How Edward managed to escape from Gluttony?


In Episode 24 and 25 of Fullmetal Alchemist: Brotherhood, Ed, Ling Yao and
Envy are trapped in a sub-dimension that was created for storing everything
that Gluttony has ever swallowed.

Envy told that there's no escape, but Ed has found out something. What did he
do exactly?

As far as I can get, he did human transmutation to open the Gate of Truth and
by this, he can escape. But how is it possible? Since the sub-dimension is
separated from the actual world.

Also, why Ed didn't lose anything when he opened the Gate again? Why Envy and
Ling neither?




Gluttony was created to be a second Gate of Truth but is only a failed copy.
Ed had the idea that because they came there through the failed gate, they
must be able to get back trough the real gate. It's just like creating a door
back to Gluttony.

To open the Gate of Truth, he used Envys Philisopher's Stone and the old parts
of the Xerxes mural to make this special human transmutation. The sacrifice
for opening the gate was a soul of the Philisopher's Stone, which thanked him
afterwards (because he freed the soul).




Gluttony was created to be a second Gate of Truth but is only a failed copy.
Ed had the idea that because they came there through the failed gate, they
must be able to get back trough the real gate. It's just like creating a door
back to Gluttony.

To open the Gate of Truth, he used Envys Philisopher's Stone and the old parts
of the Xerxes mural to make this special human transmutation. The sacrifice
for opening the gate was a soul of the Philisopher's Stone, which thanked him
afterwards (because he freed the soul).

