In the first Mishna in Sucah the Rav from Bartenura brings the Gemara which says if the sun and branches are even on top then the shadow is more on the bottom so it is kosher. כדאמרי אינשי כזוזא מלעילא כאסתירא לתתא
If you are in a desert and you are trying to spot a fighter plane in the sky, the way to do it is to look for its shadow. The reason is the shadow is always much larger than the plane itself. What is puzzling about this is the fact that the Gemara seems to consider the shadow on the floor to be the determining factor as to whether the Sucah is kosher or not. It says that being equal is OK because on the bottom the shadow is more.
According to this reasoning then the top סכך (branches) could be much less than the shadow because of the bottom the shadow of the סכך (branches) will be expanded. That means this Gemara is a puzzle because it says on top the סכך (branches) and sun need to be equal.
[I had a small copy of the Mishna [on Moed] I carried around with me for years so that I would not forget my learning as I was being thrown out from every yeshiva I stepped foot in. For some reason I was not just unpopular, but literally thrown out (sometimes physically, sometimes it was from the sound of people saying I was there for their hot-dogs and other times I was accused of much more horrendous things. But the main thing seemed to be the intent to get rid of me more than the accuracy of the accusations.) from every yeshiva I walked into. Maybe I am not worthy to learn Torah? And if I happened to be married they made sure to correct that situation as fast as they could also. So for me to hold on to Torah was hard,--and still is.
I still have great problems when it comes to keeping Torah, internal and external. This tells you part of the reason that I think Torah with Derech Eretz . Torah with work = that is a regular job and not to use Torah to make money. That is a better approach than Torah all day. It is mainly because the Torah all day approach seems to have the law of limited returns working against it. It is like drinking water. The Torah is after all compared to water. There is a certain point one can get to that drinking more than his stomach can hold can be dangerous.
Just to be clear yeshivas should throw out people as many as possible, But not people that are there to learn Torah for its own sake. There is nothing wrong with throwing out trouble makers. But trouble makers are not usually whom they throw out. Just the opposite. It is usually the sincere people that get thrown out.
But in any case if yeshivas existed in order to learn Torah, then this would be inexplicable. But if they exist in order to use Torah as a business or as a way to get out of army service, then this makes a lot of sense. They don't want people that learn it for free or for its own sake. The solution to this is not easy. But the general direction I would take would be to separate Torah from Money. Torah should not be paying profession because when it is that attracts the flies.
In any case in that copy of the Mishna I wrote a possible solution to this dilemma. My solution is the fact that there is no exact mathematical solution to the problem of diffraction. I mean to say that every shadow has one area that is dark, and another area that is half dark and half light. That area can extend to infinity. So when you say the shadow on the bottom has to be more than the light, it is not clear what that means. The area of the shadow can be infinite. Therefore the Gemara held only when the shadow and סכך (branches) on top are equal is it kosher.
You could perhaps also suggest to take the dark area as the key factor. You could call it 100% shade. And then when that gets to be 49% light call it not shade. I don't know why the Talmud did not choose this approach? Besides I wonder if we could go by just the dark area alone? But again the Talmud does not seem to want to focus on the dark area either. Instead it chooses this path where on top they are even and on the bottom the dark area is larger. Maybe a physicist could come up with an explanation of what the Talmud is saying here and why it choose this path?
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In the first משנה in סוכה the רב from ברטנורה brings the גמרא which says if the סכך and צל are even on top then the צל is more on the bottom so it is kosher. כדאמרי אינשי כזוזא מלעילא כאסתירא מלבר
If you are in a desert and you are trying to spot a fighter plane in the sky, the way to do it is to look for its shadow. The reason is the צל is always much larger than the plane itself. What is puzzling about this is the fact that the גמרא seems to consider the צל on the floor to be the determining factor as to whether the סוכה is kosher or not. It says that being equal is OK because on the bottom the צל is more.
According to this reasoning then the top סכך could be much less than the shadow because of the bottom the shadow of the סכך will be expanded. That means this גמרא is a puzzle because it says on top the סכך and shadow need to be equal.
In any case in that copy of the משנה I wrote a possible solution to this dilemma. My solution is the fact that there is no exact mathematical solution to the problem of diffraction. I mean to say that every shadow has one area that is dark and another area that is half dark and half light. That area can extend to infinity. So when you say the shadow on the bottom has to be more than the light it is not clear what that means. The area of the shadow can be infinite. Therefore the Gemara held only when the shadow and סכך on top are equal is it kosher.
You could perhaps also suggest to take the dark area as the key factor. You could call it 100% shade. And then when that gets to be 49% light call it not shade.
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במשנה הראשונה בסוכה הגמרא אומרת שאם הסכך והצל שווים על גבי הסוכה אז הצל הוא יותר בתחתית כך שהיא כשרה, כדאמרי אינשי כזוזא מלעילא כאסתירא מלבר. אם אתה במדבר ואתה מנסה לזהות מטוס קרב בשמיים, הדרך לעשות את זה היא לחפש צלה. הסיבה לכך היא הצל הוא תמיד הרבה יותר גדול מהמטוס עצמו. התמוה על זה הוא העובדה שנראה שהגמרא שוקלת צל על הרצפה כדי להיות הגורם המכריע בשאלה האם הסוכה כשרה או לא. זה אומר שלהיות שהם שווים למעלה הוא בסדר כי בתחתית הצל הוא יותר. על פי היגיון זה אז סככת העליון יכולה להיות הרבה פחותה מהצל בגלל שבתחתית הצל של הסכך יורחב. זה אומר גמרא זו היא חידה כי זה אומר על גבי סכך והצל צריך להיות שווה. הפתרון שלי הוא העובדה שאין פתרון מתמטי מדויק לבעיה של עקיפה (דיפרקציה). אני מתכוון לומר שלכל צל תחום אחד שהוא כהה ואזור אחר שהוא חצי אור וחצי כהה. האזור הכהה יכול להאריך עד אינסוף. אז כשאתה אומר הצל בתחתית צריך להיות יותר מןמהאור, לא ברור מה זה אומר. האזור של הצל יכול להיות אינסופי. לכן הגמרא מחזיקה שרק כאשר הצל וסכך על גבי סוכה שווים זה כשר. אתה אולי יכול גם להציע לקחת את האזור הכהה כגורם מפתח. אפשר לקרוא לזה מאה אחוז כהה ואז כשזה הופך להיות ארבעים ותשעה אחוזים לקרא לזה לא צל. אבל הגמרא לא בחרה בדרך הזו.