What she means is to relax your hands and feel the gravity, and play by letting your fingers "drop" on the piano with the use of it's mass and the gravity we have on earth
The gravity isn't just for fun, it has a function
. By letting your fingers drop using the gravity makes piano playing easier and more relaxed.
You can read this:
Just a few important sections:
The Chord Attack
Let's return to the (LH) CGEG quadruplet. If you practice it slowly and then gradually speed it up (HS), you will hit a "speed wall", a speed beyond which everything breaks down and stress builds up. The way to break this speed wall is to play the quadruplet as a single chord (CEG). You have gone from slow speed to infinite speed! This is called a chord attack. Now you only have to learn to slow down, which is easier than speeding up because there is no speed wall when you are slowing down. But -- how do you slow down?
First play the chord and bounce the hand up and down at the frequency at which the quadruplet should be played (say, between one and two times a second); it should be easier when played as a chord, but this may not be simple if it is your first time. Note that the fingers are now positioned exactly correctly for fast playing. Try varying the bounce frequency up and down (even beyond the required speed!), noting how to alter the wrist, arm, fingers, etc., positions and motions as you go through the different speeds. If you feel fatigue after a while, then you are either doing something wrong, or else you have not yet acquired the technique of bouncing the chords. You will need to practice it until you can do that without tiring because if you can't do it for a chord, you will never do it for quadruplets. In other words, you have just identified a weakness in the technique that needs to be remedied before you can progress to the next stage.
Play the chord with the most economical motions you can think of. Keep the fingers close to or on the keys as you increase speed. Get your whole body involved; shoulders, upper and lower arms, wrist. The sensation is to play from your shoulders and arms, not your fingertips. When you can play this softly, relaxed, fast, and without any feeling of fatigue, you know that you have made progress. Make sure that you are playing perfect chords (all notes landing at the same time) because, without this kind of sensitivity, you will not have the accuracy required to play fast. It is important to practice the slow bounce because that is when you can work on the accuracy. Accuracy improves faster at the slower speeds. However, it is absolutely essential that you get up to fast speeds (if only briefly) before slowing down. When you slow down, try to maintain the same motions that were required at high speed, because that is what you need to ultimately practice. If you think that this is the end of this simple chord business, you are in for a surprise -- this is only the beginning; read on!
Gravity Drop, Chord Practice, and Relaxation
Practicing to play accurate chords is the first step in applying the chord attack. Let's practice the above CEG chord. The arm weight method is the best way to achieve accuracy and relaxation; this approach has been adequately treated in the referenced books (Fink, Sandor) and therefore will be discussed only briefly here. Place your fingers on the keys and position them correctly. Relax your arm (the whole body, actually), keep your wrist flexible, lift the hand from 5 to 20 cm above the keys (the shorter distance in the beginning), and just let gravity drop your hand. Let the hand and fingers drop as a unit, do not move the fingers. Relax the hands completely during the drop, then "set" your fingers and wrist at the time of impact with the keys and let the wrist flex slightly to take the shock of landing and to depress the keys. By letting gravity lower your hand, you are referencing your strength or sensitivity to a very constant force.
It may seem unbelievable at first, but an under-weight 6-year-old and a gargantuan sumo wrestler dropping their hands from the same height will produce sound of the same loudness. This happens because the speed of gravitational fall is independent of mass and the hammer goes into free flight as soon as the knuckle leaves the jack (the last few millimeters before hitting the strings). Physics students will recognize that in the elastic limit (billiard ball collision), kinetic energy is conserved and the above statements do not hold. In such an elastic collision, the piano key would fly off the fingertip at high velocity, somewhat like when playing staccato. But here, because the fingers are relaxed and the fingertips are soft (inelastic collision), kinetic energy is not conserved and the small mass (piano key) can stay with the large mass (finger-hand-arm), resulting in a controlled keydrop. Therefore, the above statements hold as long as the piano is properly regulated and the effective mass for the key drop is much smaller than the mass of the 6-year-old's finger-hand-arm. Stiffening the hand at impact ensures that the entire arm weight transfers to the key drop. Obviously, it is not possible to produce the full sound of the gravity drop if you do not stiffen the hand at impact. You must take care not to add force during this stiffening; therefore, it takes practice to be able to produce a pure gravity drop and this becomes more difficult with increasing height of the drop. Not adding this extra force is a more difficult task for the sumo wrestler because he needs such a large force to stop the momentum of his arm. The best criteria for the proper stiffening force are the loudness and tone of the sound.
Strictly speaking, the sumo wrestler will make a slightly louder sound because of momentum conservation, but the difference will be quite small, in spite of the fact that his arm may be 20 times heavier. Another surprise is that, once properly taught, the gravity drop may produce the loudest sound that this youngster has ever played (for a high drop), and is an excellent way to teach youngsters how to play firmly. Start with short drops for small youngsters because in the beginning, a truly free drop can be painful if the height is too high. For a successful gravity drop, especially for youngsters, it is important to teach them to make-believe that there is no piano and the hand should feel like it is falling through the keyboard (but is stopped by it). Otherwise, many youngsters will subconsciously lift the hand as it lands on the piano. In other words, the gravity drop is a constant acceleration and the hand is accelerating, even during the key drop. At the end, the hand is resting on the keys with its own weight -- this action is what produces pleasant, deep, "tone". Note that it is important for the key drop to accelerate all the way down - see section III.1 on producing good tone.
The well-known Steinway "accelerated action" works because it adds acceleration to the hammer motion by use of a rounded support under the center key bushing. This causes the pivot point to move forward with keydrop thus shortening the front side of the key and lengthening the back side and thereby causing the capstan to accelerate for a constant keydrop. This illustrates the importance piano designers place on accelerating the keydrop, and the arm weight method ensures that we take full advantage of gravitational acceleration to control the tone. The effectiveness of the "accelerated action" is controversial because there are excellent pianos without this feature. Obviously, it is more important for the pianist to control this acceleration.
The finger must be "set" at the moment of impact so as to depress the key and decelerate the fall. This requires a brief application of force to the finger. As soon as the key reaches the bottom of the keydrop, remove this force and relax completely so that you can feel gravity pulling the arm down. Rest the hand on the key with only this gravitational force keeping the key down. What you have just accomplished is to depress the key with the least possible effort; this is the essence of relaxation.
Beginning students will play chords with too many unnecessary forces that can not be accurately controlled. The use of gravity to lower the hand allows you to eliminate all forces or tenseness in the hand that are the causes of certain fingers landing before the others. It might seem like a curious coincidence that the force of gravity is just the right force for playing the piano. This is no coincidence. Humans evolved under the influence of gravity. Our strengths for walking, lifting, etc., evolved to match gravity exactly. The piano, of course, was built to match those strengths. Remember: the amount of force you need to play the chord is roughly equal to that supplied by gravity -- don't bang those chords or tense the hands -- a lot of things will start to go out of control! For beginners or those who have developed a habit of tensing the hands to play chords, it is a good idea to practice the gravity drop for several weeks, or even months, a little bit every time you practice. And of course, it must be incorporated into the everyday practicing and playing. What this means is that when you are truly relaxed, you can actually feel the effect of gravity on your hands as you are playing. Some teachers will emphasize relaxation to the point of neglecting everything else until "total" relaxation is achieved; that may be going too far overboard -- being able to feel gravity is a necessary and sufficient criterion for relaxation.
The gravity drop also eliminates the need for momentum balance (see section IV.6). When the hand plays the piano, the downward momentum of the key is supplied by the momentum of the hand. This downward momentum must be compensated by the rest of the human playing mechanism which must provide an upward momentum if the gravity drop is not utilized. Although we all accomplish this without even thinking, it is in fact quite a complex feat. In the gravity drop method, this momentum is supplied by gravity, so that the piano is played with the absolute minimum action by the human playing mechanism. In this way, the gravity drop enables us to relax all the unnecessary muscles and to concentrate only on those that are needed to control the chord.
Gravity drop is therefore much more than just a method to practice chords. More importantly, the gravity drop is a method to practice relaxation. Once this relaxed state is achieved, it must become a permanent, integral part of your piano playing. The guiding principle in the arm weight method is relaxation. In addition to the gravity drop, it is important to learn to feel the effect of gravity as we play. We will treat relaxation in more detail below.
Finally, chord playing is an important component of piano technique. As such, it must be developed gradually in concert with your general skill level. There is no faster way of doing that than the use of the parallel sets described below. Also, see section III.7 for more details; section III.7e gives additional instructions on how to practice playing even chords when the gravity drop does not solve the problem.
I hope that's enough