Arushi Nath

The 75th Regeneron International Science and Engineering Fair (ISEF) was held from May 10th to 17th, 2025, in Columbus, Ohio, is the world’s largest annual STEM competition for pre-college students. This year it brought together nearly 1,700 young scientists from over 60 countries, showcasing their research across 22 categories spanning science, engineering, and mathematics.

Following a Canada-wide selection process, I was honored to be chosen as one of eight individuals representing Team Canada at ISEF 2025. It was a privilege to represent Canada on the international stage.

My research entry was “NEPTUNE: Novel Exoplanet Prediction Technique Using N-body simulations, Bayesian Estimation, and Machine Learning” on which I had been working for the past year and had spent over 800 hours over weekend and during weekday evenings.

NEPTUNE is an accelerated approach designed to detect unseen exoplanets by analyzing Transit Timing Variations (TTVs) of known planets. Traditional exoplanet detection methods often overlook multi-planet systems containing long-period or non-transiting planets due to observational biases favoring short-period transiting planets. NEPTUNE bridges this gap by using N-body simulation to analyze Transit Timing Variations (TTVs) of known planets to detect, characterize, and assess the habitability of possible unseen companions.

I entered the project under the ISEF’s Physics and Astronomy Category which had almost 80 submissions from other countries. Projects in this category spanned a diverse range, from quantum computing and artificial intelligence to spectroscopy and astrophysical phenomena. The project was well-received and I had 7 individual judging interviews of 15 minutes each. It was a very proud moment for me when my name was called on the stage to have won the Third Grand Award.

Day 0: Arrival

Members of Team Canada traveled from across the country: from British Columbia, Ontario, and Saskatchewan to meet at Toronto Pearson Airport. We were joined by two delegates who accompanied us throughout our trip, assisting us with logistics, preperation and ensuring everything went smoothly. After gathering, we flew together to Columbus, Ohio, and settled into our hotel, ready for the week ahead.

Day 1: Project Setup and Pin Exchange

Our first day at ISEF was dedicated to setting up our project booths. The event took place at the Columbus Convention Center, conveniently connected directly to our hotel. After completing registration and receiving our name tags, we proceeded to the main hall to locate our designated booth sections based on our project categories. ISEF provided standard 48×48-inch poster boards along with header boards to display our projects. Since my poster exceeded the provided height, I stacked two trifold boards atop one another to accommodate my materials.

To finalize the setup, each project required approval from two display and safety inspectors, who verified compliance with all official guidelines and safety regulations.

In the evening, we participated in the lively pin exchange event. Finalists from around the globe brought pins, stickers, and small souvenirs symbolizing their hometowns and countries, which we eagerly exchanged. This tradition provided an exciting and enjoyable opportunity to meet and connect with fellow students from diverse cultural backgrounds.

Day 2: International Shout Out and Opening Ceremony

Each year, ISEF hosts a cultural showcase where participants from each country present a poster and short video highlighting their national identity. Together with two fellow Canadian finalists, we created a dynamic 5-7 second video capturing Canada’s unique spirit.

Throughout the day, various symposium sessions covered topics such as college applications, STEM outreach, creativity, and innovation. The evening’s opening ceremony marked the special milestone of ISEF’s 75th anniversary. We arrived early, securing excellent seats near the stage.

The ceremony began with a memorable recap video, highlighting the competition’s growth and significant impact over the decades. The event was hosted by Barb Baker and featured inspiring speeches from Maya Ajmera, President and CEO of the Society for Science and Publisher of Science News, and George D. Yancopoulos, co-founder and Chief Scientific Officer of Regeneron, who shared his personal journey and motivations for founding the company.

Following the speeches, a panel discussion took place, featuring distinguished leaders such as Frederick Berkely (President and CEO of COSI and CEO of the National Veterans Memorial and Museum), Jenny Britton (Founder of Jeni’s Splendid Ice Creams and CEO of Flora), Lewis Von Thaer (President and CEO of Battelle), and Ted Carter (President of Ohio State University and an ISEF alumnus). They emphasized the importance of STEM education, shared insights about aligning their professional work with public benefit, and provided valuable advice to aspiring young scientists.

The ceremony concluded with the International Shout Out, where each participating country was introduced individually. We proudly stepped onto the stage with our Canadian poster and presented our short video showcasing Canadian culture.

Day 3: Media Interviews and COSI Museum

The third day began early, with all finalists heading to their project booths for media interviews. Representatives from the Society for Science media, as well as external media outlets, visited various projects throughout the morning.

Afterward, we visited the Center of Science and Industry (COSI) museum. We enjoyed a variety of interactive exhibits and activities, including the High-wire Unicycle, speed and strength challenges, electric shock machines, and a motion simulator.

Following our museum visit, we returned to the hotel to relax and prepare for the judging scheduled for the next day.

Day 4: Judging and Finalist Mixer

We woke up early for judging, which was organized into two approximately three-hour sessions, separated by a lunch break. Upon arriving at our posters, we received a schedule listing our assigned judges and their time slots. Additionally, unexpected judges and special award judges could also visit at any time.

I had seven judges, with each judging session lasting 15 minutes. Some judges requested a brief presentation first, while others, having reviewed my project materials and poster beforehand, moved directly to questions. It was an amazing experience presenting my work to experts in astronomy and physics. I got questions ranging to my project’s inspiration to more technical inquiries regarding N-body integrators, machine learning setup, Bayesian inference processes, and associated uncertainties.

After judging concluded, we attended the finalist mixer, a relaxing event with a variety of foods and desserts. Activities included axe throwing, ping pong, inflatable obstacle courses, basketball, and a lively dance floor. The mixer provided a wonderful opportunity to socialize with finalists from other countries.

A Closer Look at the Judging

I had seven judges across two judging blocks of about three hours each, fifteen minutes per judge, and unannounced special award judges could arrive at any point as well. All judges had their own way of working. The first judge skipped the presentation entirely and went straight into questions, pointing at parts of the poster and asking me to explain them. The second and third judges let me present with only small interruptions for clarification. The fourth stopped me midway to press on how I knew Kepler-1710 was in resonance, and how I could be sure. The fifth had read my board and supplementary materials the night before and asked for a short summary instead. The sixth arrived with questions written down from the previous day. The seventh let me get about seven minutes in, then stopped me after every sentence or two to define a term or push one step further.

Fifteen minutes is not long enough to give a talk, so the format is really an examination. The questions came from every direction, from the physics to the code to why I had done any of it at all. Some of the more interesting ones:

On the physics behind NEPTUNE

• What is a perturbing planet, and what does M⊕ mean?
• What is the synodic period? What is resonance? What is apsidal precession?
• How do you know Kepler-1710 is in resonance, and how can you be sure?
• Why do eccentric orbits produce larger TTV amplitudes?
• Explain how you eliminated that solution.

On the tools I used for simulations and analysis

• Why Python? Why random forest, and did you try other models first?
• Which integrator did you use, and why?
• How does Lomb-Scargle work mathematically, and why not a Fourier transform?
• Did you write your own MCMC, or use an existing library?
• How long does your code take to run, and can it handle several planets at once?

The harder ones

• Could 80,000 simulations be causing overfitting? Might the solution simply lie inside one of those simulations already?
• If you train only on synthetic data, how do you know the results hold for real observations?

On how the work was done

• Why make it open source, and how much expertise does it take to run?
• Do you plan to continue this alone, or collaborate?

On why it matters

• In one short sentence, what is the broad impact of your project?
• What is the next step to turn Kepler-1710 into a confirmed multi-planet system?

I was able to confidently answer the questions presented to me. On reflecting back, I had prepared for even harder questions, especially on binning, the physics of the N-body simulations, my parameter ranges, and Nyquist sampling. None of those came up.

The written feedback afterwards picked out the part I had been least certain would land: "Discussion on degeneracies using synodic period and synodic amplitudes is novel and innovative." It also said the poster carried too much text, and that I should add simpler figures at the start for readers who are not astronomers. Both notes were fair.

Day 5: Public Outreach, Category Networking, North Market, and Special Award Ceremony

The fifth day was dedicated to public outreach, allowing students and families from Columbus and beyond to explore the projects. It also provided an excellent opportunity for us to visit other projects within our categories and learn more from our peers.

Later, we attended category networking sessions hosted by our respective category sponsors. My category, Physics and Astronomy, was sponsored by Jane Street. During our session, we engaged in solving complex puzzles collaboratively. The sponsor also provided fun merch like fidget toys, hats, and pins.

In the afternoon, Team Canada visited North Market, a bustling public market featuring Ohio’s finest independent merchants, farmers, and makers. We explored various stalls and enjoyed lunch. The day concluded with the special awards ceremony at the convention center.

Day 6: Grand Award Ceremony and City Tour

The final day began early with the grand award ceremony. Awards were announced category by category, beginning with fourth, third, and second places, concluding with the first place and top awards. I was honored to receive the third grand award in my category.

Afterwards, Team Canada explored Columbus, visiting landmarks such as the Ohio Statehouse and the German Village Book Loft. We spent the evening packing and preparing for our early morning flight home the next day.

Links:

List of Finalists

Award Ceremony

List of All Award Winners

Toronto Student Arushi Nath Wins International Award for Exoplanet Discovery Project at Regeneron ISEF 2025