Temperature is the mark of average kinetic energy of the particles (in gases/liquid/solid/plasma ..)
At 0K, no more KE, so the negetive value of KE does not exist. You cannot make a temperature lower than 0K.
In space, there is almost no particles, so there is no temperature.
For the high temperature, in theory, you can make a unlimited high temperature, but in fact, at a very very high temperature, the high energy level would break down all the particles into basic particles (neutron and proton become quarks). And then it can become light (high energy photon).
In the early age of the universe, the temperature is very very high, scientists try to do experiment to make these high temperature, but still in process. Since these high temperature cannot make from your conventional method. Usually by particle accelerators to accelerate particle into a speed near light and hit at a target.
絕對零度,即絕對溫標的開始,是溫度的極限,相當於-273.15℃,當達到這一溫度時所有的原子和分子熱量運動都停止。這是一個只能逼近而不能到達的最底溫度。人類在1926年得到了0.71K 的低溫記錄,1957年創造了0.00002K的超低溫記錄,1989我國科學家創造了2X10 power -9 K的超低溫,目前,人們甚至已得到了距離絕對零度只差六億分之一的低溫,但仍不可能得到絕對零度。