We begin with just the rubber sheet and the ant, simulating empty space with no mass in it.
1	We	we	PRON	PRP	Case=Nom|Number=Plur|Person=1|PronType=Prs	2	nsubj	2:nsubj	Discourse=organization-preparation:149->152:2|Entity=(53-person-giv:act-cf1*-1-ana)
2	begin	begin	VERB	VBP	Mood=Ind|Number=Plur|Person=1|Tense=Pres|VerbForm=Fin	0	root	0:root	_
3	with	with	ADP	IN	_	7	case	7:case	_
4	just	just	ADV	RB	_	7	advmod	7:advmod	_
5	the	the	DET	DT	Definite=Def|PronType=Art	7	det	7:det	Entity=(176-object-giv:inact-cf4-3-coref
6	rubber	rubber	NOUN	NN	Number=Sing	7	compound	7:compound	Entity=(177-substance-giv:inact-cf5-1-coref)
7	sheet	sheet	NOUN	NN	Number=Sing	2	obl	2:obl:with	Entity=176)
8	and	and	CCONJ	CC	_	10	cc	10:cc	_
9	the	the	DET	DT	Definite=Def|PronType=Art	10	det	10:det	Entity=(183-animal-giv:act-cf3-2-coref
10	ant	ant	NOUN	NN	Number=Sing	7	conj	2:obl:with|7:conj:and	Entity=183)|SpaceAfter=No
11	,	,	PUNCT	,	_	12	punct	12:punct	_
12	simulating	simulate	VERB	VBG	VerbForm=Ger	2	advcl	2:advcl	Discourse=purpose-goal:150->149:0
13	empty	empty	ADJ	JJ	Degree=Pos	14	amod	14:amod	Entity=(186-place-new-cf2-2-coref
14	space	space	NOUN	NN	Number=Sing	12	obj	12:obj	_
15	with	with	SCONJ	IN	_	19	mark	19:mark	Discourse=elaboration-attribute:151->150:0
16	no	no	DET	DT	Polarity=Neg|PronType=Art	17	det	17:det	Entity=(187-object-new-cf6-2-sgl
17	mass	mass	NOUN	NN	Number=Sing	19	nsubj	19:nsubj	Entity=187)
18	in	in	ADP	IN	_	19	case	19:case	_
19	it	it	PRON	PRP	Case=Acc|Gender=Neut|Number=Sing|Person=3|PronType=Prs	14	acl	14:acl:with	Entity=(186-place-giv:act-cf2-1-ana)186)|SpaceAfter=No
20	.	.	PUNCT	.	_	2	punct	2:punct	_
