Do thoughts have energy or they are in a energy field? During meditation when thoughts are there experience high energy and when the mind is calm experience less energy.
If every person on one side of the Earth jumps at the same time, it will not change the rotation of the Earth.
Similarly, the electrical and/or electromagnetic energy in or of your brain, while perceptible using EEG or other such instruments, does not make any noticeable difference in the physical world, in or out of meditation. It's relatively weak.
Theravada Buddhist Answer.
Conventionally speaking, yes mental phenomena might be described to have some kind of energy or momentum to them. Take anger for example, if its allowed to snowball it becomes completely uncontrollable, making beings perform unwholesome actions. In a way, one becomes a victim to anger. When anger snowballs, one can feel how momentum is build up.
Ven. Bhikkhu Bodhi describes anger as looking into a bowl of boiling water, not being able to see ones own reflection.
Having a still and peaceful mind is like looking into a lake with no surface ripples. One is able to clearly see the bottom of the lake.
Ultimately speaking, there are no such things as "energy or momentum" - these are concepts.
Here is a quote from a well written chapter, describing Ultimate Reality - its from the book "What Buddhists Believe" by Ven. K. Sri Dhammananda, p. 105-111:
The Abhidharma teaches that the egoistic beliefs and other concepts such as ‘I’, ‘you’, ‘person’ and ‘the world’ , which we use in daily conversation, do not adequately describe the real nature of existence. The conventional concepts do not reflect the fleeting nature of pleasures, uncertainties, impermanence of every component thing, and the conflict among the elements and energies intrinsic in all animate or inanimate things. The Abhidharma doctrine gives a clear exposition of the ultimate nature of human beings and brings the analysis of the human condition further than other studies known to them.
The Abhidharma deals with realities existing in the ultimate sense, or paramattha dhamma in Pali. There are four such realities:
Citta, mind or consciousness, defined as ‘that which knows or experiences’ an object. Citta occurs as distinct momentary states of consciousness.
Cetasika, the mental factors that arise and occur along with the citta.
Rupa, physical phenomenon or material form.
Nirvana, the unconditioned state of bliss which is the final goal.
Citta, the cetasika, and rupa are conditioned realities. They arise because of conditions, and will disappear when the conditions sustaining them cease to continue to do so. They are impermanent states. Nirvana, on the other hand, is an unconditioned reality. It does not arise and, therefore, does not fall away. These four realities can be experienced regardless of the names we may choose to give them. Other than these realities, everything—be they within ourselves or without, whether in the past, present or future, whether coarse or subtle, low or lofty, far or near—is a concept and not the ultimate reality.
Citta, cetasika, and Nirvana are also called nama. Nirvana is an unconditioned nama. The two conditioned nama, that is, citta and cetasika, together with rupa (form), make up psychophysical organisms, including human beings. Both mind and matter, or nama-rupa, are analysed in Abhidharma as though under a microscope. Events connected with the process of birth and death are explained in detail. The Abhidharma clarifies intricate points of the Dharma and enables the arising of an understanding of reality, thereby setting forth in clear terms the Path of Emancipation. The realization we gain from the Abhidharma with regard to our lives and the world is not to be understood in a conventional sense, but is an absolute reality.