Posts by Mike Hewson

11) Message boards : Cruncher's Corner : Wow it's been a decade for me (Message 138700)
Posted 4 days ago by Profile Mike Hewson
Yes, we will have more than a few Einstein At Home First Decadians* this year ! :-)

Congrats to all, I'll clock in my tenner later on. Imagine that eh? Where does the time go ?

These personal milestones obviously reflect well upon the project, and thus certainly worth a few general observations/reflections :

- the project still exists !

- it has nailed more than a few terrific scientific achievements !

- as a computing entity it has steadily grown in stature and performance !

- it has received genuine positive acknowledgement from professional practitioners in the relevant knowledge domains !

- it has contributed to the professional development of some practitioners !

- it has contributed to the development of distributed computing !

- it has a very bright future on account of the refinement of it's practices and protocols !

ie. pats on the back all around I feel. Or high fives .... seriously all E@H registrants of whatever longevity have provided essential resources, feedback and other valuable involvement that input materially to the above scorecard.

Personally I am recurrently and pleasantly amazed that in a world that presently exhibits more social/political/etc fractures than a grenaded glass factory, such commonality of purpose can be so demonstrated. Plus of course it is a geek/nerd hobby par excellence ! :=)

Cheers, Mike.

* EAHFDs if I may suggest/register a mnemonic ! :-)
12) Message boards : Science : out on a limb without a wave to hop on (Message 138682)
Posted 5 days ago by Profile Mike Hewson
Mike,
I don't understand the part about a neutron decaying into a proton in about a half an hour.

I seem to remember from chemistry, the table of elements. Each atom had a fixed number of protons and a fixed number of neutrons. Maybe my memory is incorrect or there is something else going on here.

Thanks for the explanation of the difference in neutron/protons in terms of the up/down quarks.

'all on it's own'

... is the key thing. It would seem that it needs to keep company in order to not decay. A lone neutron is unstable. Weird huh ? Unless disturbed/nudged a lone proton is stable - at least for the lifetime of this universe.

If you look at the periodic table in terms of isotopes - same number of protons, differing number of neutrons - then the most stable forms of each element tend to have a mild excess of neutrons. Though nuclei which are called even/even - multiple of two protons and multiple of two neutrons - are especially stable. Now you can bash anything to bits if you whack it hard enough so stability here is measured by the amount of energy required to break something up ( hence the older term 'atom smashing' ). It it falls apart simply because you watched and waited then the decay is termed as spontaneous. Very stable means I have to really clout it in order to see pieces. Now even/even nuclei are also multiples of the helium 4 nucleus - two protons + two neutrons - otherwise known as the alpha particle when seen alone ( helium atom stripped of electrons ). In any case nature seems to like multiples of alpha particles .... or failing that an extra neutron or two ! :-)

Some nuclei are just hopeless for stability. Francium for instance, and this applies to most of it's isotopes, can barely last a second. But a few of it's isotopes will stay around for a half hour. In fact the term 'metastable' is sometimes applied to refer to not instantaneous breakup, but not very much longer lived either! It took years to characterise because it simply fell apart in your fingers, as it were. So Francium ( 87 protons ) is an example of the group of odd/odd nuclei which - you can now guess - are all pretty rubbish at stability, certainly with respect to those nearby to them in the table.

Cheers, Mike.
13) Message boards : Science : gravitational waves and the general theory of relativity for reptiles (Message 138657)
Posted 6 days ago by Profile Mike Hewson
Thanks for reading my notes. Also I thank you for the reference. Reading the reference has led me to a possible line of exploration. As it is now the observations to date have focused on objects discernable and measurable via a given lens effect observation. Thus the article and the analysis of quasars and objects and the time differences caused by gravitational stretching and slowing. Hence the differences.

What would be intriguing would be to time plot lens observations in far apart lenses and in effect seek coincidence in these distant part of the sky observations. That would then perhaps lead to some other "x-factor" impacting the lens effect other than the already postulated smearing of a given lens. Discovery of coincidental time overlaps might lead one to have discovered a means of discerning gravitational waves...

Absolutely. What you propose has an analogous effort at radio wavelengths, going by general moniker of 'high resolution pulsar timing arrays'. The idea here is to characterise very many pulsars in their 'usual' measurements - including their individual quirks etc - and maybe one day note that the signals from them have coherently altered across the group. This leads to the sensible conclusion that they haven't all conspired to fool us by altering their behaviour at source, but that gravitational waves have passed us by causing our local perception to change. Now the technical challenge is to be sufficiently precise with observations in order to ( eventually ) be confident about an effect.

Cheers, Mike.
14) Message boards : Science : Plans for near future of E@H ? (Message 138656)
Posted 6 days ago by Profile Mike Hewson
I decided to bite the bullet and get a copy of the 'Handbook Of Pulsar Astronomy' by Lorimer & Kramer. I expect that will keep me busy for a while. Having only finished the first - introductory/overview - chapter, the field reminds me of lepidoptery ie. the study of butterflies and moths. I don't mean that in any derogatory sense at all, but rather what a wonderful collection of objects in the pulsar category are out there, and boy are there some weird astrophysical gadgets operating ! I have this image in my mind of these fast, dense rotors just showering sparks all over the neighborhood ie. what a wild place must be the surface of a neutron star. I also note how hungrily one can study all meaningful aspects of the radio emission properties. So far it seems quite well written, not too much of a brain strain. I just have to quote this ( I'm assuming a wee bit tongue-in-cheek ) comment about galactic pulsar distributions :

Although the clustering of sources around the Sun seen in the left panel of Figure 1.9 would be consistent with Ptolemy's geocentric picture of the heavens, it is clearly at variance with what we know about the Galaxy ......



In any event it has already settled my mind about dispersion effects. As this graphic illustrates :



the propagation delays can span several pulse cycles. The other thing that especially strikes me while reading is that neutron stars, being nearly black holes as it were, retain EM visibility for behaviours that may demonstrate really high gravitational field strengths ( yes, I know that is an obvious comment ).

Cheers, Mike.
15) Message boards : Cafe Einstein : Cafe Einstein: LPTP Triskaidekaphenia (Message 138650)
Posted 6 days ago by Profile Mike Hewson
I always hear how the gas price is highest in parts of Cali

Last week I filled all of my cars up when the price dropped to $1.89 but it is already back up to $2.35 again

Yeah. About a month ago the retail standard 95 octane dropped about 40% in price, pretty much overnite, and now has rebounded up about 10%. So it's around $1.20 AUD per litre now. I don't drive any further though ....

Cheers, Mike.
16) Message boards : Cafe Einstein : Cafe Einstein: LPTP Triskaidekaphenia (Message 138647)
Posted 6 days ago by Profile Mike Hewson
Now that I come to think of it : I started the medical course in January 1980 .... oooh, I see your point. :-0

Cheers, Mike.

( edit ) ... and this from a guy who used to jump out of planes for a living ? Like that's easy, right? There is no way that you'd miss the planet. Your work's already done for you from the get go ... a lazy use of gravity if you ask me ! :-):-)


So as to not hijack the science thread, I'm continuing here.

@Mike - I not sure I would say the work is already done for the jumper, lol. I would describe gravity as a harsh task-master who will not be denied. Ask any paratrooper who has had a major 'chute malfunction (happened to me twice) how "weak" gravity is. After the initial thought of, "Oh crap, this is gonna hurt" goes thru your head you get busy figuring out how not to bounce.

Well, one out of two ain't bad. Hence the bad discs in my spine. The first time my 'chute re-inflated and I lazily (see above) floated to the ground. The second time it was about halfway full of air when the dang planet got in the way. So on that count, you are correct. I didn't miss. I just ended up with a few big ouchies.

On further reflection, after re-reading your response, I now claim to have a perfect record as a paratrooper. I jumped 54 times and hit the Earth every time, even though it is moving thru space at around 18 miles per second. Not bad, huh?


I think the idea is that if you have done N jumps then you would be fit for N+1, perhaps that's a better definition of success ! :-)

My flying instructor used to quote the old saw : a 'good' landing is one you walk away from. The other one I liked was : when the engine loses power the plane belongs to the insurance company, so focus on making a good landing ( ie. as above ). He had others : there are old pilots, bold pilots, but few old and bold pilots ( ie. don't do aerobatics under 10K feet, or alternatively just don't do aerobatics ). Also : there are three useless things in flying (a) the runway behind you (b) the airspace above you and (c) the fuel in that tank on the ground down there. Plus : it is better to be on the ground wanting to be in the air, rather than in the air wanting to be on the ground ( ie. stay on the ground in lousy weather ). His best one was very specific, 'if you get in one of these :



... I will smack you down'. It's an uncertified device, officially classed in the 'ultralight' category and thus escapes independent expert attention. Typically flown by 'air libertarians' who tend to buzz private properties for a lookie, and appear to think no-one will be beneath them when they crash. Mind you, no incident to date involving them has called upon acute medical or rescue services.

Speaking of buzzing : what's the go with all those little drones ? I see a big market opening up for anti-drone products. :-)

Now wandering around the SpaceX website with Elon Musk's idea of colonising Mars, it occurs to me that there may be a vague queue forming for people to do this. I can't think of anything more terrifying.

I think the Cutlass was undergoing some test. Probably to see if it would fly of a carrier. It had those immediate post WWII jet engines which were notoriously under-powered.

Cheers, Mike.
17) Message boards : Cafe Einstein : Jumbled Word Game #5 (Message 138615)
Posted 7 days ago by Profile Mike Hewson
Darn possums ! Beaten by a superior counter-intelligence manoeuvre.

'Crab Count' ? What is this : Deadliest Catch ?

As for the rest, well safety first in the stationery cupboard huh? My nearest/dearest Linda concurs. T'is many a computer case ( with the little sharp metal edges just on the inside ) that I have left my blood within. DNA for later forensics, the ultimate signature.

Deserves a +3 without question :)))

Don't tell me. This is like QI with Stephen Fry, in total I am way in the negative in any case ! :-)

I'll also say... that none of the words so far postulated... have started with the correct letter... :)

So that gives an 'E' or an 'R' first then ....

Cheers, Mike.
18) Message boards : Science : out on a limb without a wave to hop on (Message 138614)
Posted 7 days ago by Profile Mike Hewson
Now that I come to think of it : I started the medical course in January 1980 .... oooh, I see your point. :-0

Cheers, Mike.

( edit ) ... and this from a guy who used to jump out of planes for a living ? Like that's easy, right? There is no way that you'd miss the planet. Your work's already done for you from the get go ... a lazy use of gravity if you ask me ! :-):-)
19) Message boards : Cafe Einstein : Cafe Einstein: LPTP Triskaidekaphenia (Message 138610)
Posted 7 days ago by Profile Mike Hewson
Cutlass ? One of these then :



:_)

We did have an aurora the other evening, quite bright and sort of .... well .... looking rather menacing to be quite honest. Which was strange 'cos it was in our Northern sky. I thought it was most unusual and approaching omen-level/dream-time significance. I mean, what would generate that amount of energy from that direction ???

*glare in general direction of Australia*


Oh.

Cheers, Mike.
20) Message boards : Science : out on a limb without a wave to hop on (Message 138609)
Posted 7 days ago by Profile Mike Hewson
Is nuclear a separate field?

Yes. Two actually. The weak and the strong.

The weak has been combined with electromagnetism as the 'electroweak' force. It is involved in nuclear decays for instance. The basic event ( at everyday energies ) is the decay of a down quark into an up quark with the release of an electron and a neutrino type. This is why a neutron ( 2 downs + 1 up ) all on it's own will decay to a proton ( 1 down + 2 ups ) in about a quarter of an hour, on average. Inside nuclei there are various similar reactions. It is called 'weak' due to it's intrinsic strength being above gravitation but below electromagnetism. It is very short range of the order of nuclear dimensions.

The strong is the strongest of all. It's range is of the order of a proton/neutron width. It has this weird behaviour of getting weaker if real close in and getting stronger further out. To separate a group of quarks to individual ones would require infinite energy. So that doesn't happen. What does happen if separation is attempted is the creation of more quarks. So they've only been seen in relatively stable groups of two or three, sometimes as very short lived 'jets' of very many. A legitimate question is 'how do we know what quarks are if we never see them alone ?' The answer is moderately complex. If one fires, say electrons, at protons then there will be close encounters b/w the electrons and the quarks and the results can be studied. Over very many such interactions one can deduce the quark parameters that would consistently give the observed outcomes.

[ One especially interesting result here is that a down quark has mass/energy of ~ 5 Mev and an up has ~ 2 Mev. So a neutron's mass/energy from such 'valence' quarks ought be ~ 12 Mev. This is way lower than the ~ 940 Mev as measured 'on the outside' as it were. The remaining mass/energy is that of the strong interaction, or put another way, the energy of the gluons .... ]

Gravitation operating at great distances and nuclear operating at small distances.

Electromagnetism is also long range.

.... my curiosity just won't quit ....

Excellent! :-)

Why does current thinking seem to be so much against, action at a distance. I grew up in the 50's thinking just that. Stars, planets, etc. They simply tugged at each other and the bigger guy won the most influence in this totality. I know I have nothing to base it on but it just seems that GW doesn't make sense.

I've delayed answering this because I've had to think 'well, what is the problem here?'. Exactly why* does action-at-a-distance ( call it AAAD ) fail ? I'm going to have a longer think about that before replying. I want to identify and isolate the key components better ...

When you want to quit this Mike, I shall understand completely.

It's fine. You ask good questions ... :-)

Cheers, Mike.

( edit ) So the forces are ranked ( strongest to weakest ) :

strong nuclear > electromagnetism > weak nuclear > gravity

... with the method of ranking being a wee bit obtuse in everyday terms, but is defined in terms of constants that determine the degree of 'coupling' between the matter particles and the relevant force carrying particles. NB also that matter particles are under the heading of 'fermions' with the force mediators being 'bosons'. Essentially fermions cannot be stacked together in the precisely the same place : if there are two or more, one of more of them has to move on. Which is good as the matter of the entire universe would wind up all in the one spot otherwise. Whereas bosons can be grouped together, or not, as you please.

* Such exercise is good for the psyche and soul. I've been reading a recent book by Jim Baggott called Farewell to Reality: How Modern Physics Has Betrayed the Search for Scientific Truth ( it seem you can only publish a book - perhaps in the USA at least - only if it has several titles ). While naturally bagging string theory as prediction failure par excellence, it also has a crack at a number of other theory topics too. It's not so much that theory awaits proof/disproof on some experimentalist's workbench, but that some theoreticians actually believe physical demonstration may be foregone and the moniker of 'science' still applied. It seems the string theory rot is spreading. Recurrent readers of my posts will note that I do keep going on about this. This is probably my medical training & background. I literally cannot imagine practising medicine in a likewise reality-be-damned manner ....


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This material is based upon work supported by the National Science Foundation (NSF) under Grants PHY-1104902, PHY-1104617 and PHY-1105572 and by the Max Planck Gesellschaft (MPG). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the investigators and do not necessarily reflect the views of the NSF or the MPG.

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