Like dark energy, dark matter has never been detected directly.
Important as it is, the Higgs field cannot be detected directly.
Neither dark energy nor dark matter has been observed or detected directly.
Although frame dragging has not been detected directly, astronomers say it has been measured indirectly.
But dark matter itself is not only invisible, it has never been detected directly or indirectly by other means.
In that case, the Higgs exists too briefly to be detected directly either, but it decays into a characteristic spray of other particles that can be seen.
The energy cannot be detected directly, but physicists can use that friction to shake up the field and knock a new particle from it: the Higgs boson.
Most physicists believe that the dark matter particles have not yet been detected directly, although some experiments to find it have reported suggestive results.
For example, serum calcium concentrations are detected directly by calcium receptors in the parathyroid glands, and blood glucose concentrations are detected directly by the beta cells of the islets of Langerhans.
It has never been detected directly and it's true nature is one of the greatest unanswered questions in modern astrophysics.
Many physicists believe the dark matter will turn out to be swarms of particles predicted by their theories but not yet detected directly in particle accelerators here on Earth.
