Wednesday, September 14, 2011

And yet it moves

This September, it's been 16 years since I started studying physics. That's 2^2^2 years which have gone by and bye. Stefan started in 1987. The first physics headline I can recall consciously taking note of was the 1995 discovery of the top quark, and Stefan cites inspiration by the Supernovae 1987a. This got us into a conversation about the most striking insights physics has delivered since we went to university. Here are our winners:

The biggest surprise for everybody except Raffael Sorkin was that the Cosmological constant is not zero. Since 1998, evidence has been adding up and up that our universe undergoes accellerated expansion caused by a small, positive cosmological constant. For more, read my earlier post on the Cosmological Constant and its cousins.

When I was a graduate student, physicists were still debating whether black holes exist or if black holes are just a mathematically possible solution to Einstein's field equations that is however not realized in nature. The first evidence was available already back then, but it took a while for more observations to be made and gradually everybody came to accept that black holes exist for real. (Well, almost everybody.) For more on black holes, see here.

Suspected by many, it still took several decades to unambiguously show that neutrinos have mass. Due to the neutrinos' weak interaction, many years of data had to be collected over different propagation distances at different energies. It wasn't until 2001 that the option of decay rather than oscillation could be ruled out by the SNO results. Yet, the neutrino sector of the standard model still has some mysteries to offer.

In my quantum mechanics class, EPR-type tests of Bell's theorem were Gedankenexperimente. Now they are reality. So are other tests of the foundations of quantum mechanics, down to single photons, double-slit experiments with atoms, while our understanding of entanglement and decoherence has increased and superpositions of larger and larger molecules succeed.

And on the computational side, amazing simulations of large scale structure formation have become possible. If you haven't seen the Millenium Simulation, it's time well spent.

The recent issue of Physik Journal (the membership journal of the German Physical Society) has an article "Physik im Aufwind" that summarizes recent statistical trends in physics. The below shows the number of beginning students in physics by year. I started in the middle dip. It is good to see that physics is drawing in more young people again.

25 comments:

Arun said...

Yet, the neutrino sector of the standard model still has some mysteries to offer.

And no link! Calling out for a blog post!

Phil Warnell said...

Hi Bee & Stefan,

”It is good to see that physics is drawing in more young people again.”

And how this article of yours has me wish that it could be possible that I was made young again so I’d might be among them. However on the positive and possible side The Stephan Hawking Centre at Perimeter Institute has its grand opening in a few days so that there may be some additional spaces for those that have.

Best,

Phil

Phil Warnell said...

Hi Bee & Stefan,

I forgot to mention that I have a ticket to a guided tour on Sunday; that is with the drywall on ;-)

Best,

Phil

Plato said...

Phil,

On your way into the PI Institute Phil do not forget to take a picture of "the saying over the door" if there is one that exists?

Best,

Steven Colyer said...

Have fun, Phil! And take video, not just pictures.

This was enjoyable, Bee. It would be great if you and Stefan could extrapolate forward the next 16 years and what you two expect to see.

Yes, the increase in younger people getting into physics is encouraging. I wonder if there will be enough jobs for them post-graduation, though. Still, a Science or Engineering degree encourages one to think logically and critically, vital in the upcoming (current?) War on Anthropomorphic Climate Change Denial.

Neil Bates said...

Yes, exciting times and Bee and Stefan have done a good job writing about it all. I note some things:
1. The problem of dark matter, unless it's a banality like cold dwarfs (such ideas not viable anymore?) is a major challenge to physics and most people don't realize it. Am I right to say that whatever DM is, it's probably not part of the standard model? I don't know if "axions" would be, or if they're still viable.

2. Despite pretensions from some, we don't really understand what happens in quantum mechanics. The loss of phase coherence should not really lead to isolation of a specific outcome, but rather just to a more disorderly combination of states. As for MWI, the worst pretension there is the claim it just means letting the wave function evolve according to the Schroedinger equation. No, because the SE also represents a specific mass-energy, and is inconsistent with a full particle mass ending up in more than one place - even if tricked up with talk of phase relations, conservation applying in a given world (but if the SE just continues, there is only one world with that evolution - represented as a given amount of mass-energy undergoing distribution in time.)

Uncle Al said...

Happy 10hex^th anniversary!

http://straytats.com/
Surprise your friends. Celtic knots, or maybe Calabi-Yau.

"The Cosmological constant is not zero." If Type Ia supernovae are dimmed by metallicity, then early Type Ia are brighter than the standard candle and closer than assumed. Reset to zero.

"superpositions of larger and larger molecules succeed." Silanize a small virus and go for it - diffracted life! Mild aqueous alkali, ammonia, or fluoride to desilanize, then... infect! Will the maximum infection rate be opposite the minimum of contagion? Weaponize. "We can't tell where it is coming from."

Physics 100% blunders with chirality. When cobbled together, physics really socks. "8^>)

Amitabha said...

What, according to Rafael Sorkin was the biggest surprise, do you know?

Amitabha said...

What, according to Rafael Sorkin, was the biggest surprise, do you know?

Luke said...

Phil,

Enjoy the new building! It's quite nice.


Bee,

"It is good to see that physics is drawing in more young people again."

Yes. I've noticed the physics classes are getting larger all the time!

Amitabha,

HA! That's a good question. I should ask him next week.

Bee said...

Amitabha: I don't know. Let us hear what Luke reports :o) Best,

B.

Bee said...

Hi Neil,

Yes, these are interesting points, but this wasn't a post about questions, but about answers. That dark matter exists has been known for a long time, and we still don't actually know what it is. Whether you believe there's something in QM that we don't understand depends on what you require of a theory. Best,

B.

Bee said...

Hi Steven,

The statistics say that the rate of unemployment among physicists in Germany is very small. Yet, most of them eventually do not work in academia. If that's what you aim at, it doesn't look very well. (And working on a bizarre topic like pheno qg doesn't help either.) The same issue of Physik Journal e.g. also reports that there is a shortage of physics teachers. Best,

B.

Phil Warnell said...

Hi Plato ,

I will do my best to find that inscription you mention.

Best,

Phil

Phil Warnell said...

Hi Steve,

Sorry to inform that I’m not video capable. However I’m certain the PI staff being far more capable and will have much of it available on their web site. The important thing is this will add a few more opportunities for that growing number of interested. It’s nice to think that although it’s unlikely the next Einstein will be Canadian there’s a better possibility she/he might someday have been given a chance to become known as such perhaps in part as being here.

Best,

Phil

Phil Warnell said...

Hi Bee,

“.... “it's been 16 years since I started studying physics”; I like the way you put that. That would have me take it you mean being a theoretical physicists is as much or more about its study as it is about coming to know it. That is I find it ironic that many seem to think that it’s perhaps the opposite, that the coming to know is what’s most important as being what drives the physicist or anyone for that matter who values the importance of increased understanding.

“Some physicists, among them myself, cannot believe that we must abandon, actually and forever, the idea of direct representation of physical reality in time and space; or that we must accept the view that events in nature are analogous to a game of chance. It is open to every man to choose the direction of his striving: and also every man may draw from Lessing’s fine saying, that the search for truth is more precious than its possession. “

-Albert Einstein, “The Fundamentals of Theoretical Physics” in the journal [Science- May 24, 1940]

Best,

Phil

Luke said...

Phil,

Do you know where they moved that sign? They moved it sometime last year to add the extension but I have no idea where it is now.

Bee,

Hopefully he'll have a good answer! Group meetings haven't started yet on account of all the seminars getting started.

Plato said...

Hi Phil,

Maybe somebody at PI will help in locating the sign?

Also, I must officially saying that at a ripe age now, the tattoo has turned out quite nice.:)

I am continuing research on the historical information as Ancient Greek saids indeed those, "ignorant of the geometry" but am having trouble with the other words....even typing in using alphabetical correlations of Ancient Greek.

I will have an upcoming post on this as I am sure Howard Burton would be interested?:)Maybe? Even others?

Best,

Robert L. Oldershaw said...

Tatooine should not exist.

But there it is.

Doing what Platonic idealizations say is impossible.

Magnificent perfection!

Plato said...

Uncle Al you've been following in regard to Supenovas....thanks.


Kepler 16-b: A Planet With Two Suns

It could most certainly could get confusing for you Robert in regard to the shadows?:p)

Best,

Phillip Helbig said...

"The Cosmological constant is not zero." If Type Ia supernovae are dimmed by metallicity, then early Type Ia are brighter than the standard candle and closer than assumed. Reset to zero.

First, to first order more distant supernovae are observed to be dimmer than otherwise expected, so your effect, even if it exists (do you seriously think no-one has considered it), works in the wrong direction.

Second, the supernovae stuff isn't the only indicator of a positive cosmological constant. In fact, though no one test pins it down, looking at all the other tests results in a compatible value.

Phillip Helbig said...

"The problem of dark matter, unless it's a banality like cold dwarfs (such ideas not viable anymore?)"

Assuming you mean stars, they are made out of baryons, and so excluded by constraints from big-bang nucleosynthesis. Have been for years if not decades.

Plato said...

Cosmic Explosion is New Candidate for Most Distant Object in the Universe

Amitabha said...

Luke,

Thanks! I will be interested. Actually I didn't know that Rafael had been expecting a non-zero cosmological constant -- I would be interested to know why he expected that in the first place!

Amitabha

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