How physics can explain the origin of life

What is the problem?

Physics is the science that studies how matter and energy behave in the universe. Physics can explain many things, such as how stars and planets form, how light and sound travel, and how atoms and molecules interact. But physics does not have a good way to explain how life began and evolved on Earth, or how living things are different from non-living things.

What is the solution?

A group of scientists have proposed a new theory called assembly theory, which tries to bridge the gap between physics and biology. Assembly theory says that we can define any object by how it was made from smaller parts, called building blocks. For example, a Lego house is made by joining Lego bricks together in a certain way. Assembly theory also says that there are many possible ways to make different objects from the same building blocks, but only some of them are actually realized in nature. This is because some objects are more likely to be copied or selected than others, depending on the physical laws and the historical events that happened before.

How does it work?

Assembly theory uses two numbers to measure how complex and selected an object is: copy number and assembly index. Copy number is how many copies of an object exist in a given collection. For example, if you have 10 Lego houses and 5 Lego cars, the copy number of Lego houses is 10 and the copy number of Lego cars is 5. Assembly index is how many steps it takes to make an object from the smallest building blocks. For example, if you need 100 Lego bricks to make a Lego house, and each brick is one step, then the assembly index of a Lego house is 100.

Assembly theory says that an object with a high assembly index and a high copy number is evidence of selection¹. This means that the object has a special function or advantage that makes it more likely to be copied or preserved than other objects. For example, a DNA molecule has a high assembly index because it is made of many atoms joined together in a specific order. It also has a high copy number because it can replicate itself inside living cells. This shows that DNA molecules are selected for their function of storing genetic information.

Assembly theory also says that selection changes the way objects are made in nature. When there is no selection, objects are made randomly from the available building blocks. When there is selection, objects are made based on what already exists and what works better. This means that selection creates new possibilities and limits old ones in the process of making objects.

Why is it important?

Assembly theory is important because it can help us understand how life emerged from non-life, and how living things became more complex and diverse over time. Assembly theory can also help us identify signs of life on other planets, by looking for molecules with high assembly indices that are not likely to be formed by chance. Assembly theory can also help us study how technology evolves, by looking at how humans create new objects from existing ones based on their needs and preferences.

Assembly theory is a new and radical idea that tries to explain how physics creates all biology’s complexity. It may not be the final answer, but it is a promising step towards solving one of the biggest mysteries of science.

Assembly Theory in Detail

Copy Number

The copy number is a measure of how many copies of a particular object exist within a given collection. For example, if you have a box of Lego bricks and you’ve built 10 houses and 5 cars, the copy number for the Lego houses is 10, and for the Lego cars, it’s 5.

In the context of biology, if we consider a population of bacteria, the copy number would refer to how many bacteria are present. If a particular type of bacteria is more suited to its environment, it will reproduce more and increase its copy number.

Assembly Index

The assembly index is a measure of the complexity of an object. It’s calculated based on the number of steps required to assemble an object from its smallest building blocks. For instance, if you’re building a Lego house that requires 100 bricks, each brick represents one step in the assembly process. Therefore, the assembly index for this Lego house would be 100.

In biological terms, think about assembling a protein from amino acids. The assembly index would be the number of amino acids required to build that protein.

Evidence of Selection

When an object has both a high assembly index and high copy number, it’s considered evidence of selection. This means that this particular configuration provides some sort of advantage that makes it more likely to be replicated or preserved.

For example, DNA molecules have a high assembly index because they’re composed of many atoms arranged in a specific sequence. They also have a high copy number because they can replicate themselves within living cells. This indicates that DNA molecules are selected for their function in storing and transmitting genetic information.

Impact of Selection

Assembly theory suggests that selection influences how objects are assembled in nature. In the absence of selection, objects are assembled randomly from available building blocks. However, when selection is at play, objects are assembled based on existing structures and what configurations work better. This means selection introduces new possibilities and constraints in the assembly process.

Importance of Assembly Theory

Assembly theory can provide insights into how life emerged from non-life and how living organisms evolved to become more complex and diverse over time. It can also help us identify signs of life on other planets by looking for molecules with high assembly indices unlikely to form by chance alone.

Moreover, assembly theory can be applied beyond biology to study how technology evolves, examining how humans create new objects from existing ones based on their needs and preferences.

Applying Assembly Theory

In Biology

In the context of biology, assembly theory can be used to study the evolution of life forms. For example, consider a population of bacteria in a petri dish. If a mutation occurs in one bacterium that allows it to use a new food source, this bacterium will have an advantage over others. It will reproduce more, increasing its copy number. The new trait (ability to use the new food source) increases the assembly index of the bacterium as it adds complexity to its genetic makeup. Over time, this bacterium’s descendants will dominate the population, demonstrating the principle of natural selection.

In Technology

In technology, assembly theory can be used to understand how new technologies evolve from existing ones. For instance, consider the evolution of mobile phones. The first mobile phones were large and had limited functionality. Over time, engineers and designers selected features that users found useful and desirable, such as compact size, touch screens, internet connectivity, and apps. These features increased both the copy number (more phones with these features were produced) and the assembly index (phones became more complex). This process is analogous to natural selection in biology.

In Astrobiology

In astrobiology, assembly theory could be used to search for signs of life on other planets. Scientists could look for molecules with high assembly indices that are unlikely to form by chance alone. For example, complex organic molecules like amino acids or nucleotides could indicate the presence of life.

Conclusion

Assembly theory is a promising new approach that could revolutionize our understanding of how life originated and evolved on Earth and possibly elsewhere in the universe. It provides a quantitative framework for studying complexity and selection in both biological and technological systems. While it’s still a new theory and much work remains to be done, it’s an exciting step forward in our quest to understand the nature of life and its place in the universe.