What is Temple, the small device seen on Deepinder Goyal’s head during a podcast?

Eternal founder Deepinder Goyal has grabbed eyeballs with a small device he was spotted wearing during a podcast. The small metallic device seen on the side of the entrepreneur’s head led to assumptions and jokes on the internet.

While some users joked it was a “chewing gum”, another commented it was “external SSD”. From “brainwashing” to “charging pads”, speculations were rife about the clip-like device.

But what is it actually?

Let’s take a closer look.

What is Goyal’s ‘Temple’?

Zomato CEO Deepinder Goyal, who appeared on Raj Shamani’s Figuring Out podcast recently, was seen wearing a silver-coloured device on the side of his head.

Dubbed ‘Temple’, it is a metallic-coloured clip-like wearable that he claims measures blood flow in the brain in real-time.

The experimental health-tech device can measure cerebral blood flow (CBF) in a similar manner as a “miniaturised” MRI, according to Goyal.

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The blood flow in the brain is essential for survival. It is said that CBF usually remains unchanged or minimally declines during ageing.

This is not the first time that Goyal was filmed wearing Temple. Last November, he said he had been wearing the device for a year.

“While conducting research on the Gravity Ageing Hypothesis, we had to make an experimental device to calculate Brain Flow accurately, in real-time, and continuously. Been using it for a year, and I’ve been feeling that this could shape into an important wearable the world needs,” the Zomato CEO said at the time.

The wearable comes amid Goyal’s personal research on the ‘Gravity Ageing Hypothesis’. He has announced $25 million (Rs 225.7 crore) funds fo research in human ageing and biological health. His health and wellness project, Continue Research, is looking into the reasons behind ageing.

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Temple is currently not a Zomato product and is not available for public or commercial use. However, the entrepreneur has teased that it is “getting there”.

Temple is a research prototype being developed under a health-tech startup of the same name, linked to Goyal’s Continue Research.

As per Goyal, Temple is designed to test whether long-term changes in brain blood flow could accelerate ageing.

What do experts say about ‘Temple’?

Experts say there is no scientific standing for devices like Temple that claim to monitor cerebral blood flow in real time.

A doctor at AIIMS Delhi called the device a “fancy toy” for billionaires with money to waste.

Dr Suvrankar Datta, a radiologist with clinical training from AIIMS Delhi, dismissed the device worn by Goyal as unscientific.

“As a physician-scientist and one of the earliest researchers in India in Arterial Stiffness and Pulse Wave Velocity (2017) which predicts cardiovascular mortality, I can assure you that this device currently has 0 scientific standing as a useful device,” Dr Datta wrote on X.

As a physician-scientist and one of the earliest researchers in India in Arterial Stiffness and Pulse Wave Velocity (2017) which predicts cardiovascular mortality, I can assure you that this device currently has 0 scientific standing as a useful device and do not waste your hard… https://t.co/pm0pxGRycd

— Dr. Datta M.D. (AIIMS Delhi) (@DrDatta_AIIMS) January 4, 2026

The AIIMS doctor advised people not to waste money on devices that have no scientific standing. “Do not waste your hard earned money to buy fancy toys billionaires can afford to waste money on. If you are one, then go ahead,” he said.

Speaking to NDTV, neurosurgeon Dr Vishwanathan Iyer from Mumbai’s Zynova Shalby Hospital said the place where the device sits raises a red flag as a senior on the temple can only capture surface-level signals.

“Such devices are designed to pick up surface-level signals, but they do not directly measure brain blood flow like an MRI,” he said, adding that MRI scans are complex hospital-based tests and cannot be replaced by a small wearable gadget.

Dr Iyer explained that while such sensors may record indirect indicators such as pulse or skin changes, these should not be confused with actual cerebral circulation. “This is not the same as measuring real brain activity or circulation,” he said.

Dr Iyer emphasised that there is a strong need for clinical evidence, until which Temple should be strictly seen as a wellness experiment, not a medical device. “People should be careful before spending money on them, especially if they are expecting medical benefits,” he added.

Zomato CEO’s ‘Gravity Ageing Hypothesis’

Goyal had earlier faced flak from experts over his ‘gravity ageing hypothesis’. In a series of posts on X last November, he claimed “gravity shortens lifespan”. The 42-year-old said he was not sharing the theory as the “CEO of Eternal, but as a fellow human”.

He even put forward three “known facts” to back his claims.

Reacting to Zomato CEO’s longevity theory, Dr Cyriac Abby Philips, popular as The Liver Doc on X, challenged Goyal’s claims with a series of tweets.

“He’s definitely sharing this as the CEO of Eternal because they are planning to build some sort of “device” that exploits vague areas in science and medicine or some cranky “longevity intervention,” which they want to claim negates the effect of gravity indirectly and sell it to gullible people who want to live forever," the hepatologist said.

Following the massive backlash, Goyal apologised and presented more theories to back his claims.

He said he had “miscommunicated" the key aspects of the theory. “I tried to compress years of research and thinking into a dramatic social media reveal. That made the hypothesis sound absolute and commercial – while it’s really not. I apologise.”

I did not explain the Gravity Aging Hypothesis (GAH) well, the first time.

I brought my consumer internet brain into a deep scientific field and I miscommunicated. I tried to compress years of research and thinking into a dramatic social media reveal.

That made the hypothesis… pic.twitter.com/I4dq0XkTPg

— Deepinder Goyal (@deepigoyal) November 20, 2025

According to Goyal, gravity lowers blood flow to the brain, contributing to ageing. “Brain Flow is already well accepted as a biomarker for ageing, longevity as well as cognition. So this device is useful and relevant even if the Gravity Ageing Hypothesis turns out to be wrong,” he said, referring to Temple.