A computer mouse is a very light object - pick yours up and see what I mean.
Oh, if you are a gaming nerd or a computer freak you might have one of the types that has a joystick and a gun button and a dozen different adjustments - and always runs out of battery power halfway through a game...Those are serious electronic interfaces and can be the size of a loaf of bread. But the average mouse is a tiny thing.
Not that they are not still dangerous - spend all day steering one over a desk while locked into a plastic office chair and see what it does to the muscles and tendons of your wrist. Also see what sitting all day in that chair does to your waistline. Be warned.
Okay - translate these thoughts to the camera market, and start hefting the different models we have here on display. You may have just spent a month steering your computer mouse around the net looking for the best specifications, but I'll bet you were looking at megapixels and shadow detail and facial spot recognition rather than looking down into the mundane numbers in the weight and dimensions section.
Pick up the camera you thought was going to be the most fabulous - with the do-everything lens that had the best bokeh and got 15 and a half stars from Ken Rockwell. Hold it to your eye and see if your eye can see anything inside it. If it can, hold it there for a minute. Then hold it there for 4 more minutes. Then hold the camera in one hand for 15 more minutes without putting it down.
Can you feel your hand? If no, then you need the next model down on the list - the one that has been made with a lighter casing and less glass. Any camera user who wants to use it in the field for any period of time is going to have to support it and if the whole process becomes a weight-lifting rather than artistic exercise, all the tech specs that you read about last month won't amount to a hill of beans. You will be buried UNDER a hill of beans.
Take heart - Olympus, Fujifilm, Canon, Nikon, Panasonic, Sony, Pentax, and Leica all make lighter-weight cameras that produce marvellous results. Do not discount them ( and please do not ask US to discount them...) in your search for a travel camera. Be kind to yourselves.