The Radical Isotopes are elemental isotopes that usually are unable to exist in our reality, since they have a negative mass, which breaks every law of physics known to the sentient races of the universe. However, they originate from the Abyss' Pocket Universe and could be of help in defeating it. Agents of the Abyss have the isotopes in their bodies, as a result of being possessed or affiliated with the Abyss. When Agents of the Abyss are asked the question, "From the beginning, what are the ten radical isotopes?", they must answer and reveal themselves as Agents of the Abyss.
When they were first mentioned, both Seamus Harper and Rommie stated that they were all prime numbers and that negative atomic mass should be impossible. Harper told Dylan Hunt that it would be like a "planet having a negative number of moons".
In C.Y. 10090, Doctor Professor Kor-Kavo unwittingly revealed the Spirit of the Abyss's presence, which had infiltrated a meeting of famous scientists. The Radical Isotopes also indicate the Abyss' presence in a person. The presence of the radical isotopes helped the crew of the Andromeda Ascendant determine the “presence” of the Abyss in Beka's brain. ("Chaos and the Stillness of It", "Lost in a Space that Isn't There", "Machinery of the Mind", "Time Out of Mind")
- Tucharium, Negative 5 (Boron)
- Dongor, Negative 17 (Chlorine)
- Lu, Negative 31 (Gallium)
- Kartex, Negative 79 (Gold)
- Sharbar, Negative 101 (Mendelevium)
- Ulanium, Negative 127 ()
- Hyduron, Negative 173 ()
- Simonsium, Negative 211 ()
- Metite, Negative 239 ()
- Krasnov, Negative 307 ()