Frequently Asked Questions

Abstract

Here I have listed some questions that I am frequently asked together with the answers I usually give. The site is subject to permanent update.

Science
Computers
Opinion
- What political party do you like best?
- Is the FPÖ the liberal party in Austria?
Private
Odds and Ends

Science

Why is the standard deviation of my experiment's data so big?

In most cases I've seen this was a problem of wrong data analysis rather than poor experimental work. You also shouldn't forget that the standard deviation has no useful meaning for a set of less than three data points. If you think the problem is within the data, try running an outlier test. Never attempt to eliminate data points just to reduce the standard deviation. It will make your data even worse! (And it's cheating.)

Please don't misinterpret the ratio standard deviation / mean value. If you measure a quantity that's true value is zero, your measurements might be very precise but the aforementioned ratio will still be very large. A general statement can hardly be made on this. Usually you expect a small value to have a small standard deviation but it will be necessary to determine whether the zero point was chosen arbitrarily. For example, measuring the melting point of benzene as (3.0±2.0)° C is just as good (or bad) as measuring it as (276.2±2.0) K. The zero point of the Celsius scale is arbitrary and has no physical meaning. On the other hand, measuring the thickness of a sheet of paper as (0.2±0.5) mm is an almost useless result while measuring the focal length of a lens as (47.3±0.5) mm might be satisfactory for many applications. Here, the zero point has a physical justification.

What units do I have to use for this formula?

Any units you like as long as you stay consistent. If you put in consistent units but the result doesn't come out right then the formula is wrong.

Einstein's formula E = m c² explains why a nuclear reaction yields so much energy, right?

Well, as right as it explains why dropping a weight releases the amount of energy it does. This famous equation says that there is equivalence between mass and energy. But this on its own doesn't explain where either of them came from. The reason people think about nuclear reactions when hearing the formula is probably that the energy released in a nuclear reaction is so huge that the mass defect can be directly measured. But the equivalence of mass and energy is in no way unique to nuclear reactions.

How do I express 1.4 in a number with three significant digits?

If you don't want to cheat: not at all. There is not a single reason to assume that 1.4 = 1.40.

Proof:

Type sqrt(2) in your pocket calculator.
Count the number of digits it displays.
Write down the first two significant digits on a sheet of paper.
Compare the number on your sheet with the number on the display. Do they match within the given digits?
Now append Zeros to that number to reach the number of digits you've counted before.
Compare the number on your sheet with the number on the display. Do they match within the given digits?

1.4 = 1.4±0.05 while 1.40 = 1.40±0.005. This is not the same and you can't transform the first into the second without redetermining the value with greater precision by computation or measurement.

Why shouldn't I write the units of my plot's axes into square brackets like in ‘m [kg]’?

Because the [·] operator has a clear meaning. [U] is to be read as “the unit of the quantity U”. Thus it is correct to write [m] = kg to express “the quantity mass is expressed in the unit kilogram”. However, on the plot or in your table head, you'd like to say something different. What you want to say is: “I have just written some numbers here but please read the number x as U = x·u where U is the physical quantity I want to express and u is some appropriate unit.” The most straight forward way to express this in mathematical language is to divide off the unit. So for an axis label or table head you may write m / kg. It is convenient to reserve the ‘/’ for this division and use negative exponents inside the unit if inverse units are needed. I_λ / W m^–2 nm^–1 will be understood as I_λ / (W / (m² nm)) but it looks much nicer.

A proper example of a graph and a table are given below.

It follows a preformatted block of meaningless ASCII characters arranged to show a graph and a table. A screenreader will not reproduce this information in a useful way. Skip it.

 t / s   6.0 +-----+-----+-----+-----+-----+-----+      +----------+----------+
             |               x              x    |      |  m / kg  |  t / s   |
             |                                   |      +----------+----------+
         4.0 +             x   x                 +      |  0.51    |  1.7     |
             |                                   |      |  0.82    |  2.9     |
             |         x                         |      |  1.23    |  3.9     |
         2.0 +                                   +      |  1.29    |  5.5     |
             |     x                             |      |  1.52    |  4.1     |
             |                                   |      |  2.60    |  4.3     |
         0.0 +-----+-----+-----+-----+-----+-----+      +----------+----------+
             0.0   0.5   1.0   1.5   2.0   2.5   3.0

                                            m / kg

Computers

Why do you run GNU/Linux? Is it really that much better?

Well, it is much better than the popular proprietary operating systems. But that's not the only reason for me to use it.

Unlike proprietary operating systems like MS Windows or Mac OS X a free operating system gives me as the user full control over my computer rather than initially giving full control to the company that sells the operating system and then depending on their generosity to partially hand it back to me. I want to know what my computer is doing and I want to be sure it doesn't do things without me asking for them.

Is it hard to switch to GNU/Linux?

Not really. If you are a moderately skilled computer user you'll quickly figure out how to use it and most things are very well documented and you'll find a huge helpful community to ask.

It might not support the full functionality of all your hardware in the way your former proprietary operating system did. This can be annoying but please don't blame the distributors of your GNU/Linux distribution for this. They try their best to support any hardware as good as possible but many vendors don't cooperate and make a secret of how their products work. This makes it almost impossible to write free drivers for such devices. The best solution is not to buy such hardware.

Most people actually don't spend hours sitting in front of their computer starring at the bare operating system but use some other software that runs on it. You've probably already been using some cool programs like Firefox, Thunderbird, Inkscape or the VLC media player that are free software and have their origin in the GNU/Linux world. You will be able to keep on using them and a whole lot of more cool software. Switching the operating system also means loosing support for some software. This can become an issue if you need exactly one tool to collaborate with other people. If this is the case you could talk to your co-workers about switching to an open standard that won't tie your group to the products of a specific company. This will enable all of you to work with the software they like best and still allow for fruitful cooperation. Also think of the possibility that the company that sells you your program bankrots. If your files use an open standard you will always be able to recover and continue your work.

What was that file attached to your e-mail good for?

It is a PGP signature. You can read more about it on Wikipedia. Using this file and the appropriate software, you can verify that the e-mail was sent by me and nobody else.

Can I have a `.doc`, `.docx`, `.ppt` or `.pptx` version of your document?

No, because I don't have on either. But in most cases you can get the LaTeX source if that helps you.

What programming language should I start with?

This is a difficult question. If you can afford it, I'd recommend not to start with the language that seems most useful to you (maybe because your company / school widely uses it) but with one that is clear and consequent. Pascal was designed for exactly that purpose.

Tough I love Python, I don't think it is a good idea to start with a language that doesn't enforce explicit typing. (Also see the xkcd comic #409.) I though think that consequent object orientation from the very beginning is a good thing.

In any case: Once you've learned how to code, you'll find it very easy to learn another language. If you have the chance you should attend a class or read a book for an introduction to Informatics. This will help you a lot to understand what is going on inside your computer and why you have to code some things that way and not the other. I can't recommend you any favorite book of mine.

Will you help me with my LaTeX problem?

Sure.

Opinion

What political party do you like best?

Political parties are very important for a democracy to work. However, they are (at best) just representatives of an idea, rather than an idea themselves. A party has to address many demands and it is not an easy task to do so. The image of a party is heavily determined by the faces that constitute it. Those faces have nothing to do with the values behind the party's engagement. I do support a specific party – the one I agree most with. But when discussing about politics, which is a very important thing to do, I prefer talking about ideas rather than faces.

Is the FPÖ the liberal party in Austria?

No, the FPÖ do uses some liberal terminology from time to time (as in its name: “freedom party”) but by no definition it can qualify as a liberal power. Especially, it can't be seen as an equivalent to the German FDP which indeed is a liberal power. The FPÖ is heavily on the right side and can't be recommended by any clear thinking individual. There is no established liberal party in Austria. The JuLis (young liberals of Austria) have nothing to do with the FPÖ but are a self sufficient – though tiny – party of their own.

Private

How is your surname spelled?

Like you've spelled it when typing the URL for this website. The letter ‘g’ does not occur in it.

Are you from Australia?

No, I'm from Austria. We have no Kangaroos there. The only thing that is from Australia is my hat.

Have you seen popular movie?

No.

Why are you wearing a hat?

I'm not really a not-wearing-a-hat person. (Disclaimer: I never did or will do the chin-up bar thing!)

What does the ribbon on your hat stand for?

The ribbon (depicting a broken measuring tape) is an initiative of the city of Vienna. Inspired by the Red Ribbon (emphasizing solidarity for people living with HIV/AIDS) it is a symbol to express awareness of the danger that lurks for – especially but not exclusively – young women living in a society that makes them feel that they have to meet a certain ideal of a “perfect body” thus leading to dissatisfaction, psychiatric diseases, anorexia or even life threatening situations if they can't.

The initiators of the campaign spot the slogan “No BODY is perfect”, adding “…nor it has to be”. I slightly disagree on that slogan because it still implies that there is something like a perfect body. But what should that be? In the field of engineering a perfect body could be a sphere (or whatever mathematically well-defined object) with absolutely no deviation from it's theoretical form. The quartz gyroscopes in the Gravity Probe B spacecraft presumably were almost perfect bodies. But such a definition doesn't make any sense for a human body. Instead, speaking of a perfect human body anyone should try to approximate as much as possible is just as ridiculous as it would be to speak of the “perfect artwork” artists should try to copy. What a frustrating point of view! Instead of telling people: “You don't look perfect but I don't mind.” I rather prefer to tell them: “You look the way you do and it is your chance to convince us that this is awesome.”. Anyhow, I like wearing the ribbon because its main feature is to provoke discussions which is just what the subject needs.

How are you?

I hate asking this question to make smalltalk. If we know well and talk about private things we're gonna talk about how we feel anyhow. And if we don't know well I usually don't want you to know how I feel nor will I feel legitimated to know how you feel.

Addendum: It is certainly okay to use “How are you?” as an alias for “I know you have been ill recently but now I am pleased to see you're up again. Are you doing well again or do you still feel weak?” or things like that.

sneeze

Well, this is not a question. But if you sneeze, I usually won't say “Gesundheit!” as it is common in German speaking countries. I guess that you are embarrassed enough and I can't see a single good reason for further emphasizing the fact that you had to sneeze. I might though offer you a handkerchief if it seems appropriate.

Hi!

Many people say “hi” to me every day and most of the time I say “hi” as well and walk my way off assuming that we only know very briefly. Sorry, it's not about you but I'm simply very bad at remembering people's names or faces and if I would worry every time somebody greets me without me recognizing the person, I'd be worried all night and day.

If you're interested in conversation and start with a “Hi, I'm your name. We know each other from wherever we might know us from.” you can have a huge hug if you want.

What does the m_γ on many of your documents stand for?

If you read it out loud, ‘m_γ’ sounds a little like “M.Klammler”. Furthermore, it may stand for the photon's mass – a tribute to the Gravity Probe A experiment that showed that the photon has indeed a relativistic mass and that this mass interacts with the gravitational field.