<|im_start|>system
You are a helpful AI assistant.<|im_end|>
<|im_start|>user
what is dark matter<|im_end|>
<|im_start|>assistant
Dark matter is an hypothetical form of matter, which does not interact with the electromagnetic field. It is thought to account for approximately 85% of the matter in the known universe, if it does exist.<|im_end|>