3 ms·
There was observation - see his paper - http://calteches.library.caltech.edu/1801/1/zwicky.pdf http://calteches.library.caltech.edu/1801/1/zwicky.pdf - they saw
by madaxe_again 11y ago
There was observation - see his paper - http://calteches.library.caltech.edu/1801/1/zwicky.pdf http://calteches.library.caltech.edu/1801/1/zwicky.pdf - they saw the particles streak up out of the atmosphere, and measured their speeds.