Can an objective metric for good and bad exist?

The idea behind this is that good and bad are valuations within the mind, and therefore subjective. However, the existence and structure of minds are objective facts about the physical world, and such facts could be analyzed by a hypothetical metric we could call objective if it were precise and reliable enough.

For instance, when a person is in strong pain, or experiences strong pleasure, or strong repulsion by another's act which it observes as immoral, many scientists and philosophers would agree that there's something objectively measurable happening in that person's brain, and it could be identified, described, and maybe even quantified by an objective analytical metric.

Following this premise, it raises the question if there's a reliable way of deriving such a metric that's applicable to the human brain, and if it could be abstracted and generalized systematically in such a way that it could ultimately be applied as an objective descriptive tool to all kinds of physical systems, in order to determine the existence and maybe even quantity of good or bad within the scope of these systems.

Why do brains feel bad (or good)? A short answer is because these feelings evolved to motivate generally adaptive behavoir. A deeper answer would be to look at how brains feel bad (or good). We could describe exactly what's happening in the brain when it feels strongly bad (or good) and then, as a second step, generalize the description of that phenomenon so that we would recognize the hallmarks of its valuation-bearing informational properties in all other potential physical systems of equal complexity. Since ultimately, any idea of good and bad in human culture stems from how human brains feel about things, a generalizable descriptive metric of that phenomenon could be the ultimate objective description tool for good and bad in the universe.

In relation to this idea, I would like to pose these questions to discuss:

1. Is such a metric possible conceptually?
2. What steps could be taken to derive such a metric in practice?
3. If successful, how would this affect the is-ought-gap in ethics?
4. Would we, as individuals and societies, benefit from using such a metric?