The Merkaba is known in two different traditions, the Kamitic (Egyptian) and Jewish Mystical Tradition. Based on the Kamitic teaching Mer means: counter rotating fields of light, Ka, spirit and Ba, body or reality. In the Jewish Mystical Tradition it means chariot and relates to the experience of what was sighted in the vision of the Hebrew Prophet, Ezekiel in the first chapter of his book in the Bible. He saw the Chayot Haqadosch, The Holy Creatures that were in the form of a man, eagle, ox and lion. This vehicle also had Seraphim and Ophanim, two heavenly choirs of angels. There was also a figure of a man inside the vehicle operating it. The word, Merkaba, was often used in the Masoretic text to depict earthly conveyance in the form of chariots pulled by a terrestrial beast.
The whole Merkaba phenomena has taken another shift within the last twenty years with the New Age teacher, Drunvalo Melchizedec who teaches the breathing technique that activates the Merkaba Light Body. His technique activates light from the lower spinal column. In these series of eighteen breaths, one must first open up the heart chakra to receive divine love and then the cosmic connection is made with the tube of light that runs up through the kundalini channel. This will connect one with Mother Earth & Father Sky and eventually will create the light vehicle that envelopes the total being of the person. This includes the physical body not just the astral body. Many people voluntarily travel in their astral body, but to use a light vehicle as a conveyance of the physical body is something read about in legends and not fathomed by most humans.
To manifest those tasks that seem impossible, one must have a vast imagination and a high level of self confidence. There have been many historical recordings of mystics flying in the air in many traditions. There is a lot of blogs on the internet about contemporary Merkaba techniques. The key is the breath and becoming a more loving human being.
In relationship to the ancient Merkaba Mystical teachings, it is not so easy. It requires much contemplation, purification, pin-point angelic litanies and an ascetic lifestyle. Due to the fact that you must past the angels that guard the heavenly palaces, you must be “on point” or you could get obliterated by the light/fire.
I think that there is always need for some level of caution with diligent awareness. Ascension is not willy nilly like some people make you think. You must be righteous or you will get burnt, or travel to a hellish dimension full of torment. Human beings, for the most part, are quite toxic. Human beings have to get their diet together and program their minds and heart with the right knowledge.
I think that the aquirement of the Merkaba is possible but it requires a lot of positive programming. I believe in divine grace and I also believe that you must work hard for lofty expectations. The mind must change. The age we are in now has great opportunity for change available, but people have to come out of there delusional idea that God is far away from them. Only God can see God. If you like this Merkaba stuff, I advise you to do your research and find out what works for you.