Dark matter as particles seems like a natural case to me: 1. We know that some particles don't see some forces, e.g. leptons don't experience the strong nuclea

Dark matter as particles seems like a natural case to me: 1. We know that some particles don't see some forces, e.g. leptons don't experience the strong nuclear force. So it's natural to expect particles that don't see the electromagnetic force. 2. Dark matter and ordinary matter do interact through gravity, which is the force that governs cosmic structures. So the distribution of dark and normal matter will be naturally related.