It seems absurd, but the truth is that digital files have weight. ‘It’s a very, very, very small weight, on the order of an atgram, but it’s not zero. However, your hand will never be able to perceive it.
A cell phone is a file of a very peculiar kind. You can save years of photos, thousands of messages, old songs, and recordings of voices you may never hear again. But seems to do so without increasing in size or weight.
According to physics, however, this can’t be true. In flash memory, each bit must be written to matter, through small changes in the energy states of electronic components.
This change in energy necessarily implies a change in masswhich suggests that a cell phone loaded with data should be heavier than a void.
In truth, that’s exactly what happensbut the difference is so tiny that no ordinary scale can detect it.
It may seem like a riddle, but think of it this way: imagine downloading thousands of books on your cell phone. Will it get heavier? This extra information brings with it extra dough?
«In principle, the answer is yes», explains John D. Kubiatowiczprofessor of computer science at the University of California, Berkeley, speaking to . «However, this quantity is very small, of the order of an atogram».
Kubiatowicz estimates that filling a Kindle with four gigabytes would add to its weight about one atogram, i.e. 10⁻¹⁸ gramsa quantity “practically impossible to measure”. It’s a trillion times less than a gram. It’s even smaller than some tiny viruses.
But it’s not zero. Technically, smartphones become heavier when they are filled with information. The same happens with computers, e-book readers or any other similar device.
We often talk about digital information as if it had no weight. The photographs live “in the cloud”. But inside a cell phone, nothing is ethereal. Each photograph stored is a physical arrangement — a pattern inscribed in memory.
In simple terms, flash memory cells distinguish between “states”imprisoned or not imprisoned” of electrons. A photograph, an app or a book is made up of millions or billions of electrons in these different states.
The important detail, notes , is that the trapped and non-trapped electrons they don’t have exactly the same energy. The trapped electrons are in a higher energy state. It is in this small energy difference that the extra mass resides.
Kubiatowicz notes that the effect is about a hundred million times smaller than the mass variation caused by loading and unloading of the battery. In other words, the state of the battery matters much more than the files stored — and even this variation is not something you experience on a daily basis.
You could argue that modern cell phones have a capacity well in excess of four gigabytes. But even scaling the estimate upwards, the result would only be about 10⁻¹⁶ gramsor 0.1 femtograms.
So, a cell phone full of photos is in fact technically heavier, but your hand has no chance of detecting it.
