Ch1.相对性原理：2间隔

<p style="color:#333333;font-weight:normal;font-size:16px;line-height:30px;font-family:Helvetica,Arial,sans-serif;hyphens:auto;text-align:justify;">两事件的间隔、类时间隔、类空间隔</p><span><br /></span><p style="color:#333333;font-weight:normal;font-size:16px;line-height:30px;font-family:Helvetica,Arial,sans-serif;hyphens:auto;text-align:justify;"><img data-key="0" alt="" src="http://imagev2.xmcdn.com/group88/M08/E8/D6/wKg5DF93yuTB1bmVAAn_xvshmbU844.JPG!op_type=4&amp;device_type=ios&amp;upload_type=attachment&amp;name=mobile_large" data-origin="http://imagev2.xmcdn.com/group88/M08/E8/D6/wKg5DF93yuTB1bmVAAn_xvshmbU844.JPG?op_type=0" data-preview-height="59.25925925925925" data-preview-width="140" data-preview="http://imagev2.xmcdn.com/group88/M08/E8/D6/wKg5DF93yuTB1bmVAAn_xvshmbU844.JPG!op_type=4&amp;device_type=ios&amp;upload_type=attachment&amp;name=mobile_small" data-large-height="317.46031746031747" data-large-width="750" data-large="http://imagev2.xmcdn.com/group88/M08/E8/D6/wKg5DF93yuTB1bmVAAn_x...