> 3) When the speed at wich the atoms gets near the speed of light they will get heavier

They don't, but the overall mass of the object increases as its energy content increases.

In principle this would be possible, but no material can get anywhere close to the temperature it would need without flying apart. To avoid that, you could try to heat it extremely quickly - have a giant array of (to be developed) gamma ray lasers all focused on the same spot. But if you can do that then you can skip the target - the light pulses alone will be sufficient to make a black hole (kugelblitz.

You're not that far off.
Imagine you'd want to look at the tiniest possible scale through a microscope. The smaller the scale, the higher wavelength of light you need through your microscope. Imagine it as a light beam shining onto the particle you want to look at, mounted parallell to your microscope lens. You get to a certain point, let's imagine it's a particle, but you want even closer. You want to see what it is that this particle is made up of. When the thing you want to look at gets smaller than 10 to the minus 33 centimetres (the Planck scale), you will need a light with a wavelength so high that the energy it contains (energy = mass) actually creates a black hole. It may be hard to believe, but it is a fact. The light = energy = mass, and it gets that massive.

[removed]

[removed]

[removed]

[removed]