Are the higher arupa jhanas supernatural states expanding beyond the physical body? The higher arupa jhanas are:

fifth jhāna: infinite space (Pāḷi ākāsānañcāyatanaa),
sixth jhāna: infinite consciousness (Pāḷi viññāṇañcāyatana),
seventh jhāna: infinite nothingness (Pāḷi ākiñcaññāyatana),
eighth jhāna: neither perception nor non-perception (Pāḷi nevasaññānāsaññāyatana)

Are these supernatural states?
Does the plane of infinite consciousness of the sixth jhana refer to the Universal Consciousness or Cosmic Consciousness of Advaita Vedanta?
Do the fifth, sixth and seventh jhana takes the meditator beyond his physical body and into infinite space, infinite consciousness and infinite nothingness?
Can the meditator now observe things in other galaxies by entering these states? Can they see what is happening in the deva or brahma worlds by entering these states? Can they sense through the senses of other living beings? Are they supernatural states of being?
Or are they simply different states of mind? That is, not supernatural.
I have also heard that they are related to compassion, loving kindness and other Brahmaviharas - how is this the case? Is there a clear connection?
Why are they described as formless (arupa)?
I would appreciate it, if canonical references (from the Pali Canon) are available to support this. Commentaries or secondary sources (e.g. Visuddhimagga, traditional commentaries, modern commentaries from scholar monks etc.) are also welcomed, in addition.
The canon does not mention them as Jhana but formless states, good householder Ruben, to mention that.
Are these supernatural states?
Yes, since based on the 4 Jhanas. Detail discussion on Parajika 4 on supernatural states in BMC might be useful.
Does the plane of infinite consciousness of the sixth jhana refer to the Universal Consciousness or Cosmic Consciousness of Advaita Vedanta?
Any answer here would be speculation for the most unless one would have attained also knowledge of what is thought of it in the Advaita Vedanta and Awakened to beyond as well. There is of course much reasonableness behind to compare it.
Do the fifth, sixth and seventh jhana takes the meditator beyond his physical body and into infinite space, infinite consciousness and infinite nothingness?
Yes: formless states
Can the meditator now observe things in other galaxies by entering these states? Can they see what is happening in the deva or brahma worlds by entering these states? Can they sense through the senses of other living beings?
Form, objects of the senses, are absent, so not very reasonable. Not forgetting that Dhamma can't be received as well here.
Or are they simply different states of mind?
The question doesn't make sense in regard of 'or'. Of course they are different states of mind.
I have also heard that they are related to compassion, loving kindness and other Brahmaviharas - how is this the case?
Best sample on it has been already given by Upasaka Karl.
General good advices and explainings on concentration, at least in regard of the aim of the practice *räusper*, can be found in Right Concentration in &quot;Wings of Awakening&quot;, generously by Bhante Thanissaro.
[Note that this has not been given for stackes, exchange, other worldbinding trades, but for release from this wheel.]