What is the opposite of absolute zero?

Absolute hot

Terminal energy ???

This is the column being referred to by the OP I believe.

Say you accelerated a boson through empty space at within 10^-42 km/s of the speed of light. What would its temperature be?

Just for clarification: grumpy44134, you provided a link to a Wikipedia article that says nothing really different from what Cecil said?

A photon is a boson, and it’s already going at the speed of light.
You may be thinking of a fermion. Like an electron. Anyway, you’d get nowhere near that speed. Empty space is not actually empty. It’s full of radiation - the background radiation in the universe is very low, but the faster you travel at it, the more powerful it becomes, a lot like running at a brick wall. Or a better description. As you’re walking down the street, you don’t notice the air resistance - but if you’re on a motorbike travelling at high speeds you do. If you’re moterbike could travel faster than speed of sound, you’re be burned to a crisp very quickly.

I think of it as: there is no such thing as nothing. Space sort of is an ether after all, with it’s infinitesimal mass. I wonder though- if a portion of outer space were shielded from radiation, would that ‘empty space’ still have an effective mass?

Anyway, I was thinking of a Higgs boson. I don’t really know what it is though, or if temperature applies to it. And the whole question becomes perplexing, since space turns out to have mass and these particles don’t :confused:

One thing. There is no portion of space completely shield from radiation.

And the second thing. Empty space is never completely empty. Due to vacuum fluctuations, also called quantum fluctuations, there are always particles in empty space - they pop in an out of existence. So, in a cubic metre of empty space, there’s always roughly at least one hydrogen atom worth of mass.

Not many people know what a Higgs boson really is. The maths is too hard.
Temperature is not a thing in itself. It’s a measurement of something. It’s actually a measurement of two things that happen, and lead to the effect of either heat or coldness.

One thing is the movement of atoms and molecules - the faster they move, the hotter they seem to a thermometer or us - it’s actually their movement and when they bang off things like each other. They literally bang off each other like ping pong balls.

The second thing is radiation/light. Atoms banging off each other creates light (it’s one way light/radiation is created) Radiation/light can also nudge and push atoms around, causing them to go faster.

The atoms themselves are neither hot nor cold. They’re either moving fast or slowly. We experience the speed and force of these atoms as heat - or cold if they’re moving slowly.

We also experience sunlight as warmth - because when it hits the atoms on our skin it causes them to move.

That’s part of my problem though. If a portion of space could theoretically be isolated from background radiation, would it still have mass or not? I’m thinking of vacuum energy

I have a hard time with these ideas.

They sure are!

Ok, but the concept of ‘absolute hot’ in the OP considers black-hole formation to be the end of the road, since particles don’t really act like particles anymore in the way you describe at that point.

But what if that isn’t the limit? From the link above:

What if, in our quest for ‘absolute hot’, we went way, way past the point of black hole formation to an absurd conglomeration of massive black holes such that the result was the emission of virtual particles that exceeds the limits described by ‘absolute hot’? Is that even possible? What if the result were also bathed in a super-intense flood of Higgs bosons (which I assume are not affected by gravity?)- would that nudge the result up past the limit described in ‘absolute hot’?