# Infinite time blow-up for the 3-dimensional energy critical heat equation

## TL;DR

This paper constructs solutions to the 3D energy-critical heat equation that blow up in infinite time with unbounded growth, confirming a conjecture and analyzing their stability and asymptotic behavior.

## Contribution

It provides the first explicit construction of infinite time blow-up solutions for the 3D energy-critical heat equation, verifying a conjecture by Fila and King.

## Key findings

- Solutions grow unboundedly as time approaches infinity.
- The growth rate depends on the initial data's decay rate.
- The solutions are co-dimension one stable.

## Abstract

We construct globally defined in time, unbounded positive solutions to the energy-critical heat equation in dimension three $$ u_t = \Delta u + u^5 , \quad {\mbox {in}} \quad \R^3 \times (0,\infty), \ \ u(x, 0)= u_0 (x)\inn \R^3. $$ For each $\gamma>1$ we find initial data (not necessarily radially symmetric) with $\lim\limits_{r \to \infty} |x|^\gamma u_0 (x) >0$ such that as $t \to \infty$ $$ \| u(\cdot ,t ) \|_\infty \sim t^{\gamma-1 \over 2} , \quad {\mbox {if}} \quad 1<\gamma <2, \quad \| u(\cdot ,t ) \|_\infty \sim \sqrt{t}, \quad {\mbox {if}} \quad \gamma >2, \quad $$ and $$ \| u(\cdot , t)\|_\infty \sim \sqrt{t}\, (\ln t )^{-1} , \quad {\mbox {if}} \quad \gamma = 2. $$ Furthermore we show that this infinite time blow-up is co-dimensional one stable. The existence of such solutions was conjectured by Fila and King.