The idea that human beings are at level 3 on a seven-level scale based on our ability to harness energy is an intriguing proposition that invites a rich exploration of our species' relationship with energy. While this specific framework isn't recognized in formal scientific literature, it's an insightful model that provides a novel perspective on our technological progress and potential future.

To frame this discussion, we can draw inspiration from the Kardashev scale, a hypothetical measure proposed by Russian astrophysicist Nikolai Kardashev in 1964. Kardashev proposed a three-tiered scale based on a civilization's ability to harness energy, but for this conversation, we will expand it to seven levels.

At level 1, we might imagine forms of life that harness energy directly from their immediate environment with little to no modification. This level represents organisms like plants (utilizing photosynthesis), or simple life forms harnessing energy directly from chemical sources.

Level 2 could represent creatures that have developed mobility, enabling them to actively seek out energy sources rather than relying on what is immediately available. This level includes most animals, which consume other organisms to meet their energy needs.

Humans, at level 3 in this model, have gone beyond immediate survival needs and harnessed energy to modify the environment and develop technology. We've discovered fire, invented the wheel, harnessed the power of the wind and water, unearthed the potential of fossil fuels, and split the atom. However, we remain confined to our planet in terms of energy harnessing, and our activities often have significant environmental impact.

At level 4, we might envision a civilization that has mastered planetary energy. Such a civilization could harness the total energy output of its home planet. Imagine technology capable of capturing and utilizing all energy from a planet's core or controlling and harnessing weather systems. This level would require a delicate balance of utilizing resources without causing environmental damage.

Progressing to level 5, this would encapsulate civilizations harnessing energy at a stellar scale, similar to a Type II civilization on the Kardashev scale. These civilizations could utilize the full energy output of their host star, possibly through megastructures like Dyson spheres or swarms. They might also harness energy from other celestial bodies within their solar system.

Level 6 civilizations could have reached a galactic scale of energy harnessing, corresponding to Kardashev's Type III. They would be able to utilize the energy from multiple stars, perhaps even all stars within their galaxy. This level would require unfathomable levels of technological prowess and logistical coordination.

At the apex, level 7 might represent civilizations capable of harnessing energy at a universal or multiversal level. This is beyond our current understanding of physics and would presumably involve harnessing the energy of black holes, dark matter, or even tapping into the cosmic microwave background radiation left over from the Big Bang.

This expanded model offers a grand perspective on our species' technological progress and potential. Currently, on this scale, humanity is at the early stages of level 3, still grappling with sustainable energy practices. However, with advancements in renewable energy, nuclear power, and potential future technologies like fusion, we are taking steps towards higher levels.

However, it's crucial to remember that progress isn't just about technological advancements. As we climb this hypothetical scale, we must consider the ethical implications of our energy harnessing, ensuring it doesn't lead to environmental degradation or social inequity. Sustainable progress involves not only developing new technologies but also making sure they benefit all of humanity while preserving the planet.

In conclusion, contemplating such a model can inspire us to dream about our civilization's potential while grounding us in the practical and ethical considerations that come with progress. Our relationship with energy is a defining aspect of our civilization, and as we look to the future, it's clear that finding sustainable, equitable, and efficient ways of harnessing energy will be key to our advancement.