* Posts by John Mangan

134 posts • joined 14 Aug 2007

Page:

Let's grow a baby universe in a supercomputer, watch black holes collide

John Mangan

I have a question . . .

"They are predicted to have formed in the early universe from massive dense clouds that collapsed straight into black holes without forming any stars and galaxies beforehand"

I have seen this mentioned a number of times recently and I'm wondering how is this supposed to happen? My vague memories suggest that as the gas collapses it heats, nuclear fusion starts, radiation slows the inflow of matter (or dissipates it into the outer reaches of the 'system'. Does this model depend on matter falling in such large volumes and so rapidly that it snuffs out the nascent star?

0
0

Why you should Vote Remain: Bananas, bathwater and babies

John Mangan

Re: "Let's not be that third" - Why not ?

Think . . neither can afford to get both hands out the others pocket but if they both keep one hand each in then they both have a hand free for the third party.

It's really not that hard.

3
0
John Mangan

Re: "Let's not be that third" - Why not ?

Read the line - does not get plundered *separately*

1
0

Gravitational waves: A new type of astronomy

John Mangan

Re: How powerful is a gravitational wave close to the source?

@Ken Strain - Ken, it is indeed I. And I'm very glad to see you haven't had to correct any egregious errors on my part. It's been a long time and the memory's not what it was. I re-read my thesis after the announcement of the first detection and it really brought home how much I had forgotten..

Oh, and congratulations of course to everyone in Glasgow!

1
0
John Mangan

Re: How powerful is a gravitational wave close to the source?

It's an interesting question - and I don't know the answer - but you need to consider that such a proposed planet has to be far enough away from both black holes not to have been ripped apart by tidal forces (which will be far more powerful than the tidal forces of any gravitational radiation emitted by the system) so I am going to say - at such a distance - still pretty negligible.

0
0
John Mangan

Re: What a time to be alive

"I wonder how they arrange it so that, say, a nuke going off in North Korea doesn't disturb the mirrors by such a tiny amount?"

Basically the nuke will generate 'ringing' at one set of frequencies and the detector will be sensitive at different frequencies. Also if there a coincident signal at two or more detectors in the right frequency range there are plenty of seismometers (including at the sites of the detectors) to throw up a 'just check this would you?' alert. Then you look at amplitudes, frwquencies, attack, decay, etc.

1
0
John Mangan

Re: Poor science - @Dr Mouse

"However, aren't there quite a lot of other variables to consider? If there's a large sun between us and the event (a sun which passed across the wave front) then wouldn't that distort the wave? So, I would imagine that large events produce such enormous waves that other objects in their path have limited impact but I'd also imagine that there will come a point where it is like looking at the waves on the shore... so many that it's basically noise with no useful information."

Not really. The waves are quadropoles and therefore will be pretty well unaffected by a 'monopole' object (not the best scientific explanation but I think gives a clear image of what is happening).

Also for your second point the waves are incredibly weak to start with, energy falls off according to 1/R^2 as they expand spherically and therefore 'soon' fade into undetectability. Also there is no 'shore' for them to be reflected from (current modesl, etc.)

3
0
John Mangan

Re: Poor science

@John Sager - "gravitational radiation has only been measured by one method". Not entirely true. If you are referring to direct measurement I will grant you the point. However I believe that the energy loss of certain pulsars has been calculated to match what would be predicted by GR for gravitational radiation - so an indirect detection and not for the same sources.

4
0

Cold space gas? Sure, supermassive black holes can eat that. Nom, nom, nom

John Mangan

And another question . . .

"Cold gas raining in . . " sounds like a purely radial flow which makes me wonder what conditions give rise to gas with no angular momentum?

Also, as the gas gets closer to the super-massive black hole presumably it is accelerated and compressed and so becomes 'hot'. So wouldn't any gas actually seen falling into a black hole be hot and, if so, how can anyone know that previously observed infalls weren't cold gas as well (originally). What criteria are being applied here?

0
0

Mars One puts 100 Red Planet corpses colonists through fresh tests

John Mangan

Re: Anyone see the program Ascension?

Yes, it was shit!

On so many levels and for so many reasons.

Thanks for asking.

2
0

UK Home Office is creating mega database by stitching together ALL its gov records

John Mangan

Re: RE: "one database to rule them all"

I truly wish I could believe that.

I tend to side with the view that most of these people are doing the best job they can and are looking at efficiency, savings, etc. but if anyone of a totalitarian disposition every does get into power with these tools to hand then we are all well and truly f@cked on a scale never before seen in human history.

9
2

Would we want to regenerate brains of patients who are clinically dead?

John Mangan

Re: ick, ethicists

Agreed with you right up to the reckless, ill-considered

" In the short term, we should be reviving bodies left and right despite whatever horrifying outcomes are encountered due to damaged brain tissue. Hopefully they signed consent forms beforehand, but that is just a courtesy"

No, there have to be checks, balances and forethought!

7
0

NIST readies 'post-quantum' crypto competition

John Mangan

Re: NIST is being prudent

Sometimes stuff can arrive sooner than you think - and betting that it won't would be much more of a mug's game than putting in a little ground work in preparation.

3
0
John Mangan

The trouble with 'random' ideas . .

is that they are no use for the frequent, reliable transfer of information. Although what you are suggesting would probably work very nicely for a single communication, or set of communications, with a known other (who knows what tricks you are pulling) it would not work as a widely available communications system where standards have to be created, agreed to, implemented and therefore become common knowledge and easily reversed.

The reason we rely on maths is because it provides a known method for reducing structured information into essentially random data together with a key that can be shown to be breakable only by the application of 'n' clock cycles and that 'n' can be adjusted to whatever level of security you require (bugs and implementation errors excepted).

6
0
John Mangan

Re: I find it heartening . .

To be fair it has been 'quite a few' if not yet 'many years'.

1
0
John Mangan

I find it heartening . .

. . that before an encryption apocalypse is upon us there are already several avenues of investigation open because mathematicians (I assume) 'wasted' their time with developing branches of Number Theory that most people would look at and say, "What's the use of that?".

Anyone responsible for science funding should take lessons from these sort of developments.

5
0

Mercury to transit Sun: Viewer discretion advised

John Mangan

Re: Can someone explain . . .

The magic of geometry . . a quick scribble reveals that little 7 degrees can throw Mercury up to 11 times the Sun's radius above/below our orbital plane. Apparently Mercury's orbit isn't as really, really close as I thought.

8
0
John Mangan

Re: Can someone explain . . .

. . . or does a 'transit' demand it cross at least, say, 90% of the transited object?

1
1
John Mangan

Re: Can someone explain . . .

But don't the relative sizes and positions allow for quite a lot of non-coplanarity and still let you see Mercury doing its dash?

1
1
John Mangan

Can someone explain . . .

why, if Mercury whizzes around the Sun every 88 days, and Earth and Mercury both orbit in the same plane, and tiny, tiny Mercury is really, really close to really big the Sun that a transit only happens 13 times a century rather than, say, four times a year?

Thank you.

2
2

One black hole, three galaxies, four BEELION solar masses – found by accident

John Mangan

Re: Simple question

Okay I'm definitely not an expert but:

There is a fundamental problem that universe is an archaic term for when we thought what we could see was all there was. That is no longer the case but we still call what we can see (by whatever physically allowed means) the universe. it is, by definition, the only one we can 'know' about.

There are, as you have surmised, several possibilities for other 'universes'. An incomplete list includes:

- universes beyond the observable horizon. There are some theories which allow some inferences to be made from movements of matter within our observable uinverse.

- multiple universes existing in various branes in the multi-dimensional M-theory

- multiple universes generated by (or causing indirectly) quantum weirdness (take your pick).

. . . . and others.

You have selected a specific sub-set of universes that you are happy with and arrived at a (possibly valid) conclusion based on that alone.

As one of the other posters alluded to there are very many books, programmes and web articles on these subjects and you need to do some investigation of your own before you can ask a question that others will find sufficiently well formed/defined to provide an answer to.

I don't want to come off as patronising because I am only too well aware how short my knowledge in this area falls but (I hope I'm not being too presumptious here) the general tenor of your question implies that you are not.

I probably should post this anonymously . . . .

1
0
John Mangan

Re: Simple question

It's a simple question but the terms are poorly defined.

2
0

'Cat-flap' pendulum offers 7x improvement for grav-wave detectors

John Mangan

Re: Noise Filtering

There are a whole array of isolation mechanisms. There are passive items like lead/rubber stacks, the mirrors are suspended on fine 'wires' to filter higher frequency noise. There are feedback mechanisms using laser beam sidebands to further reduce noise.

On top of that although the impression given is that a laser beam enters the arm, reflects at the end and then exits these arms are actually Fabry-Perot cavities and the light bounces back and forth 'a lot'. The reflectivity of the mirrors define the 'finesse' of the cavity and the 'finesse' also defines the frequency response to gravitational waves. So one photon hitting a bump isn't going to be a big deal.

There are also baffles along the tubes to ensure that scattered light doesn't get to re-enter the beam and (almost certainly) a whole host of other enhancements that weren't even thought of when I left the field nearly three decades ago.

3
0

William Hague: Brussels attacks mean we must destroy crypto ASAP

John Mangan

I find myself wondering . .

. . .if 'terrorists' eschew encrypted communications because they fear they would raise a large flag over any device that sends such messages.

Surely easier and less conspicuous to post on facebook/twitter about "meeting at the 'cafe' on Tuesday. Bring your 'packed lunch'.", and get lost in the morass of other vacuous meanderings filling the intertubes?

8
0

Labour: We want the Snoopers' Charter because of Snowden

John Mangan

Re: More and more . .

I hope you are right - and when the 'Republican Grandees' spoke out against him I expected it to increase his popularity; reinforcing his image as not part of the establishment.

However I fear that a lot of Trump support is based on narrow self-interest and buying into his promise to make America great and get rid of all the immigrants and stop terrorism. I'm aware of the Godwin risk but, in this case, I really do believe the parallels to Hitler are worrying.

However I then comfort myself by believing that Trump is nowhere near as bright as Hitler - which is no doubt how pre-WWII observers comforted themselves when Hitler was seeking election - by comparing him to $ARCHETYPAL_HISTORICAL_BADDY <sad face>.

5
1
John Mangan

Re: More and more . .

I think provable fact is better than a guess - no matter how well founded. It's also a lot harder for governments to ignore said facts and dismiss them as conspiracy theories.

If the US or GB had an ounce of integrity Snowden would be summarily pardoned (by one) or offered asylum (by the other).

25
0
John Mangan

More and more . .

I think that Edward Snowden should be lauded throughout the free world as a modern hero.

Whatever the result of this bill he has, at least, made us all (for a given value of 'all') aware of what is being done behind the scenes and how the government views the governed.

That alone is valuable information.

45
1

Flying Scotsman attacked by drone

John Mangan

Re: Clearly impossible

It's ALWAYS the day for coming out with maths!

6
0

IEEE delivers Ethernet-for-cars standard

John Mangan

When we had our house re-wired we ran CAT5 to every room and use it to convey phone signals to a couple of rooms..

1
0

UK Snoopers' Charter crashes through critics into the next level

John Mangan

Re: This:

. . . . and family and friends? (You know, because you could imply things from collateral information).

1
0

Mars to get comms upgrade with ExoMars mission

John Mangan

Re: The Red Planet's satellite network ..

@Duncan McDonald & TimR

Thanks guys.

And the unexpected titbit that the ?-stationary orbit lies between the orbits of the two moons - not helpful.

0
0
John Mangan

The Red Planet's satellite network ..

Awesome to think that we have created a satellite network around another planet. Hopefully we have learned some lessons from here and will strive to keep the debris levels to a minimum.

Does anyone know how many active satellites are currently in orbit around Mars?

And, although I can understand the transmission power savings by orbiting 250 miles above the surface, what's the altitude for a 'geo'-stationary orbit?

0
0

Microsoft adds 'non-security updates' to security patches

John Mangan

Re: As many PC users think IE is the Internet...

(Hoping I've learnt something from Worral).

I think the desire on the part of a vendor for a monopoly is entirely natural, more profit, but the market naturally suffers if the monopoly is reinforced by unreasonable rules, bonuses or other behaviour.

If the monopolist raises prices too high, or drops quality too low, or restricts supply to greatly, et. then the market should respond by allowing other suppliers to come to market.

2
0

NASA sets the date for Martian robot drilling rig to lift off

John Mangan

Re: "A vacuum leak during low temperature testing ..."

Presumably it depends on the 'failure mode' - explosive/implosive?

1
0

UN rapporteur: 'Bad example' UK should bin the Snoopers' Charter

John Mangan

This!

The more information gathered the more false positives there will be.

It doesn't matter if you whittle them down to the fractions of a per cent of the total individuals involved. Even 0.01% of 70 million people is 7000 people (and their families/friends) potentially having their lives turned upside down 'because'.

Does anyone believe sufficient resources will be provided to include checks and counter-checks to get the figure even as low as this?

9
0

Austrian mayor spunks €40k on virgin-eating dragon

John Mangan

I was quite impressed . .

. . by the cover picture. Very dramatic.

Less impressed by the actual logo - 40k! - I'm in the wrong job. I have no artistic talents that I am aware of but I can swap fonts and change colours with the best of them for, shall we say, 30k (introductory offer because I like your face).

15
0

No more Nookie for Blighty as Barnes & Noble pulls out

John Mangan

Re: I have a local library ...

That's not really true though, is it? Probably for bestsellers, classics and so on but for the smaller titles, niche interest and out of print books ebooks do have an advantage. Also not everyone lives within walking distance of a library, certainly not a main library, and . . . . you have to give them back (that bit actually looks very like the Nook now I think about it).

3
0
John Mangan

Kobo and Calibre + DRM removal

I too prefer paper books. I have some that I bought over forty years ago that have never run out of batteries, failed certificate expiration tests or become obsolete/unreadable formats.

Unfortunately I too have run out of space and resorted to the Kobo because of its multiple format support and the ability to bypass DRM using Calibre. Battery life is excellent, the screen light is superb and the ability to carry dozens of books in a small form factor is brilliant.

I have NEVER paid more for an ebook than for a paperback and bookbub is good if you want notifications of offers that are available.

3
0
John Mangan

Re: a bitter laugh

Upvoted with a heavy heart.

I have never knowingly retrieved pirated content but there are times . . . e.g. sitting through the 'Don't pirate DVDs!' 'feature', for the x^nth time, when I COULD be watching the content I actually paid for that I do wonder . . .

11
0

Windows Phone devs earn double what poor Android devs pocket

John Mangan

Re: Average?

Upvote for your use of 'risible' - not seen frequently enough.

5
0

Lonely bloke in chem suit fuels Mars orbiter

John Mangan

Welcome. . .

. . .amongst the scatalogical and scabrous commentary there is a broad stream of knowledgable and informative content. It's the Registers main saving grace (IMHO).

1
0
John Mangan

Why . . .

. . .are they fueling it a month before launch? Genuine question.

There must be a fair bit of transporting and so on to do before it gets launched so do you really want it full of explosive, toxic crap all that time?

0
0

Boffins' gravitational wave detection hat trick blows open astronomy

John Mangan

Re: So . . . . .

Scott, bear in mind that I am working from near thirty year old memories here but broadly yes.

I remember seeing graphs with a range of postulated sources; Big Bang, supernovae, merging black holes and others thatI've forgotten. Each had predicted ranges for strain and frequency. I'm pretty sure that the Big Bang was low frequency and amplitude because of the elapsed time/intervening expansion of the universe. The longest wavelength/lowest frequency waves will require a space-based detector with 'arms' thousand of kilometres long, see LISA.

I'll have to dig out my thesis to see compare how the predictions from back then compare with the current thinking on the subject (if I can still understand any significant fraction of it).

Other stuff I remember is that the gravitational waves were quadrupoles with two polarisations usually represented as + and x (similar to photons with l and - ). The 'best' signal would be with the wave travelling perpendicular to the detector (up/down into the ground) with the polarisation aligned with the two arms. This gives maximum 'stretch' to one arm with maximum 'squeeze' to the other alternating as the wave propagates.

Exciting times.

1
0
John Mangan

Re: So . . . . .

To get to the oldest waves, and therefore the lowest frequency, will not be possible with ground-based detectors.

That's where LISA comes in . . .

0
0
John Mangan

Re: So . . . . .

I'm well out of date here (and the memory is foggy) but this analogy may be helpful (or completely wrong).

If you drop something into a pool the ripples spread out until they hit a boundary, then they reflect, rinse and repeat until the energy has been evenly distributed around the pool, the boundary, etc. No more ripples.

These waves haven't hit any boundary, they haven't reflected. They suffer from the dissipation of energy as they move from a 'point' source into a larger and larger volume but they are not absorbed, reflected or otherwise homogenated (word?) before reaching us.

0
0
John Mangan

Excited and sad . .

I worked with the Glasgow team as a Postgrad <mumble> years ago and so I am thrilled that this has finally come to fruition. I realised during my studies that I didn't have the patience required to make a career of it (along with other limitations).

I was interviewed by Ron Drever for the post (and worked with him briefly before he moved to Caltech) and I'm desperately sorry to hear he he may no longer be capable of realising his work was so successful.

10
0

Ex-TalkTalker TalkTalks: Records portal had shared password. It was 4 years old

John Mangan

Re: Not just Talk Talk

Actually, I've been called by my bank (First Direct) on two occasions for the purposes of fraud prevention and on both occasions as they started the 'for security purposes . . .' spiel I interrupted with 'You called me, prove who you are." And they did!

0
0

Silent Nork satellite tumbling in orbit

John Mangan

Always an upvote available . .

for a Tom Lehrer reference.

13
0

LIGO boffins set to reveal grav-wave corker

John Mangan

Re: How many events ?

But it depends on what you mean by 'signal'. If you are just talking a 'blip' then yes coincidence would be difficult to rule out. However if you are talking timing, amplitude and signal characteristics (shape, frequency, rise and fall) then it is possible to be very confident with one even from two detectors.

0
0

After-dinner Mint? Stylish desktop finale released as last of the 17 line

John Mangan

Re: Linux & Games

I haven't tried it yet but isn't that what Steam are doing?

6
0

Page:

Forums