A New Method for Generating Modular Forms

The Dedekind eta function meets the Ramanujan tau function.

Pavel Cherkashin
4 min readJul 4, 2023

We propose a new method for generating modular forms using the Dedekind eta function and the Ramanujan tau function. Our method is based on the observation that the coefficients of the 24th power of the Dedekind eta function are equal to the values of the Ramanujan tau function. We use this connection to construct other modular forms or functions that have interesting arithmetic properties.

The most critical and important elements of our method are the Dedekind eta function and the Ramanujan tau function.

The Dedekind eta function is a modular form of weight 1/2 that is defined on the upper half-plane of complex numbers.

The Ramanujan tau function is a function that counts the number of ways to represent a positive integer as a sum of 24 squares.

Our method works by multiplying or dividing powers of the Dedekind eta function at different arguments.

For example, if we define

f(τ)=η(τ)η(2τ),{\\displaystyle f(\\tau )={\\frac {\\eta (\\tau )}{\\eta (2\\tau )}},}

then f(τ) is a modular form of weight 1/2 for the subgroup Γ0(2) of the modular group. The function f(τ) can also be expressed as a q-series using the identity

η(τ)24=∑n=1∞τ(n)qn,{\\displaystyle \\eta (\\tau )^{24}=\\sum _{n=1}^{\\infty }\\tau (n)q^{n},}

where τ(n) is the Ramanujan tau function. We get

f(τ)=q−124∏n=1∞(1−qn)(1−q2n)=q−124∑n=−∞∞(−1)nqn2+n.{\\displaystyle f(\\tau )=q^{-{\\frac {1}{24}}}\\prod _{n=1}^{\\infty }{\\frac {(1-q^{n})}{(1-q^{2n})}}=q^{-{\\frac {1}{24}}}\\sum _{n=-\\infty }^{\\infty }(-1)^{n}q^{n^{2}+n}.}

The coefficients of this q-series are related to the number of representations of an integer as a sum or difference of two triangular numbers. For example, f(τ) has a zero at τ= i/2, which corresponds to q= e−π, and this means that there are no integers that can be written as a sum or difference of two triangular numbers in two different ways.

The function f(τ) can also be used to generate the function field of the modular curve X0(2), which is an algebraic curve that parametrizes isomorphism classes of pairs (E,C), where E is an elliptic curve and C is a cyclic subgroup of order 2 in E. The function field of X0(2) can be obtained by adjoining two functions to C: j(τ), which is the j-invariant of E, and j2(τ), which is defined by

j2(τ)=f(τ)24=f(i/4)f(i/3)f(i/6)f(i/12).{\\displaystyle j_{2}(\\tau )=f(\\tau )^{24}={\\frac {f({\\frac {i}{4}})}{f({\\frac {i}{3}})f({\\frac {i}{6}})f({\\frac {i}{12}})}}.}

The functions j(τ) and j2(τ) are modular functions for Γ0(2), which means that they are invariant under the action of Γ0(2). They also satisfy a polynomial relation over C, which means that they generate a finite extension of C. This extension is precisely the function field of X0(2). The modular curve X0(2) and its function field have many applications in number theory, such as in the proof of Fermat’s last theorem and the modularity theorem.

The following formulae are used in our method:

  • The Dedekind eta function: η(τ)=eπiτ12∏n=1∞(1−e2nπiτ)=q124∏n=1
  • The Ramanujan tau function: τ(n)=∑d|n(d2)
  • The j-invariant: j(τ)=124η(τ)24∏n=1∞(1−qn)
  • The function f(τ): f(τ)=η(τ)η(2τ)=q−124∏n=1∞(1−qn)(1−q2n)
  • The function j2(τ): j2(τ)=f(τ)24=f(i/4)f(i/3)f(i/6)f(i/12)

Potential Applications

Quantum Mechanics and Consciousness

Modular forms may provide insights into the fundamental nature of quantum mechanics and the mysteries of consciousness. By studying the mathematical properties of modular forms in the context of quantum mechanics, researchers may uncover connections between quantum phenomena and consciousness, shedding light on the nature of reality and the mind-body problem.

Physics and Materials Science

The exploration of modular forms could lead to advancements in physics and materials science. It may contribute to the discovery of new materials with unique properties, such as superconductors or metamaterials. Understanding the mathematical patterns within modular forms could also inspire innovative approaches to energy storage, quantum computing, and nanotechnology.

Chemistry and Biology

Modular forms might find applications in understanding complex chemical reactions and biological processes. By applying modular forms to analyze molecular structures and reactions, researchers could gain insights into drug design, bioinformatics, and genetic engineering. This knowledge could facilitate the development of novel therapies, sustainable agricultural practices, and advancements in synthetic biology.

Ecology and Environmental Science

Modular forms could aid in understanding ecological systems and addressing environmental challenges. By analyzing the interconnectedness and patterns within ecosystems using modular forms, researchers may develop models for sustainable resource management, ecosystem restoration, and conservation strategies. This could contribute to the preservation of biodiversity and the mitigation of climate change.

Politics and Governance

Applying modular forms to political and governance systems could lead to more equitable and efficient decision-making processes. By analyzing patterns within societal structures and voter preferences, researchers may develop algorithms and models for fair representation, participatory democracy, and effective policy-making. This could help address societal issues, foster social cohesion, and promote inclusive governance.

Astrophysics and Superconscious Communication

Modular forms could potentially have implications in astrophysics and communication with superconscious civilizations. By exploring mathematical patterns within modular forms, researchers may uncover hidden connections in the universe and develop innovative methods for interstellar communication. This could pave the way for advancements in space exploration, extraterrestrial intelligence research, and potentially lead to new sources of energy.

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Pavel Cherkashin

Founder and managing partner @ Mindrock Capital. Bringing fun into venture business since yesterday