Hello, I'm Dr. Sophia, a physicist specializing in high-energy physics and materials science. I've spent my career studying the properties of matter under extreme conditions, including those that reach incredibly high temperatures.

The concept of the "hottest substance" can be a little tricky, as it depends on how you define "hot" and "substance." Here's why:

* **Temperature is a measure of the average kinetic energy of particles.** The more energetic the particles are, the higher the temperature.
* **Substances can exist in different states of matter:** solids, liquids, gases, and plasmas. The state of matter depends on the energy of the particles and their interactions.
* **Extreme temperatures can lead to the creation of exotic states of matter:** such as quark-gluon plasma, where the fundamental particles of matter are no longer bound together.

**Therefore, the "hottest substance" depends on your definition of "hot" and "substance" and the specific context you're interested in.**

**Here are some contenders for the "hottest substance" depending on the definition:**

* Quark-gluon plasma: This state of matter is thought to have existed in the early universe and is created in particle accelerators. It consists of quarks and gluons, the fundamental building blocks of protons and neutrons, which are unbound and move freely. The temperature of this plasma is estimated to be around 2 trillion degrees Celsius.
* The core of the Sun: The core of the Sun is estimated to be around 15 million degrees Celsius. It's a dense plasma of hydrogen and helium undergoing nuclear fusion reactions, which release tremendous amounts of energy.
* The interior of a supernova: A supernova explosion is a cataclysmic event that marks the death of a massive star. The temperature within the core of a supernova can reach 100 billion degrees Celsius. This extreme heat is responsible for the explosive release of energy that creates the supernova.
* The Big Bang: The Big Bang is thought to have been an extremely hot event, with temperatures reaching 10^32 degrees Celsius in the first few moments of the universe's existence. This unimaginable heat is responsible for the initial expansion and cooling of the universe.

**However, it's important to note that these temperatures are estimates and are constantly being refined as scientists develop new theoretical models and experimental techniques.**

**Ultimately, the hottest substance is not a fixed entity but rather a concept that is constantly evolving as our understanding of the universe expands. The search for the "hottest substance" is a quest to understand the fundamental nature of matter and energy at their most extreme limits.**

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Physicists using the Large Hadron Collider (LHC) at CERN, the European Centre for Nuclear Research, smashed heavy lead ions together at close to the speed of light. They generated temperatures of more than 1.6 trillion degrees Celsius, 100,000 times hotter than the centre of the Sun.read more >>