Remove extra space between equation and its serial number

I am working with the elsarticle document class in two-column format, but I have encountered a problem during the inclusion of equations in my document.

The issue is well described by the following MWE:

documentclass[3p,preprint]{elsarticle}

usepackage{multicol}
usepackage{amsmath,amssymb}
begin{document}

begin{multicols}{2}

begin{equation}
hspace*{-.4cm}
E_1=E_2=E_3=E_4=E_5=
begin{cases}
1, {rm~if~} 1=1, 
0, {rm~if~otherwise} 
end{cases}
end{equation}

end{multicols}

end{document}

I would like to move the equation to the left in order to lift the equation number to the previous line. If I use hspace*{-.3cm}, then nothing changes, while hspace*{-.4cm} moves the equation left, but creating large space between the equation and its serial number.

Is there any way that remove this extra space after the equation and before its serial number, thereby making the equation environment sensitive to the value of hspace*{}?

documentclass[3p,preprint]{elsarticle}

usepackage{multicol}
usepackage{amsmath,amssymb}
begin{document}

begin{multicols}{2}

aaadotfill aaa
begin{equation}
E_1=E_2=E_3=E_4=E_5=
begin{cases}
1, textrm{ if } 1=1, 
0, textrm{ if otherwise} 
end{cases}
hspace*{-.35cm}
end{equation}
bbbdotfill bbb

bbbdotfill bbb

bbbdotfill bbb

bbbdotfill bbb

bbbdotfill bbb

bbbdotfill bbb

bbbdotfill bbb

bbbdotfill bbb

end{multicols}

end{document}

documentclass[3p,preprint]{elsarticle}

usepackage{multicol}
usepackage{amsmath,amssymb}

usepackage{lipsum}

begin{document}

begin{multicols}{2}
lipsum*[1][1-2]
begin{equation}
hspace{0pt}
E_1=E_2=E_3=E_4=E_5=
begin{cases}
1, &text{if } 1=1, 
0, &text{if otherwise} 
end{cases}
hspace{1000pt minus 1fil}
end{equation}
lipsum[4-8]
end{multicols}

end{document}