave the merged black hole that kick---what was the balancing momentum in the other direction like the jet of a rocket's exhaust?

 

maybe somewhere there is a blackhole coming in our direction at 300 km/second :smile:

--------------------

 

this IS about DE, I just found it today for some reason

http://arxiv.org/gr-qc/0307042

by Laurent Nottale, a French at the Paris-Meudon observatory.

he says something like what I was saying earlier. there is this

constant L----he says it is 9.3 billion lightyears----I was saying 9.5.

he says it could explain the Pioneer Anomaly

 

the main purpose of the new theorizing is to account for both Darks (DM and DE) but also there is a funny thing that happened with two spaceprobes when they got 50-70 AU from the sun ------50-70 times as far as the earth is. It has been on people's minds to explain it and Laurent Nottale includes this oddity of the behavior of Pioneer 10 and Pioneer 11 along with the other L stuff.

 

--------------------------------

still no popular sci journalism articles about this, probably wont be for a long time

----------------------------

 

Anyway, since the idea of a black hole suddenly being given a huge speed (enough to leave this galaxy) by a natural process is kind of interesting to imagine, here are the details of that paper. For more detail, download the PDF. this is just the summary.

------quote-----

How black holes get their kicks: Radiation recoil in binary black hole mergers

Scott A. Hughes (MIT), Marc Favata (Cornell), Daniel E. Holz (Chicago)

Contribution to Proceedings of the Conference on "Growing Black Holes" held in Garching, Germany, on June 21-25, 2004, edited by A. Merloni, S. Nayakshin and R. Sunyaev, Springer-Verlag series of "ESO Astrophysics Symposia"

 

Gravitational waves from the coalescence of binary black holes carry linear momentum, causing center of mass recoil. This ``radiation rocket'' has important implications for systems with escape speeds of order the recoil velocity. We describe new recoil calculations using high precision black hole perturbation theory to estimate the magnitude of the recoil for the slow ``inspiral'' coalescence phase; coupled with a cruder calculation for the final ``plunge'', we estimate the total recoil imparted to a merged black hole. We find that velocities of many tens to a few hundred km/sec can be achieved fairly easily. The recoil probably never exceeds about 500 km/sec.

----end quote---

[Thales]

I know what it is, but I'm not telling.

 

Well at least not yet, give us a few months

[Alexa]

Hi Martin,

 

I think you'll be interested by this :

 

A project called LISA (Laser Interferometer Space Antenna) would search for "gravitational waves" kicked up in the aftermath of black hole mergers, perhaps proving that such colossal collisions do occur. The NASA satellite is tentatively slated for launch in 2008.

 

A vastly improved understanding of dark matter is also needed. Several telescopes should contribute to this effort, but since no one knows what the stuff is, forecasting any sort of resolution is highly speculative.

 

I took this info from an article on space.com. If you are interested to read the article completly, let me know.

 

I'm pretty sure we'll find one day the entire explanation for DM and DE. One thing is sure : they exist and you can find them all into this Universe.

 

You know that even for discovering atoms, scientists needed a long time to determine what they are !

 

Alexa

[YT2095]

Why is it so mysterious? We don't know what it is!

 

I like that ))

[Martin]

 

...I think you'll be interested by this :

...

...

I took this info from an article on space.com. If you are interested to read the article completly' date=' let me know.

...[/quote']

 

Yes Alexa, if it is not a bother, I would like the link to that article.

It looks as if the article is making a survey of future research directions

and that's often interesting to check out.

 

thanks,

Martin

[Alexa]

Here you have it :

 

http://www.space.com/scienceastronomy/blackhole_history_030128-3.html

 

Alexa

[Martin]

thanks Alexa, hey people this is a pretty interesting article

I hadnt seen it.

it describes the "middleweight" BH problem which is a good problem.

we see solar size BH and we see massive ones like several million or even billion solar---these masses have been measured

but we dont see the in between stage

 

how do they grow so fast from solarmass scale to millions of solars?

how do they cross that gap so quickly that we dont see intermediates?

 

also there is the "spin" BH problem that this article talks about

if BH grew by holes merging with holes then the random spin axis of the two mergees would tend to cancel and kill spin

 

so one of the guys quoted says that the growth must be by sucking in a lot of gas, which spirals in and adds to the spin

because we see big holes having a lot of spin

 

this is smart, these clever humans are figuring out how the massive BH at centers of galaxies must have grown from initially small ones only a few solarmass.

 

 

and they say this: we see galaxies merging all the time and this is a good way to replenish the gas that one of these giant BH is growing on. the new galaxy that falls in brings lot of gas with it and this feeds the BH.

 

this is what this Alexa-article says. it is a good article

[Martin]

--------------------

 

this IS about DE' date=' I just found it today for some reason

http://arxiv.org/gr-qc/0307042

by Laurent Nottale, a French at the Paris-Meudon observatory.

he says something like what I was saying earlier. there is this

constant L----he says it is 9.3 billion lightyears----I was saying 9.5.

he says it could explain the Pioneer Anomaly

 

the main purpose of the new theorizing is to account for both Darks (DM and DE) but also there is a funny thing that happened with two spaceprobes when they got 50-70 AU from the sun ------50-70 times as far as the earth is. It has been on people's minds to explain it and Laurent Nottale includes this oddity of the behavior of Pioneer 10 and Pioneer 11 along with the other L stuff.

 

--------------------------------

[/quote']

 

OK please listen up gentlemen. Laurent, like some Cyrano de Bergerac figure, tosses 3 buns in the air and skewers them with his epee, one bun is DE, one bun is DM, and the third is the Pioneer anomaly.

 

actually this paper is the iceberg tip only, there are other people and other papers, but this is a sample of yet unpublicized work

 

the skewer or the epee is this length L = 9.3 billion lightyears.

 

1. to explain accelerated expansion and dark energy effects, he says simply that the observed einst. cosm. const curvature (often called lambda)

is given simply by

lambda = 1/L²

space is like prestressed concrete and comes with this built in small extra curvature. that takes care of that. (this is what determines the size of the length L, it is in effect observed)

 

2. dark matter effects are mostly the galaxy rotation curves, which require extra mass clumping in the galaxies if one uses the ancient Newtonian formula for gravity. the outer fringe of each galaxy is going too fast for Mr. Newton.

to explain this there is the MOND idea of modified newtonian dynamics.

and this requires a threshhold acceleration.

 

as luck would have it this threshhold acceleration quantity turns out to

be

a =c²/L

 

you take the same length L as in point 1. and you make the only acceleration quantity you can, up to constants, using that length and the speed of light and you get the right acceleration for MOND! OK, maybe space has this length L built into its workings, its bendings, its geometry, and this is something deep in the inner proportions of nature, like other fundamental physical constants have turned out to be. Maybe.

 

3. and now Laurent skewers the third bun.

it turns out that the observed extra acceleration in the Pioneer 10 and 11 after they got 30-70 AU out from the sun and Mr Newton was saying that they would almost be feeling nothing from the sun. it turns out that this unexpected acceleration that was observed, is also c²/L

 

cant finish this post have to go. back later

[Alexa]

I'm glad you like the article.

 

I'm trying to do a paste for the an universe chart, but it seems it doesn't work. Sorry, I'll try to find another solution, as I think it's worth it.

Universe.chart.doc