I think, Physics & Realism in Minecraft can help the game very well. It should be a mod where every item has a certain amount of weight like 1 dirt block = .1 lbs A player can only carry so much weight and can add more weight with backpacks such as, a player with no backpack can handle 50 lbs. Leather backpacks can handle 25 lbs more so a player can handle 75 lbs. Here is some slot ideas for backpacks

Diamond: 250+

Gold:150+

Iron:75+

Leather:25+

For example, a Stone block can be .5 lbs so if you have a stack of Stone, it would be 32 lbs.

Some other physics I believe that should be implemented into Minecraft is:

If hit by knockback and hit a wall, you should take damage like from falling off a cliff and hitting the ground.

New shade patchers should be added too even though the whole shade files were re-coded, they are worse than before.

That is all, thank you for your time