Minecraft launcher won't download?

I try to open mine craft and it goes through some loading stuff and ends with this. I don't have avast or avg just the default firewall. I have updated java, and redownloaded minecraft. What now?

{Downloading: https://s3.amazonaws.com/....pack.lzma" class='ext_link'>https://s3.amazonaws.com/....pack.lzma (try 9/10)
Exception: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorExceptio… PKIX path building failed: sun.security.provider.certpath.SunCertPa… Unable to find valid certification path to requested target
Recognized exception: the likely cause is a set of broken/missing root-certificates. Check your java install and perhaps reinstall it.
Downloading: https://s3.amazonaws.com/Minecraft.Download/launcher/launcher.pack.lzma (try 10/10)
Exception: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorExceptio… PKIX path building failed: sun.security.provider.certpath.SunCertPa… Unable to find valid certification path to requested target
Recognized exception: the likely cause is a set of broken/missing root-certificates. Check your java install and perhaps reinstall it.
Unable to download remote file. Check your internet connection/proxy settings.
FATAL ERROR: net.minecraft.bootstrap.FatalBootstrapEr… Unable to download while being forced
at net.minecraft.bootstrap.Bootstrap.execut…
at net.minecraft.bootstrap.Bootstrap.main(B…

Please fix the error and restart.}

How to improve Minecraft FPS?

So I just finished my first computer build which I made primarily for gaming. I anticipated getting higher FPS on the build than I did on my laptop, but I found that is not the case. On my MacBook Pro Retina (2.3 GHz i7, 8 GB 1600 MHz DDR3 RAM, GeForce GT 650M 1GB graphics card), I got around 30 FPS. I tested the same save on my build (i5 4670K 3.4 GHz, MSI Z87-G45 Board, 1 stick of 8 GB 1600 MHz RAM, no graphics card) and got 30 FPS as well. I was OUTRAGED when I added another stick of 8 GB RAM today (Up to 16 GB of RAM) and received once again, you guessed it, 30 FPS. Shouldn't I have seen a dramatic difference with the addition of 8 more GB of RAM, not to mention I'm know utilizing the Dual Channel memory with the second stick of RAM? I've heard optifine boosts FPS, but I can't see it improving my FPS 200% considering I have previously used it on my laptop and saw little to no difference. Whereas my friend receives on the upward of 120 FPS on his laptop which only has 4 GB of RAM, 2.3 GHz i7, and I believe a GT 650 as well. Was wondering what could help FPS for the time being, and if a graphics card would even display an improvement.

Which game sounds more interesting?

I make video games and I've narrowed my ideas down to two. The first one is a game where you can travel between cities and do whatever you want, almost like Grand Theft Auto. Unlike GTA, this will be a lot more realistic, just not to the point where it isn't fun anymore. It will also be in first-person instead of third-person. The other game is a game where you are stuck in the middle of the wilderness and you need to survive. This game is nothing like Minecraft because it doesn't have any fantasy stuff and the world isn't made of blocks. I had the idea of both of these games before I had ever played Minecraft or GTA, so they won't be too much like either of those games. Which one sounds more fun?

My Minecraft world will not load?

I have made a nice world, and a few months later my Minecraft world will not open, it will just be on the loading screen, and then it would go back to the title. I tried opening it multiple times but it still didn't work. Is there anyway to fix this problem?

Added (1). Thanks for answering Mia,
I did build huge structures, i have not blown up anything huge yet.
I tried to copy the world and it didn't work. Are there any other ways?

Minecraft: Replaces blocks?

This only happens on occasion but sometimes when I play Minecraft on singleplayer, not open to lan, the blocks I try to mine would blink when I break them and reappear. Then a few seconds later, the block would fall and I can obtain it. It doesn't seem to be lagging because when I walk around and do other things, it works fine, it's only when I try to mine blocks. Like I said, it only happens on occasion, but it's pretty annoying, is there anything I can do to fix it?

What game's should i record?

Hey so i made my own youtube channel (i know it may not be the best time, but i don't plan on partnering anytime soon, maybe even ever if thing's don't change.
Now i don't have much money maybe 10$ to spend on a game on steam maybe even up to 30$ depending on bills and how payed off they are after payday, i have recorded some minecraft, and lately been doing the F.E.A.R games (i have all the DLC for all 3 games… Well not Reborn but i plan on getting that soonish) but not entirely sure what to record while i take breaks from a game.

there are a few i was looking at, one was Magicka (the campaign one not the PvP one)
another was L4D2 i also have Starbound that i plan on recording with a friend once they do the character wipe and that is about it.

like i said i'm kinda poor lol and only have 10 - 30$ to spend after i pay rent and get food and other bills. I have been making my own channel art and so on, i will have an intro and outro sometime in the future.

anyway thanks for your help when ever anyone says anything.

My channel: http://www.youtube.com/...nlLI3RrExw