Could I learn electric guitar from absolute scratch without any teacher?

Sure it can be done...You will have to practice for 4 or more hours a day if you want to get good enough fast enough...I started when I was 14 and Im 22 now...Within a few weeks I was better than all of my friends who had been playing for a year or so. I have never received a lesson from any one. I can sweep, shred, and play guitar at over 300 bpm. I have mastered multiple styles of music including clical guitar, folk, jazz, blues, rock, punk, technical death metal and neo clical shredding. Granted, I have practiced every day for 8 hours or more some times up to 16 hours...Anything worth doing takes work and a lot of it...I recently did the math and I have spent over 23000 hours practicing....just keep practicing as much as you can without hurting your self...You will regret any injuries sustained to your hands as they could take 6 months to heal. look up as many things on guitar as you can...you tube has a wealth of information.(I wish I had when I was your age)