Any version older than 1.5.2 will be downloaded but fails to launch. I tried 1.4.7, 1.2, beta 1.7.3 and alpha 1.04.
Launcher 1.2.1 (through bootstrap 4) started on osx...
Current time is Aug 7, 2013 11:28:22 AM
System.getProperty('os.name') == 'Mac OS X'
System.getProperty('os.version') == '10.6.8'
System.getProperty('os.arch') == 'x86_64'
System.getProperty('java.version') == '1.6.0_51'
System.getProperty('java.vendor') == 'Apple Inc.'
System.getProperty('sun.arch.data.model') == '64'
Loaded 6 profile(s); selected 'Forge'
Refreshing auth...
Logging in with access token
Delta time to compare resources: 8324 ms
Download job 'Resources' skipped as there are no files to download
Job 'Resources' finished successfully
Getting syncinfo for selected version
Queueing library & version downloads
Download job 'Version & Libraries' started (8 threads, 11 files)
Finished downloading /Users/Wedhro/Library/Application Support/minecraft/libraries/net/java/jinput/jinput-platform/2.0.5/jinput-platform-2.0.5-natives-osx.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading /Users/Wedhro/Library/Application Support/minecraft/libraries/net/java/jutils/jutils/1.0.0/jutils-1.0.0.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading /Users/Wedhro/Library/Application Support/minecraft/libraries/org/lwjgl/lwjgl/lwjgl_util/2.9.0/lwjgl_util-2.9.0.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading /Users/Wedhro/Library/Application Support/minecraft/libraries/net/java/jinput/jinput-platform/2.0.5/jinput-platform-2.0.5-natives-osx.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading /Users/Wedhro/Library/Application Support/minecraft/libraries/net/java/jinput/jinput/2.0.5/jinput-2.0.5.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading /Users/Wedhro/Library/Application Support/minecraft/libraries/org/ow2/asm/asm-all/4.1/asm-all-4.1.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading /Users/Wedhro/Library/Application Support/minecraft/libraries/org/lwjgl/lwjgl/lwjgl/2.9.0/lwjgl-2.9.0.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading /Users/Wedhro/Library/Application Support/minecraft/libraries/net/minecraft/launchwrapper/1.5/launchwrapper-1.5.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading /Users/Wedhro/Library/Application Support/minecraft/libraries/org/lwjgl/lwjgl/lwjgl-platform/2.9.0/lwjgl-platform-2.9.0-natives-osx.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading /Users/Wedhro/Library/Application Support/minecraft/libraries/net/sf/jopt-simple/jopt-simple/4.5/jopt-simple-4.5.jar for job 'Version & Libraries': Used own copy as it matched etag
Finished downloading /Users/Wedhro/Library/Application Support/minecraft/versions/b1.7.3/b1.7.3.jar for job 'Version & Libraries': Used own copy as it matched etag
Job 'Version & Libraries' finished successfully
Launching game
Looking for old natives to clean up...
Unpacking natives to /Users/Wedhro/Library/Application Support/minecraft/versions/b1.7.3/b1.7.3-natives-1375867712695083000
Launching in /Users/Wedhro/Library/Application Support/minecraft
Running /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home/bin/java -Xdock:icon=/Users/Wedhro/Library/Application Support/minecraft/assets/icons/minecraft.icns -Xdock:name=Minecraft -Xmx1G -Djava.library.path=/Users/Wedhro/Library/Application Support/minecraft/versions/b1.7.3/b1.7.3-natives-1375867712695083000 -cp /Users/Wedhro/Library/Application Support/minecraft/libraries/net/minecraft/launchwrapper/1.5/launchwrapper-1.5.jar:/Users/Wedhro/Library/Application Support/minecraft/libraries/net/sf/jopt-simple/jopt-simple/4.5/jopt-simple-4.5.jar:/Users/Wedhro/Library/Application Support/minecraft/libraries/org/ow2/asm/asm-all/4.1/asm-all-4.1.jar:/Users/Wedhro/Library/Application Support/minecraft/libraries/net/java/jinput/jinput/2.0.5/jinput-2.0.5.jar:/Users/Wedhro/Library/Application Support/minecraft/libraries/net/java/jutils/jutils/1.0.0/jutils-1.0.0.jar:/Users/Wedhro/Library/Application Support/minecraft/libraries/org/lwjgl/lwjgl/lwjgl/2.9.0/lwjgl-2.9.0.jar:/Users/Wedhro/Library/Application Support/minecraft/libraries/org/lwjgl/lwjgl/lwjgl_util/2.9.0/lwjgl_util-2.9.0.jar:/Users/Wedhro/Library/Application Support/minecraft/versions/b1.7.3/b1.7.3.jar net.minecraft.launchwrapper.Launch Wedhro token:cdd4432a0fcd4aa190ee10b1c006beb8:12376c3e417248148dc3a7271d9863f8 --gameDir /Users/Wedhro/Library/Application Support/minecraft --assetsDir /Users/Wedhro/Library/Application Support/minecraft/assets
Client> 7-ago-2013 11.28.33 net.minecraft.launchwrapper.LogWrapper log
Client> INFO: Using tweak class name net.minecraft.launchwrapper.VanillaTweaker
Client> 7-ago-2013 11.28.33 net.minecraft.launchwrapper.LogWrapper log
Client> INFO: Launching wrapped minecraft
Client> 16 achievements
Client> 151 recipes
Client> Turning of ImageIO disk-caching
Client> Loading current icons for window from: /Users/Wedhro/Library/Application Support/minecraft/assets/icons/icon_16x16.png and /Users/Wedhro/Library/Application Support/minecraft/assets/icons/icon_32x32.png
Client> Invalid memory access of location 0x0 rip=0x0
Client>
Game ended with bad state (exit code 139)
Ignoring visibility rule and showing launcher due to a game crash
Deleting /Users/Wedhro/Library/Application Support/minecraft/versions/b1.7.3/b1.7.3-natives-1375867712695083000
Related issues
duplicates
Comments


Also:
This ticket is invalid as it relates to a modified or 3rd party, client, server, or launcher.
Any non-standard client/server/launcher build needs to be taken up with the appropriate team, not Mojang.
Any plugin issues need to be addressed to the plugin creator.
This site is for addressing issues related to the base unmodded Minecraft.

Duplicate of MCL-1433 in favour to the better description provided there.
Old versions are not supported as stated by the pop up you get when trying to launch them.