The universe is expanding. How fast, exactly?

That is the question this site is about. It sounds simple. It is not. Two very careful ways of measuring the expansion of the universe give two different answers, and they do not agree. One says the universe expands at about 67 kilometers per second for every megaparsec of distance. The other says about 73. A megaparsec is a distance unit astronomers use — about 3.26 million light-years. So the two answers disagree by about 8 percent, and that is far too big to shrug off.

This disagreement has a name: the Hubble tension. It is one of the biggest open problems in all of science. If we cannot agree on how fast the universe is expanding, then we cannot be sure about how old the universe is, how big it is, or where it is headed.

What we are doing

We are building tensor maps of the universe's expansion from public telescope data, starting with the Roman Space Telescope and the James Webb Space Telescope. A tensor map is a map that does not just show where things are — it shows how the measurements themselves bend, drift, and shift when you look in different directions and at different distances.

Why map it that way? Because when two good measurements disagree, there are only a few shapes the disagreement can take. Maybe the answers cross somewhere in the middle. Maybe one answer slowly drifts away from the other the farther out you look. Or maybe the answer changes depending on which direction you look — like a bend in a road. Each shape points to a different kind of mistake, or a different kind of new physics. The tensor map tells us which shape we are actually looking at.

How we expect to achieve our goals

• Use the same public data everyone else uses. Roman and Webb data is public. We take the same sky, the same stars, the same galaxies — so the only thing that can differ is the measuring itself.
• Run everything on one honest measuring stick. Our tools are built for exactness: the same input must always give the same answer, on any computer. No rounding luck, no hidden settings.
• Check every direction, every distance, and both ways around. We run the maps forward and backward, from the middle outward, and from each end. If a result only shows up when you run it one way, it is not a real result.
• Show our work. When we have a number we trust, we will show how we got it, step by step, so anyone can check it.

Our goal is a single number we can defend: the true expansion rate of the universe, with the disagreement explained, not averaged away. Averaging two wrong numbers does not make a right one.

Where to start

What is a tensor? — the plain-language explanation: what a tensor is, what it does, and why we need the number it gives us.

Roman Tensors — what we will do with the Roman Space Telescope's giant sky surveys.

JWST Tensors — what we will do with the James Webb Space Telescope's sharp infrared eyes.

Space Telescopes — the fleet up there doing the work: their history, what they were built for, what they have proved, and links to their public sites. TESS gets its full credit here.

Weekly Updates — what's new, week by week.

This work is independent and unfunded. Nobody owns the answer, and nobody gets to shape it. The engine behind our tools is Accumath — a math engine built to give the right answer or an honest "I don't know," never a guess.