I have calculated the longest possible chess game

nurses are good at that 

Does White or does Black have the last move in the longest possible game?

I don't believe you. But I am willing to let you try to convince me otherwise...

Oh now we can deviate from the chess chat lol

the 50 move rule resets after an irrevocable move. This memans a pawn move, a piece capture, or castling. You forgot about castling.

Are you sure that's the rule?

This website says otherwise.

@ MsJean

I'll play you a game of live chess; online chess takes an amount of time I won't have for a few years.

I don't know this website very well, so you'll have to "challenge" me.

Assuming the fastest players in the world played at full speed in a bullet match for   the whole match and that neither of them claimed a draw they could do around 6000 moves. These are the people with the fastest hands in the world.

One of them can stamp 100 a4 papers in 1 second.

lol..

I think the game is limited more by the aging off the humans playing (they will eventually die, you know) then by threefold repetition.

This is certainly theoretically correct as far as is practical to calculate; the only way to get a better result would be to actually look at every possible game (since your number is probably not really correct, since not all of those changes could happen in any one given game, but until we look at every possible game we cannot know this for sure).

I don't think they could even get close.

For a 2min bullet game, they would each on average have to make 25 moves in a second--and endure the whole 4 minutes.

About the 100 stamps, I'll only believe it if the papers were arranged in a highly convenient manner (involving momentum or multiple stamps at a time). Bullet chess requires much more motion.

 Yes they could get close. If their hands have stamina then they could endure the 4 minutes. And the 100 papers were not arranged conveniently, they were just in one pile.

Impossible.

Possible

I must agree with the improbable combination of r's and and x and a z. It takes a tenth of a second to blink, a fifteenth of a second to process an image from the eye, here you are telling me it takes a 25th of a second to pick up a piece and move it to the exact square you wish?

And don't forget hitting the clock!

There's no way they could play those moves in 0.04 seconds normally.  But since they are cooperating, they could make good use of premove.  They could also play a 1 1 bullet game... then they could take 1 full second per move.  This would obviously be the easier way.  

But you still need the stamina to play that many moves that quickly while keeping track of the move count, remembering whose turn it is to make a capture or move a pawn, and being careful to never repeat the position 3 times during each move set.  If each side took the full second per move in a 1 1 game, the game would be at the 3 hour mark around move 5400.  I'm not sure if I'd lose concentration first or if my hand would cramp up.  

That makes sense.

I have also been thinking about the longest possible chess game recently, when I came upon this thread.  I came to a similar answer as those of you that claim the longest game, limited by the 50-move rule, is 5898 moves.  But I claim that the longest game is actually 5898.5 moves, ending with one final move by white. 

Where my logic differs is that I claim the game can be played with only 3 switches in the responsibility of which player moves pawns and captures, whereas many posts here have claimed that it requires 4.  Some of the posts here seem to indicate that each team must capture with pawns 4 times, for a total of 8 pawn captures.  I claim that while 8 pawn captures total must occur, they need not be split equally in order to maximize the total number of moves that are either pawn moves or captures.  The example I'll give involves black making only 2 pawn captures, while white makes the other 6, though there are other ways to do it with only 3 switches in responsibility.

On the 50th move, black takes the responsibility for pawn moves and captures.  He captures two white knights with the two pawns that started in front of his bishops, as only the white knights can get out before white moves any pawns.  Note that white can also move rooks back and forth into the empty knight spots, if needed when both knights are captured.  Black will also need to advance both pawns that started in front of knights, such that they're ahead of his pawns that started in front of rooks. 

The first switch occurs now, and white takes the responsibility.  White must make 6 pawn captures and advance all 8 pawns to promotion during this period.  The pawns from in front the the knights capture inward, to move into the files of the bishop.  The pawns from in front of the king and queen capture outward, into the files of the bishop as well.  6 white pawns can now advance to promotion up the bishop files.  The white pawns in front the the rooks advance to the rank of the black pawns from the knights file and capture pieces inward, into the knight files.  Since the black pawns from the knight files had advanced beyond the black pawns from the rook files during black's first responsibility, the white pawns that have now captured into the knights file are past the black pawns from the same file, allowing these last two white pawns to continue advancing the rest of the way to promotion.  Note that 6 of 7 black pieces were captured, leaving black with a king, another piece, and 8 pawns.

The responsibility now switches a second time, back to black.  Black promotes all 8 pawns, with no white pawns left to block them, and captures all of white's pieces except the white king.

The responsibility switches a third and final time, back to white.  White's king captures all of black's remaining pieces except the king.  On the final capture of a black piece by the white king, the game ends in a draw due to insufficient material for checkmate with the king vs king endgame.  White makes this final move, ending the game at 5898.5 moves. 

On a somewhat different note, the longest game does not have to end in a draw, as some posts seemed in imply.  We could end with white achieving checkmate on the final move.  During black's second responsibility, he could have captured all of white's pieces except the king and a queen (or rook).  Then during white's final responsibility, after white captures all of black's pieces except the king with his king and queen, the game does not end.  We instead go an additional 50 moves with white king and queen vs black king.  These 50 extra moves exactly compensate for the 50 moves lost by black not taking white's last queen.  White has the final move, and the game will end at 5898.5 moves, regardless of what move white makes here.  White can choose to checkmate black using the queen on this final move.

Note that this checkmate on the final move was also possible with the four switch scheme described in earlier posts, with black remaining a queen (or rook) and achieving checkmate on the final move, ending at 5898 moves.