## How a Ball Breaks a Window

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Here's a question I like to play with from time to time. I hope you physics guys can help me with it. I can place a baseball on a pane of glass suspended between two saw-horses and the glass does not break. I can then drop that ball from several meters above and whalla, the window shatters.

Now sure, it the falling ball has kinetic energy that it will impart to the glass pane whose atoms are so rigidly aligned they can't accept the energy transfer and hold shape so they break apart. But what does that mean, exactly?

Can anyone paint me a picture of this magical energy transference, and please not one full of one's, zeros and squiggles? Talking about pictures, here's what I don't get. I can take a photo of the baseball sitting on the glass and one of the baseball at the exact instant it contacts the glass and the photos are identical, and yet one will impart energy sufficient to break the glass and the other will not.

I'm interested in atomically what has happened? Have the atoms of the baseball acquired directionality in the forces that hold it, thus giving it a higher frontal energy than normal, causing a higher energy transference when it contacts the glass?

If I freeze time and walk over to both baseballs, the sitting one and the falling one and try to move them about, will the falling one feel like one of those spinning bicycle wheels you can hold between your hands and turn? Will it kick against me and try to maintain its directionality, while the other is passive to any movement? I think it might, but why? What has happened to the sub-atomic alignment of the falling baseball?

Now I do get relativism as much as a layperson can and might put a similar post to this one out there about accelerating objects. I get that through acceleration it has increased its mass (but don't really get it on an atomic level), but back to our baseball, even if it struck the glass with a zero acceleration but relative velocity, the question still stands what is different internally in baseball 1 vs baseball 2?

Thanks for indulging me, fire away.
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I think you are wondering what is it about motion that gives itself away other than the effects of motion....?
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I can take a photo of the baseball sitting on the glass and one of the baseball at the exact instant it contacts the glass and the photos are identical, and yet one will impart energy sufficient to break the glass and the other will not.

But in one, the glass is not bending, nor the ball flattening. In the other, the snapshot looks completely different. The electrostatic bonds holding the glass atoms together are being visibly stretched towards the point where they could break. Even the ball is being tested on that score. It could have been the one to shatter instead.
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Jake you are right. I guess I am wondering if there is a way to internally change the atomic energy configuration of a stationary object so that it suddenly acquires velocity or acceleration. I mean, the falling baseball is in an energy field created by gravity, but what has that energy field done to the ball to cause it to move? Has it dragged the own energy fields of the atoms in the ball assymetrically, thus giving directionality to the atoms and creating movement?
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The actual nature of motion is something that appears to have received very little attention in philosophy and science. We seem to take it for granted but it's actually quite weird!
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I guess I am wondering if there is a way to internally change the atomic energy configuration of a stationary object so that it suddenly acquires velocity or acceleration. I mean, the falling baseball is in an energy field created by gravity, but what has that energy field done to the ball to cause it to move? Has it dragged the own energy fields of the atoms in the ball assymetrically, thus giving directionality to the atoms and creating movement?

If I understand correctly, the falling ball has kinetic energy. In relation to the atoms in the glass, the energy is expressed as potential energy in the form of field mathematics. So the energy in the ball is not understood to transfer directly from the atoms of the ball to the atoms of the glass, because the fields are intermediary. So the energy of one object cannot be comprehended as transferring directly to another object.

The reason for this, I believe, has to do with the problem of conceiving of an object going from zero velocity to having some velocity in an extremely short period of time. You can see that if the object is considered to have zero velocity, then have a specific velocity, there would have to be a period of time, as the object leaves zero, when acceleration is infinite. I believe the very same problem is expressed from a different perspective in the uncertainty principle of the Fourier transform. In wave theory, the shorter the time period, the more uncertain is the frequency, so there is a time/energy uncertainty relation. In an extremely short period of time, the energy uncertainty approaches infinity.
• 2.1k
The situation is easier to understand in terms of momentum rather than kinetic energy.

The key equation is that the Impulse delivered over a period of time, which is the increase in momentum over that time, is equal to the time multiplied by the average force over that time.

Say the ball is travelling at 20 m/s and the window is 4mm thick. Then the ball takes only .004 / 20 = 0.0002 secs to pass through the space occupied by the glass. The bonds in the ball are much stronger than those in the glass, so the ball barely deviates and the glass is forced to move forward, at almost the same speed as the ball.

The mass of the glass directly in front of the ball would be around 30g. So the Impulse it has received in that 0.0002 secs is (20 - 0) * 0.030 = 0.6 Ns. Dividing by the very short time in which it was delivered - 0.0002 secs - gives an average force of 3000N, which is approximately the weight of a 300kg mass.

That force will be applied to the bonds connecting the circle of grass in front of the ball to the rest of the pane of glass. The force will be much greater than the strength of the electrostatic bonds holding the glass together, so the glass breaks.

In brief, placing a ball gently on the glass exerts a force only equal to the weight of the ball, say 5N. Throwing the ball against the glass at 20 m/s exerts s force of 3000N, which is 600 times as great.
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Thanks Andrew, that's a good explanation.
However, I want to go bit further than a Newtonian explanation. Words like impulse and momentum while providing a great working schema, do not really address what is happening fundamentally. Even the idea of energy transfer really does not say much. Atomically - interatomically or subatomically what are those energy fields doing? How have them been altered to create the movement and resultant impact force?
Maybe I should repost this so the topic is a little clearer.
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My take would be this based upon the universe being a holographic field in nature. One holographic energy field (the ball) interacts/interferes with another holographic energy field (the window) and in doing so creates a new holographic interference pattern which might be perceived as shattered glass. The ball stays interact due to the interaction patterns.

Now you don't have to repost! :) Stick with me. I'll give you some creative ideas to mull over.
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My take would be this based upon the universe being a holographic field in nature.Rich

What is a holographic energy field? Only reference seems to be to crackpottery - http://ambafrance-do.org/spirituality/24334.php
• 3.2k
lol. I thought you were just an illusion. Why the heck do my neurons keep illusioning you? Stop it! Stop it! Those silly neurons. They can get so whacky at times. Playful little imps they are. Maybe I should go to a neurologist to have a good talking to with them. Don't you think?

There subject was crackpottery want it?
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I keep telling myself, it is just an illusion, it is just an illusion. Please little neurons make it go away.

Just to be clear, I love my neurons, or is it that they love me. Anyhow it is just a bunch of crackpottery, so why bother.
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Anyhow it is just a bunch of crackpottery, so why bother.Rich

So you don't even believe in it yourself enough to try to defend it?
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I just don't know why my neurons keep creating this awful illusion. I don't even know how to handle such a situation. Do neurologists make house calls? What I would like is for this particular illusion to be done in Technicolor. Doable?
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Remember that the maths was developed to deal with idealised point objects. So the Zeno-style paradox of jumping to the first next point to get moving is an artefact of that maths.
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Sure Rich, I get it. The holographic field is a good way of visualising the atomic framework of objects and introduces a wave property that is otherwise hard to imagine.
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Exactly.

Now if you think of the mind using the brain a to project a reconstructive beam that is illuminating the interference pattern, then you have a a possible way of imagining how it all might be working.
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Does the ball still break the glass if no one is around to observe? (I am trying to imagine things as you are describing them.)
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You crack me up Rich. What the hell is a reconstructive beam?
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A reconstructive bean is the laser beam that is used to illuminate the holographic image. The image is out there and the brain is the tool that the mind uses to illuminate it. Nothing is going on in the brain.
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So vision is active, not passive? We blast out a huge quantity of energy to illuminate the image? How do we then perceive it once it's illuminated? That's a bridge too far for me.
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Isn't this the same thing as Zeno's paradoxes of motion?
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The mind sees it as light illuminates it. Light and mind are inextricably related. If you wish to understand nature, follow the light.

There are some excellent (but slow moving) videos on this subject on YouTube created by Stephen Robbins. If you are interested, you may be able to follow it, but a background on Bergson helps a lot. It depends upon how interested you are in this line of inquiry.

The main point is that the brain is like a TV set, it reconstructs but it's not the origin not is it the storage media. Robbins explains why.
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Hi Jess, beats me. What are Zeno's paradoxes of motion?
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OK, thanks Rich, I'll check it out.
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If it is overload, just bookmark it for the future. You get the idea and that's enough just to keep in mind as you explore the nature of the mind.
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They are interesting paradoxes which Zeno used to demonstrate that space and duration (time) must be considered indivisible. Read the paradoxes, because no doubt you have been taught that space and time are divisible and will be confused by them, and then read Bergson's solution. The paradox disappears if one considers all motion and duration continuous. Symbolic mathematics creates the paradoxes because symbolics cannot reflect a continuous reality.
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What are Zeno's paradoxes of motion?

hi, I think the arrow one might be closest to your OP (in that it discusses a specific moving object).
https://plato.stanford.edu/entries/paradox-zeno/#Arr What I meant by that is visualising time at instants. Being able to switch the balls. I'm not sure if being able to divide motion in such a way is possible, but the thought experiments exist.
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Thanks JupiterJess and Rich, I've read through the paradoxes. They would make a great topic for another debate. The arrow one you pointed out does have a similar framework to what I am trying to say, but what I am saying is also different.

If we took the arrow in flight analogy. I do want to freeze frame it, just like the paradox. But I want to swap it out for an arrow that is not in flight:One that I pull out of my quiver. When I release time again, the swapped out arrow will drop lifelessly to the ground while the in flight arrow will continue its flight.

As both arrows are identical in appearance, it is my contention that the difference between the two arrows must have to do with a difference in the energy fields of the atoms within the arrow. Could it be that an asymmetry in the energy field of an atom (pulling all the energy fields in a singular direction like a magnet) is creating the motion.

If we can accept this assumption then we can elaborate on it further to say, an initial change in the direction of the energy field creates acceleration. The restoration of the energy field thereafter maintains a velocity at the point of release, a further tug will cause further acceleration.

That being said, I can envisage a futuristic programmer typing a value and direction of the energy field into an object and causing it to spontaneously leap into a state of acceleration.
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