Following is a summary from Chapter 20 of Leonard Susskind's 2008 book THE BLACK HOLE WAR: I'd appreciate any further insights, especially on interpreting what Susskind says about String theory as it was vague for me. These are not exact quotes. Elementary particles are usually imagined to be very small objects. Quantum Field Theory(QFT) and string theory share the property that that things appear to change as the resolution of experiments increases. Elementary particles appear so small because we can only see the portion revealed by low resolution (low energy) investigations. Experiments do not seem to be able to reveal the outlying high frequency vibrating structures. QFT at higher and higher resolution would reveal further internal structure, a reduction in a blurred image via finer resolution detail would reveal ever more detail from atoms, to a nucleus, to protons and neutrons, to quarks, etc. Things inside of things describes QFT. String theory in contrast reveals an increasing amount of structure; the complex structure grows and occupies more space as we see higher frequency quantum jitters. Most of the quantum jitters are too fast to observe currently. Analogies: As a small particle approaches a black hole, the particle appears perfectly normal to an accompanying free falling observer. Eventually its pulled apart by gravitational forces as it gets closer to the singularity. But to an external observer, the particle is smashed apart and spread it over the stretched horizon#. It’s content is reflected in the information of the stretched horizon and any resolution is dependent on possible long wave Hawking radiation that would be emitted. #The stretched horizon is a thin layer of hot microscopic degrees of freedom a planck length outside the event horizon... My own comment: Seems like the Schrodinger wave equation, de Broglie wave- particle duality, and maybe Feynman sum over paths also hint at a large (extended) size for what we often experimentally observe as “small” particles. If there isn’t an as yet undiscovered unifying theory underlying all of this, it sure seems like an awful lot of circumstantial evidence exists for one.