Echos from *before* the Big-Bang

[ngcles]

Hi All,

Interesting article on the ABC website by Stuart Gary (of Starstuff).

http://www.abc.net.au/news/stories/2...section=justin


Best,

Les D

[CraigS]

Thanks Les;

This seems like another good follow-up article to Rolf's post the other day.

Cheers

[multiweb (Marc)]

Did I hear a big badaboom?

[Robh (Rob)]

Les, fascinating stuff.

Some more edible reading here ...
http://physicsworld.com/cws/article/news/44388

So much for the claimed random uniformity of the CMBR. Now we have the possibility of concentric circles. Is this the end of inflation theory?
I can buy that eventually black holes will eat up all the matter in the Universe. But can someone explain how black holes evaporate.

Regards, Rob

[CraigS]

Originally Posted by Robh

So much for the claimed random uniformity of the CMBR. Now we have the possibility of concentric circles. Is this the end of inflation theory?
I can buy that eventually black holes will eat up all the matter in the Universe. But can someone explain how black holes evaporate.

Regards, Rob

Hawking Radiation.

Cheers

[Robh (Rob)]

Originally Posted by CraigS

Hawking Radiation.

Cheers

Craig, thanks for that. Most succinct reply ever!
I didn't realise that Hawking radiation could lead to total evaporation of the black hole.

Regards, Rob

[CraigS]

Originally Posted by Robh

Craig, thanks for that. Most succinct reply ever!
I didn't realise the radiation could lead to total evaporation of the black hole.

Regards, Rob

No worries, Rob.

Even more interesting is the Black hole information paradox.

This issue has been going on for a long while. The solutions to the paradox is very interesting. It shows just how debatable the whole subject really is.

Cheers

[Robh (Rob)]

To begin, let me say I'm no expert on Big Bang cosmology.

From what I've read about black holes their temperature increases exponentially as they radiate away mass. The black holes then likely dissolve in situ in a burst of gamma rays. If the Universe is expanding, by what mechanism are these black holes going to collide to form the ripple of another Big Bang?
It seems to me a bit of a jump to say that the circles in the CMBR allow us to see through the Big Bang. Is it likely that an earlier signature will still be observable following another Big Bang? How will the ages of the concentric signatures match the age of distant objects embedded in the CMBR?
Is it possible for the concentric circles to indicate a Big Bang that occurred in stages with multiple inflation events?

Regards, Rob

[CraigS]

Rob;

I'm going to think of this one fairly lightly. It reminds me a bit of tea-leaf reading of patterns in the bottom of a teacup. (Or is that crop-circles?). I get the same feeling when I read about the 'holes' in the CMBR, which they say may represent where matter condensed to form galaxy structures. (And yes … this is an opinion ).

They have speculated about the possibility of multiple Bangs. The real news for me, is that they found a six-sigma level of significance that a concentric circle pattern exists in WMAP (7 year) and BOOMERanG98 data, thus eliminating the possibility of an instrumental cause for the effects.

I guess they wouldn't have found that, if they hadn't speculated in the first place.

So the door is now open for the story-tellers to come up with stories as to how these patterns may have gotten there. (Did I hear some say Erik Von Daniken ?)

Originally Posted by Robh

To begin, let me say I'm no expert on Big Bang cosmology.

From what I've read about black holes their temperature increases exponentially as they radiate away mass. The black holes then likely dissolve in situ in a burst of gamma rays. If the Universe is expanding, by what mechanism are these black holes going to collide to form the ripple of another Big Bang?

Theory allows for this to happen today .. black holes collide to form super massive black holes .. galaxies collide, etc.
The metric expansion of space however, is observed on a different scale. Where galaxies are moving apart with the expansion of space, fair enough .. I get ya .. its not likely that these (& their enclosed SMBHs) would collide.
I don't see this as a problem for their story, however.

Originally Posted by Robh

It seems to me a bit of a jump to say that the circles in the CMBR allow us to see through the Big Bang. Is it likely that an earlier signature will still be observable following another Big Bang? How will the ages of the concentric signatures match the age of distant objects embedded in the CMBR?
Is it possible for the concentric circles to indicate a Big Bang that occurred in stages with multiple inflation events?

Most of this is explained in the first three pages of the Penrose et al paper. This is the speculative part of what they're reporting and it seems like a fairly thin analysis to me (another opinion !! )

Cheers

[sjastro]

Hawking radiation as a blackbody radiation is the only radiation emitted by a black hole.

Other forms of radiation such as X-rays are not emitted by black holes, but rather by the heating of matter to extremely high temperatures before it passes through the event thorizon.

Regards

Steven

[CraigS]

Ahhh .. there's a magic term .. 'blackbody'.

Interestingly, I've read that the Sun is a 'blackbody' … it radiates light, but it reflects none. As I understand it, this formally defines it to be a 'blackbody' !!

Also, black holes have a temperature. Presumably, they thus also radiate heat.

Is it the Hawking Radiation only which carries this heat ? (Separate from the accreting matter, that is)

Cheers

[sjastro]

Originally Posted by CraigS

Ahhh .. there's a magic term .. 'blackbody'.

Interestingly, I've read that the Sun is a 'blackbody' … it radiates light, but it reflects none. As I understand it, this formally defines it to be a 'blackbody' !!

Also, black holes have a temperature. Presumably, they thus also radiate heat.

Is it the Hawking Radiation only which carries this heat ? (Separate from the accreting matter, that is)

Cheers

A blackbody is defined as being able to absorb light of all frequencies and emit heat.
I don't think the Sun would qualify as a blackbody under this criteria.

A BH can only generate heat through Hawking radiation.
The heat output is sensational. For a solar mass BH you will raise the temperature by one ten millionth of a degree above absolute zero. For larger BHs the increase in temperature is even less as a smaller percentage of mass is converted to Hawking radiation.

The temperature from matter falling into a BH is a very different picture. The temperature can be raised by hundreds of millions of degress.

Regards

Steven

[CraigS]

Originally Posted by sjastro

A BH can only generate heat through Hawking radiation.
The heat output is sensational. For a solar mass BH you will raise the temperature by one ten millionth of a degree above absolute zero. For larger BHs the increase in temperature is even less as a smaller percentage of mass is converted to Hawking radiation.

The temperature from matter falling into a BH is a very different picture. The temperature can be raised by hundreds of millions of degrees.

So the temperature is inversely proportional to the mass, eh ? (Apart from the temperature of the falling matter, that is .. they must consider this to be a separate item of the overall temperature of the whole thing (??))

Really interesting (to me), is that as a BH emits Hawking Radiation, the mass drops, and hence the temperature increases and, as it approaches Planck mass, the temperature is about the same as the Big Bang 10∧32 degrees !! (I think we've spoken of this in the past).

Clearly, they've been thinking about the relationships between the origin of the BB, and the possible role BHs may have played in it, for a while.

Penrose seems to see BHs playing major roles in multiple ways, though.

Interesting.

Cheers

[Robh (Rob)]

I was reading this article form 6 years ago ...
http://imagine.gsfc.nasa.gov/docs/fe...s/14may04.html

Of particular note are the last two paragraphs.

Also, more recently ...
http://www.technologyreview.com/blog/arxiv/24956/

Frampton talks of two inflationary periods.

Regards, Rob

[CraigS]

Originally Posted by Robh

I was reading this article form 6 years ago ...
http://imagine.gsfc.nasa.gov/docs/fe...s/14may04.html

Of particular note are the last two paragraphs.

Hmm … I would think this to be a leading contender for the Hot Dark Matter (HDM) candidate. The smaller the hole gets, (due to evaporation), the hotter it gets, hence I think this would be considered an HDM theory.
The HDM idea is still in contention, I think although Cold Dark Matter seems to still be favoured.
CDM has problems still though … the cuspy halo and missing satellites problems … swings of the pendulum it seems !

Originally Posted by Robh

Also, more recently ...
http://www.technologyreview.com/blog/arxiv/24956/

Frampton talks of two inflationary periods.

Regards, Rob

Hmm interesting again.
Thats a pretty big range !! …

So the conclusion is that dark matter is made up of black holes with a mass of between 10^6 and 10^-8 solar masses.

also ..

However Frampton's ideas can be better tested by looking for evidence of these primordial black holes, which should cause microlensing events: ie their gravity should focus the light from stars behind them as seen from Earth.

There's been quite a lot of development in the microlensing research field, this year I believe. We should keep an eye out for more words on this in the future.

Interesting stuff !

Perhaps we just live inside a black hole .. that make us all holograms, eh ?


Cheers

[CraigS]

Just released yesterday …

About a month after the initial paper, three groups rebut the Gurzadyan/Penrose cyclic universe theory:

No evidence of time before Big Bang, published 10th Dec 2010.

All three groups reproduced Gurzadyan's analysis of the WMAP data and all agree that the data do contain low-variance circles. Where they part company with the earlier work is in the significance that they attribute to these circles.
..
"The result obtained by Gurzadyan and Penrose does not in any way provide evidence for Penrose's cyclical model of the Universe over standard inflation," says Zibin.
..
Gurzadyan dismisses the critical analyses as "absolutely trivial", arguing that there is bound to be agreement between the standard cosmological model and the WMAP data "at some confidence level" but that a different model, such as Penrose's, might fit the data "even better" " — a point he makes in a response to the three critical papers also posted on arXiv. However, he is not prepared to state that the circles constitute evidence of Penrose's model. "We have found some signatures that carry properties predicted by the model," he says.

Interesting to see another model from a distinguished scientist (Penrose), going up against the mainstream one.

Just goes to show that the Scientific process does allow for consideration of competing theories.

Cheers

[mjc (Mark)]

Originally Posted by CraigS

Just goes to show that the Scientific process does allow for consideration of competing theories.
Cheers

Or maybe the power of the internet is challenging old ways of doing things. ArXiv doesn't present the same hurdles as the traditional paper journals and thus scientists have greater liberty of what they publish.

I think the rationale was intended as a quicker way of getting ideas circulated (as preprints) before going to conventional journals but appears to have evolved into an effective mechanism to publish without the intention of attempting to get past the restrictions of the traditional journals.

Old model slow - difficult to introduce new ideas - bias can exist on what gets published.

New model quick - not a lot to prevent new ideas - no bias in what gets published - but that means that quality of what gets published can be lacking.

My 2c of speculative opinion.

Mark C.

[CraigS]

Originally Posted by mjc

Old model slow - difficult to introduce new ideas - bias can exist on what gets published.

New model quick - not a lot to prevent new ideas - no bias in what gets published - but that means that quality of what gets published can be lacking.

Yep. I agree.
And it would seem the end result may be the same independent of the path chosen .. ie: accepted or rejected by the scientific community. Via the new model, the debate is more public which means we get more insight into the pros and cons (which I see as beneficial, as its another way to learn rapidly about the topic),

I also think that the length of time for them to publish in books is reduced nowadays, and also has the benefits of:

- giving them reputations and;
- lining their pockets.

If they are as famous as Penrose (because he's published books), AND then they pre-print publish on arXiv, it fast-tracks things even more.

I think its great ! It requires amateurs (like us) to develop different skills though .. as you say .. to weed out the 'wheat from the chaff'.

Interesting.

Cheers