Jan 292016

Eons ago, back when dinosaurs still roamed the Earth, George W. Bush was still a first-term president, there were only five Star Wars films and Java applets were still cool, I created an applet that showed what Mars would look like if its surface was covered by oceans.

I liked what I did so I added the capability to use other data sets, including data sets for the Earth.

The applet is worthless now, or almost so. Java applets are no longer supported in Google’s Chrome browser. They were never really supported on mobile platforms. Even in browsers that do still support Java, the user has to go through hoops and add my domain as a security exception (not recommended) to allow my unsigned applet to run; all this a result of vain attempts to address the security risks inherent in Java and its implementations.

Anyhow, the applet still works if you can run it. And this is what the Earth looks like today:

Someone recently asked what our planet would look like if it was devoid of oceans. If sea levels were 5000 meters below the present value, the planet would still have a shallow ocean in place of the Pacific. Otherwise, though, it would be mostly dry land with only some inland seas where the Atlantic and the Indian oceans used to be.  It would be possible to walk from pole to pole without wetting your feet; however, you might get a tad thirsty along the way, and there’d not be much rain either.

Decrease ocean levels by another 1000 meters to 6000 below present sea levels, and the last remaining ocean is gone:

Finally, at 7000 meters, the only open water that remains would be in places of the deepest ocean trenches. (Mind you, even then, some of these seas would still be up to four kilometers deep.)

I was also asked what things would look like if the seas rose. There is a surprising amount of change to coast lines by an increase of a mere 50 meters:

Florida is gone; Western Europe looks noticeably different. Increase the sea level rise to 200 meters, and now the change is rather more dramatic:


India is now an island or almost so (there may be some land bridges connecting it to the Asian continent that are too narrow to be visible at this map’s resolution). Much of Europe, Russia, Australia, South America, and the eastern parts of North America, gone.

Finally, at 1000 meters, only mountain ranges remain:

With this little dry land left, there is not much in the way of storms; like Jupiter with its Great Red Spot, the Earth might also develop long-lived storms that circumnavigate the planet many times before dissipating.

 Posted by at 3:30 pm
Jan 282016

If you are not following particle physics news or blog sites, you might have missed the big excitement last month when it was announced that the Large Hadron Collider may have observed a new particle with a mass of 750 GeV (roughly 800 times as heavy as a hydrogen atom).

Within hours of the announcement, a flurry of papers began to appear on the manuscript archive, arxiv.org. To date, probably at least 200 papers are there, offering a variety of explanations of this new observation (and incidentally, demonstrating just hungry the theoretical community has become for new data.)

Most of these papers are almost certainly wrong. Indeed, there is a chance that all of them are wrong, on account of the possibility that there is no 750 GeV resonance in the first place.

I am looking at two recent papers. One, by Buckley, discusses what we can (or cannot) learn from the data that have been collected so far. Buckley cautions researchers not to divine more from the data than what it actually reveals. He also remarks on the fact that the observational results of the two main detectors of the LHC, ATLAS and CMS, are somewhat in tension with one another.

Best fit regions (1 and 2σ) of a spin-0 mediator decaying to diphotons, as a function of mediator mass and 13 TeV cross section, assuming mediator couplings to gluons and narrow mediator width. Red regions are the 1 and 2σ best-fit regions for the Atlas13 data, blue is the fit to Cms13 data. The combined best fit for both Atlas13 and Cms13 (Combo13) are the regions outlined in black dashed lines. The best-fit signal combination of all four data sets (Combo) is the black solid regions

From Fig. 2: Best fit regions (1 and 2σ) of a spin-0 mediator decaying to diphotons, as a function of mediator mass and 13 TeV cross section, assuming mediator couplings to gluons and narrow mediator width. Red regions are the 1 and 2σ best-fit regions for the Atlas13 data, blue is the fit to Cms13 data. The combined best fit for both Atlas13 and Cms13 (Combo13) are the regions outlined in black dashed lines. The best-fit signal combination of all four data sets (Combo) is the black solid regions.


The other paper, by Davis et al., is more worrisome. It questions the dependence of the presumed discovery on a crucial part of the analysis: the computation or simulation of background events. The types of reactions that the LHC detects happen all the time when protons collide; a new particle is discerned when it produce some excess events over that background. Therefore, in order to tell if there is indeed a new particle, precise knowledge of the background is of paramount importance. Yet Davis and his coauthors point out that the background used in the LHC data analysis is by no means an unambiguous, unique choice and that when they choose another, seemingly even more reasonable background, the statistical significance of the 750 GeV bump is greatly diminished.

I guess we will know more in a few months when the LHC is restarted and more data are collected. It also remains to be seen if the LHC can reproduce the Higgs discovery at its current, 13 TeV operating energy; if it does not, if the Higgs discovery turns out to be a statistical fluke, we may witness one of the biggest embarrassments in the modern history of particle physics.

 Posted by at 6:25 pm
Jan 282016

There is an interesting paper out there by Guerreiro and Monteiro, published a few months ago in Physics Letters A. It is about evaporating black holes. The author’s main assertion is that because of Hawking radiation, not even an infalling ray of light can ever cross the event horizon: rather, the event horizon evaporates faster than the light ray could reach it, neatly solving a bunch of issues and paradoxes associated with black holes and quantum physics, such as the problems with unitarity and information loss.

I find this idea intriguing and very appealing to my intuition about black holes. I just read the paper and I cannot spot any obvious errors. I am left wondering if the authors appreciated that the Vaydia metric is not a vacuum metric (indeed, it is easy to prove that a spherically symmetric time-dependent solution of Einstein’s field equations cannot be a vacuum solution; there will always be a radial momentum field, carrying matter out of or into the black hole) but it has no bearing on their conclusions I believe.

Now it’s a good question why I am only seeing a paper that is of great interest to me more than six months after its publication. The reason is that although the paper appeared in a pre-eminent journal, it was rejected by the manuscript archive, arxiv.org. This is deeply troubling. The paper is certainly not obviously wrong. It is not plagiarized. Its topic is entirely appropriate to the arXiv subject field to which it was submitted. It is not a duplicate, nor did the authors previously abuse arXiv’s submission system. Yet this paper was rejected. And the most troubling bit is that we do not know why; the rejection policy of arXiv is not only arbitrary, it seems, but also lacks transparency.

This manuscript archive is immensely valuable to researchers. It is one of the greatest inventions of the Internet era. I feel nothing but gratitude towards the people who established and maintain this repository. Nonetheless, I do not believe that such an opaque and seemingly arbitrary rejection policy is justifiable. I hope that this will be remedied and that arXiv’s administrators will take the necessary steps to ensure that in the future, rejections are based on sound criteria and the decisions are transparently explained.

 Posted by at 5:51 pm
Jan 282016

This is NASA’s week of tragedy.

Today is the 30th anniversary of the loss of the space shuttle Challenger with seven souls on board. One of my notable memories of this event is that it was the first time that I recall that the national broadcaster in then still communist Hungary didn’t dub a speech of Ronald Reagan. I think the speech was actually carried live (it took place at 5 PM EST, which would have been 11 o’clock at night in Hungary; late, but not too late) and it may have been subtitled, or perhaps not translated at all, I cannot remember. For me, it was also the first disaster that I was able to record on my VCR; for days afterwards, my friends and I replayed and replayed the broadcasts, trying to make sense of what we saw. (Sadly, those tapes are long lost. My VCR was a Grundig 2000 unit using a long-forgotten standard. After I left Hungary, I believe my parents used it for a while, but what ultimately happened to it and my cassettes, I do not know.)

Yesterday marked the 49th anniversary of the Apollo 1 fire that claimed the lives of three astronauts who were hoping to be the first to travel to the Moon. Instead, they ended up burned to a crisp in the capsule’s pure oxygen atmosphere, with no chance of escape. Arguably though, their tragedy resulted in much needed changes to the Apollo program that made it possible for Apollo 11 to complete its historic journey successfully.

And finally, in four days it will be exactly 13 years since the tragedy of Columbia, which disintegrated in the upper atmosphere at the conclusion of a successful 16-day mission. I remember that Saturday all too well. I was working, but I also had CNN running on one of my monitors. “Columbia, Houston, comm check” I heard many times and I knew something already that those in the mission center didn’t: CNN was already showing the multiple contrails over Texas, which could only mean one thing: a disintegrating vehicle. And then came the words, “Lock the doors”, and we knew for sure that it was all over.

Of course the US space program was not the only one with losses. The Soviet program had its own share of tragedies, including the loss of Vladimir Komarov (Soyuz 1 crash, April 24, 1967), three astronauts on boar Soyuz 11 (depressurization after undocking while in space, June 30, 1971), and several deaths on ground during training. But unlike the American cases, these Soviet deaths were not all clustered around the same date.

 Posted by at 3:35 pm
Jan 272016

I was never a fan of conspiracy theories. Most popular conspiracies are highly improbable: maintaining complete secrecy would require thousands of people to cooperate for many years.

But just how improbably are conspiracies, really? Well, now there is a quantitative estimate, thanks a paper by David Robert Grimes. Grimes used several specific, high-profile cases of actual conspiracies to estimate the likelihood that a conspiracy is revealed by a participant. He found that while the probability that any individual participant betrays the conspiracy may be quite small, the likelihood that the conspiracy is revealed over time nonetheless approaches unity over the years, as demonstrated by the following diagram:

The parameter p in these curves represents the probability that any given participant will break his silence in a given year.

So then, this is it… by Grimes’s calculations, if the Moon landing had been a hoax or if similarly, vaccination or climate change were both just vast conspiracies, these would all have been revealed with a very high likelihood in the span of no more than a few years.

None of this will deter conspiracy theorists, I am sure. If all other arguments fail, they’ll just declare Grimes himself to be a member of the conspiracy, too. Well, for all you know, I may also be an agent of the secret cabal, using my blog to lure the unsuspecting into believing that man walked on the Moon, that vaccines save lives or that anthropogenic climate change is actually happening…

 Posted by at 5:28 pm
Jan 202016

One of the blessings of being self-employed is that I don’t need to read IT job advertisements on a regular basis.

But for those friends of mine who do, I just came across this gem that helps translate the common buzzwords and catch phrases that appear in these ads:

Don’t let any of this deter you from going after that position… just tamper your expectations.

 Posted by at 6:22 pm
Jan 142016

Recenly, there was a particular piece of music that caught my attention on CBC’s The Signal: Sapokanikan by Joanna Newsom.

The song begins with the lines,

The cause is Ozymandian
The map of Sapokanikan
is sanded and beveled
The land lone and leveled
By some unrecorded and powerful hand.

This made me re-read Shelley’s timeless poem about the ruined statue of Ozymandias in the desert:

‘My name is Ozymandias, king of kings:
Look at my works, ye Mighty, and despair!’
Nothing beside remains. Round the decay
Of that colossal wreck, boundless and bare
The lone and level sands stretch far away.

And then here is a real-life Ozymandian tale from a few days ago, from China: A 37-meter tall golden statue of Mao erected in the middle of nowhere.

The ending, however, is different: After the statue has been ridiculed on Chinese social media (with many quoting from Shelley’s Ozymandias) the statue was hastily demolished. Wisdom has not yet departed the Middle Kingdom, it seems.

 Posted by at 2:08 pm
Jan 062016

I’ve become a calendar boy.

Or to be more precise, an illustration in a paper that my friend and colleague, Eniko Madarassy and I published together early last year in Physical Review D found its way to the 2016 calendar of the American Physical Society.


Now if only it came with perks, such as getting a discount on my APS membership or something… but no, in fact they didn’t even bother to tell us that this was going to happen, I only found out today when I opened my mailbox and found the calendar inside. Oh well… It was still a nice surprise, so I am not complaining.

 Posted by at 2:35 pm