Saturday, October 03, 2009

Is Aurora Borealis Caused by Cherenkov Radiation?

First of all, this is not a blog entry that focuses on the answer to that question. Rather, it is more of a "puzzlement" on the PERSON who would ask such a question.

So if someone asks you that question online, or if you read a question like that online, what would be your first reaction? I'll be honest, my first reaction was : why is this person THAT lazy?

Let me explain why my reaction was like that. If this was asked, say, 15, 20 years ago or more, then I would not have that reaction. I would try to spend time and clearly explain why aurora borealis is NOT caused by Cherenkov radiation. Now, it is not obvious why, of course, to anyone who isn't familiar with physics. So that is a perfectly valid question to ask! Nothing wrong with that.

But when asked in this day and age, one wonders why the person never googled for the answer before asking. Now, I'm not talking about the question popping up over some casual cocktail party where someone just remembered the question and decided to ask it. After all, with all the conveniences and ability to look up practically everything imaginable, there is no longer any excuse for NOT having, at least, some answers in something. It would be a different matter if someone has read something that he/she didn't understand, and want a clarification. But asking questions like "What is the mass of a photon?" or "What is quantum mechanics?" etc.. etc. that are really either very general or extremely available online is rather puzzling.

Learning is a very PERSONAL journey. It is your own self-realization and understanding. So whenever one likes it or not, one has to do one's own homework. It can't be shoveled into you. My point here is that, at least from my perspective, if I don't know something, I look it up FIRST. Typically, if it is way outside of my area of expertise, I will always encounter something that I don't quite understand. Even then, I will try to look up other resources and see if I can find something that that would explain it better. Only when that fails, I will try to seek help. In other words, I don't go around posting online the very first question that goes through my head without first trying on my own to find the answer. With all the information available on the web, there's no reason for that.

Unfortunately, with such easy access to various information, are people simply getting too lazy? It is now no longer sufficient that most of what we want to find is only a few clicks away without having to leave our computer. Those of us old enough to remember going to libraries and hunting through card catalogs to find either a book or a journal certainly would not understand such laziness. I have seen way too many instances of people, especially kids in school, whose attitude borders on some notion of ENTITLEMENT to be given the answers to any question that they may have. "I have an question, so give me the answer!". That isn't learning.

So, is aurora borealis caused by cherenkov radiation? One can easily satisfies oneself that it can't be simply via logic. Our atmosphere is bombarded by a lot of high energy charged particles, all over the earth. Yet, aurora borealis occurs predominantly at the earth's poles. If this is nothing more than cherenkov radiation, it would be common all over the world. Yet, we don't see that.

BTW, we do detect cherenkov radiation from high energy cosmic rays. That's what many of the detectors such as the Auger Observatory are doing. Clearly, no aurora borealis accompanied such detection.



Anonymous said...

I agree with you that many are, in fact, too lazy even for a simple google check on anything you might wish to look up, but also note that the signal-to-noise ratio is very poor in the land of the internets. Maybe the person was looking for clarification from an expert?

KJP said...

On the other hand, you should be careful to get your facts straight when you complain about people not looking things up. Auger looks at nitrogen fluorescence from cosmic ray showers. Other experiments, primarily looking at VHE gamma rays, are called Air Cherenkov Telescopes, and look at precisely that, including HESS, MAGIC and VERITAS.

ZapperZ said...

I DID get my facts straight!

Auger Observatory has TWO different sets of detection. One is via the fluorescence, the other is via those large water tanks that the particle goes through to create the cherenkov radiation!


I know about the fluorescence detection - I was a part of the AirFly collaboration that did the calibration on those detectors!


KJP said...

Well of course the water tanks use Cherenkov radiation, but it is very misleading in your post which starts with a discussion of the aurora. Since Auger is using fluorescence in the air, and since other Air Cherenkov experiments exist this leads to simple logical confusion regarding what you were referring to. My apologies on the fact checking statement.

Swanny said...

And if the lazy person before me had not asked the question, where, pray, would I find the answer? You can look on Wikipedia or specialist websites all you like, but I can guarantee you that Cherenkov radiation will never be mentioned in an entry on the aurora borealis, and the aurora borealis will never be mentioned in an entry on Cherenkov radiation. The only way to answer that question is to ask a subject expert, or, as in the case here, to retrace the steps of another who has done so.

Peter K. said...

Circa 10 years later: This rant about laziness and entitlement on one's personal journey of learning is the first entry that pops up in a Google search for the key words "cherenkov radiation aurora".

A.Davis said...

May 19th, 2019 another google search for "is aurora borealis caused by cherenkov" query. I came here because the result looked promising. I did find my answer here, just in an unexpected way!

You don't have to publish this comment, dear moderator. It is just interesting how everything can change and how anything can be a learning experience.

NDTyso said...

Northern Lights are Cherenkov radiation in the sense the electrons are emitting light due to them being charged beyond the speed of light in a hydrostatic atmosphere. I'm not going to bring myself to your level of blind neglect, or insult you. My only opinion is for you to revisit your education. Cheers.

ZapperZ said...

@NDTyso: I think it is you who needs to revisit your education, unless you think everyone at NASA should do the same thing as well.

You can't simply claim that it is caused by such-and-such and then IGNORE the numerous published articles and papers on this. And not only that, you fail to provide any valid arguments for such a thing.

Unlike you, I will explain why cerenkov process is not the origin of such northern lights. The index of refraction of air at STP is practically the same as vacuum (1.00029). This means that these electrons have to be moving at unbelievably close to c! And this is exacerbated by the fact that the upper atmosphere is even less dense than at sea level, meaning that the index of refraction is even closer to 1 over many decimal places! There is almost no chance of such particles generating any cerenkov radiation.

BTW, our atmosphere is continually bombarded by extremely high-speed charged particles from cosmic origin. They have been shown to be magnitudes faster than the ones coming from the sun. If cerenkov radiation is responsible for aurora borealis, then we will be seeing it all the time, and over all regions of the earth. This is not what we see.