Is There A Limit To How Hot An Object Can Get?

Yes. In our current physics, the absolute upper limit is the Planck temperature, about 1.4 × 10³² °C (or roughly the same number in kelvin) - the point at which gravity itself becomes a quantum effect and known physics breaks down. The hottest temperature humans have actually produced is around 5.5 trillion °C, made in 2012 at CERN’s Large Hadron Collider by smashing lead ions together.

It seems like we all miss the sun when it’s cold outside, even though we might hate it on hot summer days. Humans can only adapt to minor fluctuations in body temperature, which is why the weather is one of our favorite topics of conversation! During an average day of the year, our body temperature only changes by about 1 degree Celsius (roughly 2 degrees Fahrenheit) with the lowest temperature occurring during the night.

If the temperature is too high or too low, it can be lethal for warm-blooded species. If body temperature falls to 35°C or 95°F, it can result in hypothermia, while 40°C or 104°F leads to hyperthermia. However, most of us have nothing to worry about, since our surroundings rarely experience such broad temperature changes.

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Absolute Zero

Most people are pretty familiar with the concept of absolute zero, which is -273.15° C. It is also the lowest possible temperature that can be achieved, according to the laws of physics as we presently know them. This is because it’s the coldest that an entity can get when all of its heat energy has been sucked out of it. At this temperature (absolute zero), there is absolutely no motion, even at the subatomic level. Everything is frozen, even time. To put this in perspective, attempting to go below absolute zero would be like trying to get your car to go slower than completely stopped.

Other Celestial bodies:  A rather unimpressive white dwarf in the Red Spider Nebula shines at an estimated surface temperature of 150,000–250,000 °C, which is roughly 25 to 45 times hotter than the Sun’s surface and makes it one of the hottest known white dwarfs. Even hotter than that is a ‘quasar’, where a supermassive black hole at the centre radiates more energy than every star in the Milky Way put together. The inner accretion disk swirling into a quasar can reach tens of millions of degrees Celsius, hot enough to glow in X-rays.

Some of the most violent events in the universe are the deaths of giant stars. These events are called supernovas and emit huge bursts of energy in the form of gamma rays. If one of these occurred close enough to Earth, it could essentially wipe our world from existence; during the bounce that follows core collapse, temperatures in the heart of the supernova briefly soar to around 100 billion °C.

Subatomic Temperatures: Now, as we move up the temperature ladder, we need to come back to Earth. The hottest temperature humans have ever actually produced is at CERN’s Large Hadron Collider in Switzerland, where the ALICE experiment smashes lead ions together at almost the speed of light. For a split second, the resulting quark-gluon plasma reaches about 5.5 trillion °C, the current Guinness World Record, set in 2012. That is roughly 38% hotter than the earlier 4-trillion-degree benchmark set in 2010 with gold ions at Brookhaven National Laboratory’s Relativistic Heavy Ion Collider (RHIC) in New York. Either way, it is much higher than a supernova explosion or a nuclear explosion, and is high enough to melt even subatomic particles into a soupy mess.

Higher temperatures have never been recorded, although they can easily be theorized. First, we need to realize that every object with a higher temperature than Absolute Zero (-273.15°C) has a wavelength of emitted light associated with it. Even our bodies emit light, which lies in the infrared region of the spectrum and can only be seen through special cameras. As the temperature of an object rises, the wavelength of light associated with it decreases. The sun, being at a higher temperature than our bodies, can emit light with a much lower – and hence visible – wavelength.

Absolute Hot

In the standard cosmological model (Lambda-CDM, the modern Big Bang framework), the hottest possible temperature ever reached occurred a fraction of a second after the Big Bang. During that minuscule period of time, the emitted light only had a wavelength of 10^-35 meters. This length is called the Planck length and is the smallest measurable length in the Universe. Due to this small wavelength, the temperatures were as high as 10^32°C, which is called the Planck temperature and stands as the closest definition of an “absolute hot” that we currently have.

Beyond the Planck temperature being the hottest temperature ever theoretically reached in our universe, physicists hypothesize that at any temperature higher than the Planck standard, the gravitational forces of the affected particles would become so strong that they could create a black hole. A black hole that is created from energy, rather than matter, is called a ‘kugelblitz’ (German for ‘ball lightning’). A 2024 paper in Physical Review Letters argued that quantum effects like vacuum polarization may make a real kugelblitz impossible even though classical general relativity permits one, so a pure-light black hole may always remain a thought experiment. Either way, our currently accepted conventional models of physics break down past the Planck temperature, leaving many questions unanswered.

However, many scientists disagree with this model and believe that as we continue to learn about the subatomic behavior of matter, the maximum attainable temperature will continue to increase!