DADA-601 Lessons

Now that we have covered the theory of non-verbal spellcasting, I expect each of you to practice this skill with the same determination you practiced casting spells without their wand movements. There will be no formal assignments to practice this skill, but it will be expected that you can non-verbally cast at least a few spells by the time you sit your N.E.W.T.s. Today, we will be moving forward from strict theory and focusing on spells, though there will certainly be theory involved

The Shielding Charm
This lesson will focus on the Shielding Charm, some theoretical information that will make casting the spell more effective for you, and practical applications of the Shielding Charm (and also impractical uses). There are many ways that the Shielding Charm can be modified, which you will explore in your essay for this lesson. Have no fear, all of the spells I will ask you to work with have been covered in previous courses, so you should be well versed in each of them. If not, I suggest you brush up on them.

To be blunt, the Shielding Charm is one of the most common and useful defensive spells you will learn. When cast properly, it will deflect all spells that are cast in your direction. There are two exceptions to this. First, the Shielding Charm will never deflect an Unforgivable Curse. These curses, which you should at least be minimally aware of, are simply too powerful. They require too much effort to cast for any opposed force to be able to deflect them. The second exception to this is that the Shielding Charm will not deflect spells that are cast with more willpower applied than you put into it. To give you an example, if you are in a combat situation where your opponent casts the Impediment Jinx at you, a viable option is to cast the Shielding Charm in defense. However, if you opponent has put more willpower into their Impediment Jinx than you have put into your Shielding Charm, the Impediment Jinx will shatter your Shielding Charm and you will still be affected by the difference in energy applied. There is a third possibility: both spells are powered with an equal amount of willpower. In this instance, the shield created would be broken, but would also effectively stop the spell.

Let us take a moment to think about what this means. When we talk about application of willpower, what we are actually referring to is application of magical energy. Every magical individual has an infinite amount of magical energy at their disposal, but if they use too much of this magical energy at one time, they suffer from magical exhaustion. Every spell you cast utilizes a certain amount of magical energy. Static spells will only have as much willpower as you initially put into them, while dynamic spells are able to have more willpower pushed into them if needed, since the spell is extended across the duration of your held concentration. The Shielding Charm is a dynamic spell and can, in theory, have more willpower pushed into it. But why use more willpower if you don’t know how much you will need?

This is one of the challenges that is associated with using the Shielding Charm, and why it has been saved for your N.E.W.T. level work. The most important part of casting this spell is being able to guess how much willpower your opponent will put into a spell. If you put too much energy into your shield and you will block the spell, but waste magical energy that you could use to go on the offensive. If you put too little willpower into your shield, you will weaken the spell targetting you, but will still be affected by it to some degree. The degree by which you are affected will depend entirely on the spell that gets through. Usually, though, it is simply a weakened effect: the Knockback Jinx will push you with less force, the Impediment Jinx will be less effective depending on the chosen effect, and the Disarming Charm will be easier to resist.

If this all sounds very theoretical and mathematical in some senses, that’s because it is. However, we will not be delving into the mathematics of magical energy and such in this course. While knowing this can be helpful in some circumstances, there is no practical application of it since you cannot accurately quantify the willpower you put in, which would be a required component of the calculation. Suffice to say that there is a theoretical formula which, if magical theorists ever find a way to quantify willpower, could be used to determine the amount of magical energy used when casting a spell.

Force Fields
While we will not be exploring the specifics of the spellcasting components - I expect you all to be more than capable of determining concentration and willpower on your own, though I will provide you with the incantation and movement at the end of the lesson -  we will be covering the type of thing you are expected to be envisioning when you cast this spell. The science we will be going into, the science of force fields, is slightly beyond my areas of expertise, and so I have requested the assistance of someone far more knowledgeable than I. Please give a warm welcome to Professor Adalbert Scantlebury. He is a wizard who chose to forgo the magical world in favor of Muggle physics, and is currently a professor of physics in the United States. I must warn you that he is a bit eccentric. I have run into him on more than one occasion for violations of the International Statute of Secrecy. However, he is well-versed in the science of magic - which happens to be the title of one of his books - and will be more than capable of assisting in today’s lesson. Professor Scantlebury, the floor is yours.

Hello, hello, students! It’s great to be here, thanks for having me ole Jerry, ole pal. So I hear you all are working on shielding, am I right? Shields are immensely useful and come in many different shapes and sizes and forms and I’ve gotta say, magical ones are by far the most intriguing. It’s not hard like armor or thick like a wall, but will stop some of the most deadly of attacks. How might it do this? By force, of course! One might even call it...a force field? Yes! Force fields have been a subject in fascination in both the magical and No-maj worlds for years and it’s clear to see why. But how do they work? Jerry here has tasked me with teaching you all this today so buckle up! It’s gonna be quite the ride!

I suppose the best place to start is the beginning. In order to understand a force field, you must first understand a force. In simple terms, a force is either a push or a pull. It is a strength or energy that intends to move, stop, deform, or change the direction of whatever it is acting upon. A field, in this context, is a two-dimensional plane of reference, which you can imagine as a sheet or plate. Therefore, a force field is a sheet of energy that intends to move, stop, deform, or change the direction of whatever happens to interact with it. What makes a force field different from any regular metal shield, you may ask? Excellent question! The key distinction is in the term “energy.” You see, your typical knight in shining armor has a shield that is composed of mass, the “stuff” that makes up all the items you can see and feel around you.  The shield created by your Shielding Charm, however, is composed purely of energy.

Next question: what kind of forces exist and which are best to form a shield? While there are many different kinds of forces, from gravitational, to frictional, to resistance, there are three in particular that make for the best shields: electrical, magnetic, and magical. All three of these forces are action-at-a-distance forces, meaning that they don’t need to be physically touching something to have an effect on it. This is the first key criteria to a force being utilized as a force field, as an energy barrier is unable to physically touch anything. The second key criteria is that these forces are all polar, meaning they have the ability to both attract and repel, the latter being necessary to deflect an incoming attack.

While No-majs, or Muggles as you all call them, have been doing research into electromagnetic force fields for years, their goals have been slightly different from those you have here in Defense Against the Dark Arts. Their research has been aimed primarily at space travel and engineering a barrier to protect their space crafts from radiation and cosmic rays. Others are trying to generate a triggered force field that would protect a vehicle from shock waves, fast moving waves that follow a blast of some sort and that are characterized by an abrupt change in temperature that can do quite a bit of damage to your average automobile. They do this by creating shields of charged air particles, called plasma, which repel and deflect the charged, high energy particles of radiation.

I could go on all day on how these force fields are produced and maintained, but that won’t help you stave off a magical opponent, which is what we’re all here for! So the No-Majs use charged particles to protect against charged particles, meaning logic would lead you to say that magic particles would protect against magic particles! ... If magic had particles, that is ... But right you would be! The Shielding Charm creates a sheet of magical power that repels similar magical power that approaches it.  While magic is not charged positive or negative like a proton or electron, or polarized like a magnet, it is intelligent and can be programmed, in a way, by the way a spell is created and by your very own concentration, to reject all forms of magic that is not itself.

And that, my fine fellow friends, is force fields! I will now pass you back into the magical hands of Mister Jerry Penrose.

Conclusion
Thank you for that, Professor Scantlebury. I am sure the students found it enlightening and beneficial to their education and ability to satisfactorily perform the spell we have covered today, though we could have done without the informalities.

Before I let you all go to your assignment, I must give you the last pieces of information you will need in order to cast the Shielding Charm. The incantation is “Protego” (pro-TAY-go) and the wand movement is to slash your wand in an upward direction. As previously mentioned, I will leave it up to you to determine the amount of willpower and concentration needed for you to cast the spell, as I will with all spells we cover from here out.

And with that, I will leave you to your assignment. At this point, I know many of you may be wondering why I have not be administering quizzes as I have done in the past. To be frank, it is because it is difficult to find good “quizzable” information for you from these lessons. We have delved deep into theory and, as such, the concepts I expect you to grapple with go far beyond the surface level. You are now at N.E.W.T. level and should be able to handle theory more directly than a surface level quiz. However, I will endeavor to put together an adequate midterm and final examination for you. Off you go, you have some considerations to make.

Original lesson written by Professor Jericho Penrose